Hydraulic fracturing fluids comprising micro proppant coke particles, methods of making same, and methods of hydraulic fracturing using same

Abstract

The fracturing fluid includes a carrier fluid and coke particles. The coke particles include micro-proppant coke particles (e.g., petroleum coke fines) having a particle size of at most 105 [mu] m wherein the micro-proppant coke particles have a total concentration of at least 3 wt% based on the total weight of the coke particles. The coke particles also have a total concentration in the fracturing fluid of 14 kg / m3 to 480 kg / m3, based on the volume of the carrying fluid. Methods include introducing such fracturing fluids into a subterranean formation.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of co - pending and co - assigned U.S. Patent Application No. 18 / 417,433, filed on January 19, 2024, entitled "HYDRAULIC FRACTURING FLUID COMPRISING MICROPROPPANT COKE PARTICLES, METHOD FOR MAKING SAME, AND HYDRAULIC FRACTURING PROCESSES USING SAME"; U.S. Patent Application No. 18 / 417,478, filed on January 19, 2024, entitled "METHODS FOR PERFORMING REFRACTURING OPERATIONS USING COKE PROPPANT PARTICLES"; U.S. Patent Application No. 18 / 417,492, filed on January 19, 2024, entitled "PROPPANT PARTICLES FORMED FROM FLUID COKE AND FLEXICOKE, FRACTURING FLUIDS COMPRISING SUCH PROPPANT PARTICLES, AND METHODS RELATED THERETO"; U.S. Patent Application No. 18 / 417,488, filed on January 19, 2024, entitled "HYDRAULIC FRACTURING METHODS UTILIZING COKE PROPPANT PARTICLES"; and U.S. Patent Application No. 18 / 417,483, filed on January 19, 2024, entitled "METHODS FOR PRODUCING HYDROCARBON FLUIDS WITH REDUCED WATER - OIL RATIO BY UTILIZING OIL - WET PETROLEUM COKE PROPPANT PARTICLES DURING HYDRAULIC FRACTURING", the contents of which are incorporated herein by reference in their entirety. Technical field

[0003] The present disclosure generally relates to the field of: hydraulic fracturing operations and proppant particles employed therein. More specifically, the present disclosure relates to the utilization of microproppant coke particles (such as those formed from petroleum coke fines during hydraulic fracturing operations). Background Art

[0004] This section is intended to introduce various aspects of the field that may be associated with embodiments of the present disclosure. Such a discussion is believed to be helpful in providing a framework for better understanding specific aspects of the present disclosure. Accordingly, it should be understood that this section should be read for this purpose and not necessarily as an acknowledgment of the prior art.

[0005] A wellbore can be drilled into a subterranean formation to facilitate the removal (or production) of materials such as hydrocarbons, coal, minerals, water, etc. In many cases, it is necessary to stimulate the subterranean formation in some way to facilitate the removal of resources. Stimulation can include any operation performed on the matrix of the subterranean formation to improve the fluid conductivity therethrough, including hydraulic fracturing, which is commonly used in unconventional reservoirs.

[0006] Hydraulic fracturing typically involves pumping a large volume of fracturing fluid into a subterranean formation (e.g., a low-permeability formation) at high hydraulic pressure to facilitate the formation of one or more fractures within the formation matrix and create highly conductive flow paths. Primary fractures extending from the wellbore are formed during the fracturing operation, and in some cases, secondary fractures extending from the primary fractures are formed. These fractures can be vertical, horizontal, or a combination of directions forming a tortuous path.

[0007] Proppant particles are typically included in the fracturing fluid. Once the fracturing fluid has been pumped into the subterranean formation, it is desirable that such proppant particles can be transported into the fractures and settle therein. Upon pressure release, the proppant particles retained in the fractures keep the fractures open by preventing fracture collapse, thereby facilitating the flow of desired products such as hydrocarbons from the fractured formation through the supported fractures into the wellbore. The performance of the proppant can significantly affect the recovery of expected products such as hydrocarbons.

[0008] Sand has traditionally been used as a proppant in hydraulic fracturing for the production of hydrocarbon products from unconventional wells. Various other types of proppants have been proposed and can be used to replace sand. Nevertheless, all of these existing proppants have one or more drawbacks, such as high cost and limited hydrocarbon recovery rates. Therefore, there is a real need in the industry for high-performance proppants, hydraulic fracturing fluids, and hydraulic fracturing methods. The present disclosure meets this need and others. Summary of the Invention Overview of the Invention

[0010] One aspect of the present disclosure provides a fracturing fluid comprising a carrier fluid and coke particles, wherein the coke particles comprise micro - proppant coke particles having a particle size of up to 105 micrometers (μm). The micro - proppant coke particles can have a total concentration of at least 3 weight percent (wt%), based on the total weight of the coke particles in the fracturing fluid. The coke particles can be present in the fracturing fluid at a concentration of from about 14 kilograms per cubic meter (120 pounds / 1000 gallons) to about 480 kilograms per cubic meter (4000 pounds / 1000 gallons), based on the volume of the carrier fluid.

[0011] Another aspect of the present disclosure provides a method of using such a fracturing fluid during a hydraulic fracturing operation. The method includes introducing the fracturing fluid into a subterranean formation and depositing at least a portion of the micro - proppant coke particles within secondary fractures in the subterranean formation. The micro - proppant coke particles can have a total concentration of at least 3 weight percent (wt%), based on the total weight of the coke particles in the fracturing fluid. The coke particles can be present in the fracturing fluid at a concentration of from about 14 kilograms per cubic meter (120 pounds / 1000 gallons) to about 480 kilograms per cubic meter (4000 pounds / 1000 gallons), based on the volume of the carrier fluid.

[0012] Another aspect of the present disclosure provides a method of preparing a fracturing fluid. The method includes providing a first collection of coke particles comprising micro - proppant coke particles, wherein the micro - proppant coke particles have a particle size of up to 105 μm. The method can include mixing the first collection of coke particles with at least a carrier fluid and optionally a second collection of proppant particles, wherein the total concentration of the micro - proppant coke particles is at least 3 wt%, based on the total weight of the coke particles included in the first collection of coke particles and the second collection of proppant particles. The coke particles are mixed with the carrier fluid in an amount of from about 14 kilograms of coke particles per cubic meter (120 pounds / 1000 gallons) of carrier fluid to about 480 kilograms of coke particles per cubic meter (4000 pounds / 1000 gallons) of carrier fluid.

[0013] These and other features and attributes of the disclosed aspects and embodiments of the present disclosure, as well as their advantageous applications and / or uses, will be apparent from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] To assist one of ordinary skill in the relevant art in making and using the subject matter described herein, reference is made to the accompanying drawings, in which:

[0015] Figure 1 is a diagram showing the typical size ranges of primary and secondary fractures compared to the particle size distributions of micro - proppants and standard - sized non - coke proppants;

[0016] Figure 2 is a diagram comparing the propped area of exemplary fractures using different types and combinations of proppants and microproppants; and

[0017] Figure 3 is a diagram showing the typical particle size distribution of fine flexicoke produced via the FLEXICOKING TM process;

[0018] Figure 4 is a process flow diagram of an exemplary method of using the fracturing fluid described herein during a hydraulic fracturing operation; and

[0019] Figure 5 is a process flow diagram of an exemplary method of preparing the fracturing fluid described herein.

[0020] It should be noted that the figures are merely examples of the present disclosure and are not intended to limit the scope of the present disclosure. Additionally, the figures are generally not drawn to scale and are drawn for convenience and clarity to illustrate aspects and embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0022] In the following detailed description section, specific examples of the present disclosure are described in connection with preferred aspects and embodiments. However, to the extent that the following description is specific to one or more aspects or embodiments of the present disclosure, this is intended for exemplary purposes only and simply provides an illustration of these aspects or embodiments. Accordingly, the present disclosure is not limited to the specific aspects and embodiments described below, but includes all alternatives, improvements, and equivalents falling within the true spirit and scope of the appended claims.

[0023] First, for ease of reference, certain terms used in this application and their meanings as used in the context are set forth. In cases where a term used herein is not defined below, the broadest definition that would be given to that term by one of ordinary skill in the art, as reflected in at least one printed publication or issued patent, shall be given. Additionally, the present disclosure is not limited by the use of the terms shown below, as all equivalents, synonyms, new developments, and terms or processes serving the same or similar purposes are considered to be within the scope of the present claims.

[0024] As used herein, when applied to any embodiment described herein, the singular forms "a", "an", and "the" mean one or more. The use of "a", "an", and / or "the" does not limit the meaning to a single feature unless such a limitation is specifically stated.

[0025] The terms "about" and "approximately" mean the relative amounts of materials or properties sufficient to provide the desired effect. The degree of exact deviation permitted in some cases may depend on the specific context, such as ±1%, ±5%, ±10%, ±15%, etc. Those skilled in the art should understand that these terms are intended to allow the description and claim of certain features without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that non-substantive or immaterial modifications or variations of the described subject matter are considered to be within the scope of the present disclosure.

[0026] The term "and / or" placed between a first entity and a second entity means (1) the first entity, (2) the second entity, and (3) one of the first entity and the second entity. Multiple entities listed with "and / or" shall be interpreted in the same manner, i.e., "one or more" of the entities so combined. Other entities may optionally exist in addition to the entities specifically identified by the "and / or" clause, whether related or unrelated to those specifically identified. Thus, as a non-limiting example, when used in conjunction with open-ended language such as "comprising", a reference to "A and / or B" may, in one embodiment, refer only to A (optionally including entities other than B); in another embodiment, only to B (optionally including entities other than A); in yet another embodiment, to both A and B (optionally including other entities). These entities may refer to elements, actions, structures, steps, operations, values, etc.

[0027] The term "any" as used herein means one, some, or all of the designated entity or group of entities, regardless of quantity.

[0028] The term "apparent density" as used herein with respect to the density of proppant particles means the density of an individual particle itself, which may be expressed in grams per cubic centimeter (g / cm 3 ). The apparent density values provided herein are based on the American Petroleum Institute's Recommended Practice 19C (hereinafter referred to as "API RP-19C") standard, entitled "Measurement of Properties of Proppants Used in Hydraulic Fracturing and Gravel-packing Operations" (First Edition May 2008, Reaffirmed June 2016).

[0029] When used in reference to a list of one or more entities (or elements), the phrase "at least one" shall be understood to mean at least one entity selected from any one or more of the entities in the list of entities, but not necessarily including at least one of each of the specifically listed entities within the list of entities, and not excluding any combinations of entities in the list of entities. This definition also allows entities other than those specifically identified within the list of entities referred to by the phrase "at least one" to optionally exist, whether related or unrelated to those specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B", or equivalently, "at least one of A and / or B") can, in one embodiment, refer to at least one A, optionally including more than one A, with no B present (and optionally including entities other than B); in another embodiment, to at least one B, optionally including more than one B, with no A present (and optionally including entities other than A); and in yet another embodiment, to at least one (optionally including more than one) A and at least one (optionally including more than one) B (and optionally including other entities). In other words, the phrases "at least one", "one or more", and "and / or" are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions "at least one of A, B, and C", "at least one of A, B, or C", "one or more of A, B, and C", "one or more of A, B, or C", and "A, B, and / or C" can represent A alone, B alone, C alone, A and B together, A and C together, B and C together, A, B, and C together, and optionally any one of the foregoing in combination with at least one other entity.

[0030] As used herein, the term "blast furnace coke" refers to any coal-derived coke suitable for use in a blast furnace for making steel.

[0031] The term "delayed coke" as used herein refers to a solid, concentrated carbonaceous material produced in a delayed coking unit by the delayed coking process. According to the delayed coking process, a preheated feedstock is introduced into a fractionator where it undergoes a thermal cracking process in which long-chain hydrocarbons are split into shorter-chain hydrocarbons. The resulting lighter fractions are then removed as side stream products. The fractionator bottoms, which include the recycle stream containing the heavy product, are heated in a furnace that can have an outlet temperature, for example, of about 895°F to about 960°F. Exemplary outlet temperature ranges include about 900°F to about 910°F, about 910°F to about 920°F, about 920°F to about 930°F, about 930°F to about 940°F, about 940°F to about 950°F, and about 950°F to about 960°F, to name just a few non-limiting examples. The heated feedstock then enters a reactor, referred to as a "coke drum", which can operate at a temperature, for example, of about 780°F to about 840°F. Exemplary ranges of reactor temperature include about 780°F to about 790°F, about 790°F to about 800°F, about 800°F to about 810°F, about 810°F to about 820°F, about 820°F to about 830°F, and about 830°F to about 840°F, to name just a few non-limiting examples. Inside the coke drum, the cracking reaction continues. The resulting cracked products then leave the coke drum as an overhead stream while coke deposits in the coke drum. Typically, this process continues for a time period of about 16 hours to about 24 hours to allow the coke drum to fill with coke. Exemplary ranges of the specific cracking process time include about 16 hours to about 18 hours, about 18 hours to about 20 hours, about 20 hours to about 22 hours, and about 22 hours to about 24 hours, to name a few non-limiting examples. In addition, to allow the delayed coking unit to operate on an intermittent continuous (or semi-continuous) basis, two or more coke drums are used. While one coke drum is being filled with coke online, the other coke drum can be steam stripped, cooled, decoked (e.g., via hydraulic cutting of the deposited coke with water), pressure checked, and heated up. In addition, the overhead stream leaving the coke drum enters a fractionator where naphtha and heating oil fractions are recovered. The heavy recycle material is then typically combined with the preheated fresh feedstock and recycled back into the process.

[0032] When used in reference to one or more components, features, structures, or methods in accordance with the present disclosure, the terms "instance", "exemplary", and "embodiment" as used herein are intended to convey that the described component, feature, structure, or method is an illustrative, non-exclusive instance of a component, feature, structure, or method in accordance with the present disclosure. Accordingly, the described component, feature, structure, or method is not intended to be restrictive, mandatory, or exclusive / exhaustive; and other components, features, structures, or methods, including those that are structurally and / or functionally similar and / or equivalent, are also within the scope of the present disclosure.

[0033] The term "flexicoke" as used herein refers to TM Solid concentrated carbon material produced by the process, FLEXICOKING TM The FLEXICOKING process is a thermal cracking process that utilizes fluidized solids and gasification to convert heavy, low-grade hydrocarbon feedstocks into light hydrocarbon products (e.g., upgraded, more valuable hydrocarbons). TM The process integrates the cracking reactor, heater and gasifier into a common fluidized solid (coke) circulation system. The feed stream (of the residue) is fed into the fluidized bed together with the stream of the hot recycle material to the reactor. The stream containing coke is circulated from the reactor to the heating vessel, where it is heated. The hot coke stream is sent from the heater to the gasifier, where it reacts with air and steam. The gasifier product gas (called coke gas) containing entrained coke particles is returned to the heater and cooled by the cold coke from the reactor to provide a part of the reactor heat demand, which is generally in the range of about 496°C to about 538°C. Exemplary ranges of reactor heat that can be used include about 496°C to about 500°C, about 500°C to about 510°C, about 510°C to about 520°C, about 520°C to about 530°C, about 530°C to about 538°C, just to name a few non-limiting examples. The coke return stream sent from the gasifier to the heater provides the remaining heat demand. The coke that satisfies the heat demand is then circulated to the reactor, and the feed stream is thermally cracked to produce light hydrocarbon liquids, which are removed from the reactor and recovered using conventional fractionation equipment. Fluid coke is formed by the thermal cracking process and settles (deposits) onto the "seed" fluidized bed coke already present in the reactor. The resulting at least partially vaporized coke is flexible coke. In some cases, the coke from the thermal cracking process is deposited on top of the surface of the seed coke in a pattern that appears to be ring-like. In normal FLEXICOKING TM Flexicoke is continuously removed from the system during processing (e.g., from the reactor or after it is passed to the heater via the elutriator) to ensure that the system maintains the coke particles within the fluidizable particle size range. TM A readily available by-product of the process.

[0034] Relatedly, the terms "wet flexicoke fines" and "dry flexicoke fines" refer to FLEXICOKING TM Two by-products of the process. Such by-products are collected as particles that are not recovered in the secondary cyclone separator of the heater. More specifically, the particles are first collected in the tertiary cyclone separator as dry flexible coke fines, and then the smaller particles that pass through the tertiary cyclone separator are recovered in the venturi scrubber as wet flexible coke fines.

[0035] As used herein, the term "fluid coke" refers to the solid, concentrated carbonaceous material remaining from fluid coking. The term "fluid coking" refers to a thermal cracking process that uses fluidized solids to convert heavy, low-grade hydrocarbon feeds into lighter products (e.g., upgraded hydrocarbons), producing fluid coke as a by-product. The fluid coking process differs from the FLEXICOKING TM process in that the fluid coking process does not include a gasifier.

[0036] The term "fracture" (or "hydraulic fracture") refers to a broken crack or fracture surface within a subterranean formation, which can be natural or caused by applied pressure or stress. "Primary fracture" means a fracture or any section of a fracture having a size capable of allowing a rigid sphere with a diameter of 1 millimeter (mm) to pass through. "Secondary fracture" refers to a fracture or any section of a fracture that is not a primary fracture.

[0037] As used herein, the term "metallurgical coke" refers to a class of coal-derived coke produced by heating coal, which causes the fixed carbon to fuse into the inherent ash and drives off a large percentage of the volatile matter. The resulting metallurgical coke particles include a range of different sizes, with the smallest particles being fine powder (sometimes referred to as "coke breeze").

[0038] When used herein with reference to a type of particle, the term "particle size (one or more)" refers to the diameter (one or more) of such particle(s). When used herein with reference to a type or collection of particles, the term "particle size distribution" refers to the range of diameters of such particles, typically from smallest to largest. When used herein with reference to a type or collection of particles, the terms "average particle size distribution" and "D50" are interchangeably used to refer to the median particle size of the particles.

[0039] The term "petroleum coke" refers to the final carbon-rich solid material derived from oil refining. More specifically, petroleum coke is the carbonization product of high-boiling hydrocarbon fractions obtained as a result of petroleum processing operations. Petroleum coke is produced via a thermal cracking process within a coking unit, where long-chain hydrocarbons are split into shorter-chain hydrocarbons. As described herein, there are at least three main types of petroleum coke: delayed coke, fluid coke, and flexicoke. Each type of petroleum coke is produced using a different coking process; however, the common goal of all three coking processes is to maximize the yield of distillate products within a refinery by removing a large amount of carbon in the form of coke from the resid.

[0040] The term "coal-derived coke" refers to any coke prepared from coal, for example, by heat treatment.

[0041] As used herein with reference to the settling or deposition of a particular type of proppant in one or more particular regions of a subterranean formation, the term "preferably" refers to the tendency of the proppant to settle or deposit in such region(s), but does not mean that the proppant will settle or deposit only in such region(s). In operation, it is expected that a certain amount of proppant will settle or deposit in various regions of the subterranean formation. However, the characteristics of the proppant may make it more likely to settle or deposit in a particular region(s) compared to other types of proppants.

[0042] As used herein, the terms "proppant" and "proppant particle" refer to solid materials capable of keeping induced fractures open during and after a hydraulic fracturing treatment. The term "proppant pack" refers to an assembly of proppant particles.

[0043] The terms "coke proppant" and "coke proppant particle" refer to a proppant based on or derived from a solid carbonaceous material produced by treating a carbonaceous material (e.g., oil (e.g., crude oil, vacuum pipe stills, etc.), coal, and hydrocarbons) at high temperature in an oxygen-deficient environment. The high temperature can be at least 200, 250, 300, 350; 400, 450, 500, 600, 700, 800, 900 or even 1000 °C. The carbonaceous material contains carbon element and optionally additional elements including but not limited to hydrogen, sulfur, vanadium, iron, etc. Based on the total weight of all elements in the carbonaceous material, the carbonaceous material preferably contains carbon element at a concentration of ≥ 50 wt%, e.g., 50, 55, 60, 65, 70 wt% to 75, 80, 85, 90, 95 wt% to 96, 97, 98, 99 wt% or even 100 wt%. Based on the total weight of all elements in the carbonaceous material, the carbonaceous material preferably contains carbon element and hydrogen element at a total concentration of ≥ 55 wt%, e.g., 55, 60, 65, 70 wt% to 75, 80, 85, 90, 95 wt% to 96, 97, 98, 99 wt% or even 100 wt%.

[0044] The term "non-coke proppant" refers to any proppant that does not contain coke proppant particles. Examples of non-coke proppants include sand, ceramic proppants, glass proppants, and polymer proppants.

[0045] The term "lightweight proppant (LWP)" refers to a proppant having an apparent density in the range of about 1.2 g / cm 3 to about 2.2 g / cm 3 (e.g., about 1.2, 1.3, 1.4, 1.5, 1.6 g / cm 3 to about 1.7, 1.8, 1.9, 2.0, 2.1, 2.2 g / cm 3 ), and the term "ultra-lightweight proppant (ULWP)" refers to a proppant having an apparent density in the range of about 0.5 g / cm3 to about 1.2 g / cm 3 in the range (e.g., about 0.5, 0.6, 0.7, 0.8 g / cm 3 to about 0.9, 1.0, 1.1, 1.2 g / cm 3 ). The proppant can be or can not be LWP. The term "non-LWP proppant" refers to a proppant having an apparent density higher than 2.2 g / cm 3 (e.g., about 2.3, 2.4, 2.5 to about 2.6, 2.8, 3.0 to 3.2, 3.4, 3.5 g / cm 3 ). The non-coke proppant can be or can not be non-LWP.

[0046] The term "micro-proppant coke particles" refers to a collection of coke proppant particles having a particle size of at most 105 μm, but possibly in the range of about 0.0001 μm to 105 μm (e.g., about 0.0001, 0.001, 0.01, 0.1 μm to 0.5, 1.0, 2.0, 5.0, 8.0, 10 μm to 15, 20, 25, 30, 35, 40, 45 μm to 50, 53, 55, 60, 63, 65 μm to 74, 75, 80, 85, 88, 90, 95, 100, 105 μm). The term "petroleum coke fines" refers to a collection of micro-proppant coke particles derived from petroleum source materials.

[0047] As used herein, the term "pyrolysis coke" refers to a type of coke produced via hydrocarbon pyrolysis at a temperature higher than the coking process used to prepare petroleum coke.

[0048] When referring to the amount or quantity of a material or its specific properties, the term "substantially" means an amount sufficient to provide the effect that the material or property is intended to provide. In some cases, the allowable degree of exact deviation may depend on the specific range.

[0049] When referring to the components of a composition, the terms "substantially free of" or "essentially free of" are used interchangeably to mean that the composition contains the component at a concentration of ≤10 wt%, ≤5 wt%, ≤3 wt%, ≤1 wt% or 0 wt%, based on the total weight of the composition, depending on the details of the particular embodiment.

[0050] As used herein, the term "thermally post-treated coke" refers to petroleum coke that has been heated to a temperature in the range of about 400°C to about 1200°C for a predetermined duration in the range of about 1 minute to about 24 hours. Exemplary temperature ranges for heating the thermally post-treated coke include about 400°C to about 500°C, about 500°C to about 600°C, about 600°C to about 700°C, about 700°C to about 800°C, about 800°C to about 900°C, about 900°C to about 1000°C, about 1000°C to about 1100°C, and about 1100°C to about 1200°C, to name just a few non-limiting examples. Exemplary time ranges for heating the thermally post-treated coke include about 1 minute to about 1 hour, about 1 hour to about 2 hours, about 2 hours to about 4 hours, about 4 hours to about 8 hours, about 8 hours to about 12 hours, about 12 hours to about 16 hours, about 16 hours to about 20 hours, and about 20 hours to about 24 hours, to name just a few non-limiting examples.

[0051] The term "wellbore" refers to a borehole drilled into a subterranean formation. The borehole can include vertical, deviated, highly deviated, and / or horizontal sections. The term "wellbore" also includes downhole equipment associated with the borehole, such as casing strings, production tubing, gas lift valves, and other subterranean equipment. Correlatively, the term "hydrocarbon well" (or simply "well") includes the wellbore in addition to the wellhead and other associated surface equipment.

[0052] Certain embodiments and features are described herein using a set of numerical upper limits and a set of numerical lower limits. It is understood that ranges from any lower limit to any upper limit are to be considered, unless otherwise stated. All numerical values are "about" or "approximately" indicated values, and experimental errors and deviations that would be expected by a person of ordinary skill in the art are taken into account.

[0053] Turning now to the details of the present disclosure, microproppants can be effectively utilized during hydrocarbon fracturing operations, resulting in increased production from the corresponding hydrocarbon wells. Specifically, while standard-sized non-coke proppants typically settle within the larger native fractures of the subterranean formation, microproppants are particularly suited to travel into the smaller secondary fractures. This is at least in part due to the smaller particle size of the microproppants. This is illustrated by Figure 1 Illustrated, Figure 1 is Diagram 100 showing the typical size ranges of native and secondary fractures compared to the particle size distributions of microproppants and standard-sized non-coke proppants. Specifically, as Figure 1As shown, the size of the fracture pores of secondary fractures is typically in the range of less than 10 micrometers (μm) to greater than 100 μm, while the particle size of non-coke proppants of standard size is typically greater than 100 μm. This generally prevents non-coke proppants of standard size from being transported into secondary fractures with smaller fracture pores. This is at least partly due to the fact that the fracture pores must be larger than the proppant size to prevent bridging effects. For example, laboratory-scale experiments have shown that natural fractures (or secondary fractures) with fracture pores of 450 μm will not allow proppants with a particle size exceeding 64 μm to pass through. A review of this laboratory-scale study is provided in Table 1, which compares the size of the fracture pores with the maximum proppant sizes that will respectively prevent bridging (or plugging) and allow particles to pass through. In other words, referring to Table 1, for fracture pores of 450 μm, a proppant size of at most 149 μm (or 100 mesh) is unlikely to cause bridging effects, while a proppant size of at most 64 μm (or 230 mesh) is likely to pass through the fracture pores.

[0054] Based on Table 1, it is evident that micro-proppants are more suitable for supporting secondary fractures compared to non-coke proppants of standard size. As a result, micro-proppants can be used to effectively expand the stimulated reservoir volume (SRV) by increasing the total supported area in the subterranean formation.

[0055] Table 1

[0056]

[0057] In addition, compared to non-coke proppants, micro-proppants exhibit enhanced transport properties. Specifically, based on Stokes' law, the settling rate of proppant particles (i.e., the settling velocity, denoted as vt) is a function of the density of the carrier fluid (ρ f ), the density of the proppant particles (ρ p ), and the particle size / diameter of the proppant particles (D p ), as given by Equation 1:

[0058]

[0059] where g is the gravitational constant and μ f is the viscosity of the carrier fluid. In addition, the particle size has a significant impact factor as it is a squared function. A reduced particle size can result in a greater reduction in the settling velocity, thus causing the proppant particles to be further carried into the primary and secondary fractures.

[0060] A hydraulic fracturing operation for a given stage generally includes two phases: a pad phase and a slurry phase following the pad phase. In the pad phase, a high-pressure fracturing fluid that generally does not contain proppant, or, in rare cases where non-coke microproppant is used, a high-pressure fracturing fluid containing a relatively small loading of non-coke microproppant, is injected through a wellbore into a formation to break the formation and create a "pad" containing some initial fractures. During the slurry phase, a high-pressure proppant-containing fracturing fluid is additionally injected into the pad and the initial fractures created in the pad phase, thereby creating more fractures and distributing proppant particles within the fractures. Typical hydraulic fracturing applications of currently available non-coke microproppants include injecting about 5,000 to about 15,000 pounds of microproppant per stage only during the pad phase. The theory behind this pumping strategy is to allow the microproppant to be pumped before the non-coke proppant so that the microproppant coke particles settle within secondary fractures before the smaller fracture pores are blocked by the settlement of the non-coke proppant within the corresponding primary fracture(s).

[0061] In addition, the use of microproppants can advantageously reduce pressure-dependent leakage of the fracturing fluid into the surrounding formation. This, in turn, can enable lower treating pressures, higher pumping rates, and reduced pumping time for the overall treatment. Further, while it is not uncommon for high pressures within the formation to limit the total pumped proppant volume to about 20% or less of the designed amount, the use of microproppants can enable the designed proppant volume to be fully pumped into a difficult-to-treat formation, thereby further enhancing the effectiveness of the hydraulic fracturing operation.

[0062] However, despite the benefits of using microproppants in hydraulic fracturing operations, the relatively high cost of currently available microproppants has imposed a practical limit on the volume of microproppants used per hydrocarbon well. In particular, as noted above, non-coke microproppant injection involving commercially available microproppants that do not contain coke particles is generally limited to about 5,000 to about 15,000 pounds of microproppant per stage only during the pad phase, where it is generally cost-prohibitive to explore injecting those microproppants during the remainder of the overall treatment (i.e., after the pad phase is completed). However, with this injection of microproppants only during the pad phase, there is no practical expectation that the microproppant coke particles will travel deeply into the subterranean formation because the first 600 to 1,000 barrels (95.4 to 159.0 cubic meters) of fracturing fluid injected during the pad phase generally do not reach the fracture tips. As a result, according to the current strategy using currently available non-coke microproppants, the microproppant coke particles only support the first few hundred feet (at most) of the first half of the length of the fracture.

[0063] The present disclosure alleviates the aforementioned difficulties and also provides related advantages. In particular, the present disclosure provides micro - proppant coke particles formed from (e.g., comprising, consisting essentially of, or consisting of) petroleum coke fines and / or other coke materials having a particle size of up to 105 μm. Such micro - proppant coke particles are provided in a fracturing fluid at a concentration of at least 3 wt% (e.g., 3, 4, 5, 6, 7, 8, 9, 10 wt% up to 15, 20, 25, 30, 35, 40, 45, 50 wt% up to 55, 60, 65, 70, 75, 80, 85 wt% up to 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100 wt%), where the weight percentage of the particles can be determined prior to mixing the particles with the carrier fluid (e.g., based on the dry particles). The coke particles are desirably dispersed in the carrier fluid. Additionally, such a fracturing fluid can be introduced into a subterranean formation during a hydraulic fracturing operation in a horizontal, vertical, or deviated wellbore (including hydrocarbon - producing wellbores and / or water - producing wellbores). Introducing such micro - proppant coke particles into the subterranean formation can effectively support the extended regions of the primary and secondary fractures in the subterranean formation.

[0064] In addition to the micro - proppant coke particles, the fracturing fluid of the present disclosure may further comprise a second portion of coke particles having a size greater than 105 μm. Generally, the total concentration of coke particles in the fracturing fluid is at least 14 kilograms (kg) of coke particles per cubic meter (m 3 ) of carrier fluid, and can be, for example, in the range of 14, 15, 16, 17, 18, 19, 20 kg·m -3 up to 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 kg·m -3 up to 35, 40, 45, 50, 55, 60, 65, 70 kg·m -3 up to 80, 90, 95, 96, 100, 150, 160, 180, 200 kg·m -3 up to 220, 240, 250, 260, 280, 300 kg·m -3 up to 350, 400, 450, 480 kg·m -3 of the carrier fluid volume. A concentration range of 18 to 120 kg·m -3 is highly desirable. A preferred concentration range is 23 to 96 kg·m -3 . The total coke particle concentration in the fracturing fluid is less than 14 kg·m -3When introducing the amount of coke particles into the subterranean formation is too low to serve as an effective proppant under a given reasonable volume of carrier fluid; or, if a reasonable amount of coke particles is introduced into the subterranean formation, it may be necessary to inject an infeasibly large volume of carrier fluid. Either situation may be highly undesirable. When the concentration of coke particles in the fracturing fluid is higher than 480 kg·m -3 , the cost of the coke particles may be too high to justify a higher amount of additional benefits (if any).

[0065] Thus, in the fracturing fluid of the present disclosure, when all of the coke particles present are microproppant coke particles, the weight concentration of the microproppant coke particles relative to the volume of the carrier fluid therein can be, for example, from 14 to 480 kg·m -3 , preferably from 18 to 120 kg·m -3 , more preferably from 23 to 96 kg·m -3 . When the concentration of the microproppant coke particles is x weight percent of the total weight of all of the coke particles present in the fracturing fluid, the concentration of the microproppant coke particles by weight relative to the volume of the carrier fluid therein can be, for example, from 14*x% to 480*x% kg·m -3 , preferably from 18*x% to 120*x% kg·m -3 , more preferably from 23*x% to 96*x% kg·m -3 .

[0066] While not wishing to be bound by a particular theory, it is believed that in many modern unconventional hydrocarbon recovery methods involving horizontal drilling and hydraulic fracturing, hydrocarbon-bearing subterranean formations tend to have very low permeability such that fluid loss due to the presence of natural fractures is not a significant problem. Thus, the coke particles in the fracturing fluid of the present disclosure serve substantially as a proppant rather than a fluid loss control agent by keeping the induced fractures open ("propped") after pressure release following hydraulic fracturing, thereby allowing hydrocarbons to migrate from the formation through the induced fractures to the wellbore during hydrocarbon production. Generally and regardless of particle size, the coke particles tend to remain dispersed in the carrier fluid for a longer time rather than settle out due to their low apparent density, enabling them to be transported further to remote fracture locations than heavy proppant particles (such as sand and commercially available microproppant particles based on ceramic materials) to keep more and longer fractures open, thereby enhancing hydrocarbon recovery. Additionally, the microproppant coke particles can remain in the carrier fluid even longer than coke particles larger than 105 μm due to their small size, enter fractures even further from the wellbore and fractures smaller than 105 μm near or far from the wellbore, keep those fractures open, and significantly improve hydrocarbon recovery during production.

[0067] In some embodiments (pad-phase only embodiments), the fracturing fluid comprising microproppant coke particles is injected into the subterranean formation only during the pad phase of a hydraulic fracturing operation, before injecting another fracturing fluid comprising one or more other types of proppant particles such as non-coke proppants (e.g., sand), LWP, and / or ULWP. In some embodiments, during the pad phase, the fracturing fluid does not contain other proppant particles in addition to the microproppant coke particles. In some embodiments, during the pad phase, in addition to the microproppant coke particles, the fracturing fluid may further contain other microproppant particles, such as: glass microproppants, ceramic microproppants, polymer microproppants, sand microproppants, and combinations thereof. In such embodiments, based on the total weight of all microproppant particles in the fracturing fluid, the microproppant coke particles may be present at a concentration of, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt% to 60 wt%, 70 wt%, 80 wt%, 90 wt%, 95 wt%, 98 wt%. While not wishing to be bound by a particular theory, it is believed that due to the low density and small size of the microproppant coke particles, they can be conveniently transported into a majority (e.g., ≥50%, ≥60%, ≥70%, ≥80%, ≥90%, ≥95%) of the initial fractures created during the pad phase, more so than commercially available microproppants based on ceramic materials. Subsequently, during the slurry phase, the microproppant coke particles already present in the initial fractures can be further transported into the additional fractures created during the slurry phase, particularly secondary fractures, and remain supported after the pressure is reduced, enabling greater production of hydrocarbon products via the more supported fractures during the production phase of the well. Thus, by including microproppant coke particles in the fracturing fluid during the pad phase, it may become unnecessary to further include microproppant particles in the fracturing fluid during the subsequent slurry phase. During the pad phase, while non-microproppant proppant particles, such as coke particles larger than 105 μm in size, may be included, preferably, ≥50 wt%, ≥60 wt%, ≥75 wt%, ≥80 wt%, ≥90 wt%, ≥95 wt% or even 100 wt% of the proppant particles present in the fracturing fluid are microproppant particles, based on the total weight of the proppant particles present in the fracturing fluid. Large-sized proppant particles (e.g., those larger than 105 μm in size) if used in large quantities may cause some of the initial fractures created during the pad phase to be screened out, thereby reducing the effectiveness of the fracturing operation during the pad phase and the subsequent slurry phase.

[0068] In some other embodiments (slurry-phase only embodiments), the fracturing fluid containing microproppant coke particles is injected into the subterranean formation only in the slurry phase and not in the pad phase. In such slurry-phase only embodiments, the fracturing fluid used during the pad phase may contain no proppant or may contain non-coke microproppant particles. In some such embodiments, during the slurry phase, the fracturing fluid does not contain other proppant particles in addition to the microproppant coke particles. In some embodiments, during the slurry phase, in addition to the microproppant coke particles, the fracturing fluid may further contain other proppant particles, such as: non-coke microproppant particles; coke proppant particles having a size greater than 105 μm; non-coke proppant particles having a size greater than 105 μm; and combinations thereof. In such embodiments, based on the total weight of all coke particles in the fracturing fluid, the microproppant coke particles may be present at a concentration of, for example, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt% to 20 wt%, 30 wt%, 40 wt%, 50 wt% to 60 wt%, 70 wt%, 80 wt%, 90 wt%, 95 wt%, 98 wt%, 100 wt%. In such embodiments, based on the total weight of all proppant particles in the fracturing fluid, the microproppant proppant particles may be present at a concentration of, for example, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt% to 20 wt%, 30 wt%, 40 wt%, 50 wt% to 60 wt%, 70 wt%, 80 wt%, 90 wt%, 95 wt%, 98 wt%, 100 wt%. When the fracturing fluid contains both microproppant coke particles and other types of proppant particles, the microproppant coke particles can be transported with the other types of proppant particles into the primary fractures and settle there in various amounts. However, the properties of the microproppant coke particles (e.g., low density and small size) enable at least a portion of such microproppant coke particles to self-separate from other type(s) of proppant particles in the subterranean formation, such that the other type(s) of proppant particles can preferentially settle within the primary fracture(s), while the microproppant coke particles further travel into the formation and preferentially settle within the secondary fractures. In this way, the microproppant coke particles described herein are used to increase the stimulated reservoir volume (SRV) of the corresponding formation by supporting an extended fracture region that cannot be achieved using other types of proppant particles such as coke particles having a size greater than 105 μm, sand, and commercially available microproppant particles based on ceramic materials.

[0069] In still other embodiments (two-stage embodiments), the fracturing fluid comprising microproppant coke particles can be injected into the subterranean formation during the pad phase in substantially the same manner as described above in connection with the only pad phase embodiment, and during the slurry phase in substantially the same manner as described above in connection with the only slurry phase embodiment. The use of microproppant coke particles in the fracturing fluid during the pad and slurry phases can enable more microproppant coke particles to be transported into more secondary fractures and fractures at greater distances from the wellbore.

[0070] Figure 2 is a diagram 200 comparing the supported areas of exemplary fractures using different types and combinations of proppants and microproppants. Specifically, as Figure 2 shown, when a fracturing fluid containing only sand as a proppant is injected into a fracture, due at least in part to the relatively large particle size and high density of the sand particles, the sand particles rapidly settle in the near-wellbore region of the fracture. When a fracturing fluid containing a combination of sand and currently available non-coke microproppants is injected into a fracture, due to the relatively small particle size of the non-coke microproppant particles, the microproppant particles travel further into the fracture than the sand. However, it is noted that when a fracturing fluid containing a combination of sand and the microproppant coke particles described herein is injected into a fracture, the microproppant coke particles, having a smaller particle size and a significantly lower density, can be transported much further than currently available non-coke microproppants within the fracture and settle at least in part in out-of-the-way areas of the primary and secondary fractures, beyond the reach of currently available non-coke microproppants. Thus, compared to injecting a fracturing fluid containing commercially available microproppants, a greater total supported area can be achieved by injecting a fracturing fluid containing the microproppant coke particles described herein, resulting in an increase in the stimulated reservoir volume ("SRV") of the well.

[0071] According to the embodiments described herein, the microproppant coke particles can comprise (e.g., consist of, consist essentially of, or consist of) as FLEXICOKING TMWet and / or dry flexicoke fines produced as by-products of the process. Additionally or alternatively, the microproppant coke particles can comprise (e.g., consist of, consist essentially of, or consist of) screened fluid coke, screened flexicoke, screened delayed coke, screened thermally post-treated coke, screened pyrolysis coke, and / or screened coal-derived coke (e.g., screened blast furnace coke and / or screened metallurgical coke). Additionally or alternatively, the microproppant coke particles can comprise (e.g., consist of, consist essentially of, or consist of) ground fluid coke, ground flexicoke, ground delayed coke, ground thermally post-treated coke, ground pyrolysis coke, and / or ground coal-derived coke (e.g., ground blast furnace coke and / or ground metallurgical coke). Further, any other suitable type of coke can be used additionally or alternatively. Such coke can be screened, ground, crushed, pulverized, and / or otherwise processed to produce coke fines of appropriate size to be characterized as the microproppant coke particles described herein.

[0072] In some embodiments, the microproppant coke particles included in the fracturing fluid can comprise, consist essentially of, or consist of: wet and / or dry flexicoke fines. Such flexicoke fines are by-products of the FLEXICOKING TM process, which are collected as particles not recovered in the secondary cyclone of the heater within the flexicoker. More specifically, the particles are first collected as dry flexicoke fines in the tertiary cyclone and then the smaller particles passing through the tertiary cyclone are recovered as wet flexicoke fines in a venturi scrubber. Although at least a portion of such wet and dry flexicoke fines would typically be considered waste according to current technology, the present disclosure provides for the effective utilization of such wet and dry flexicoke fines during hydraulic fracturing operations.

[0073] The fine petroleum coke particles that can be used as micro - proppant coke particles according to the embodiments described herein can have an average particle size distribution of 10 μm to 27 μm. Additionally, in some embodiments, the average particle size distribution of the fine petroleum coke particles is in the range of about 14 μm to about 23 μm. In other embodiments, exemplary ranges of the average particle size distribution of the fine petroleum coke particles include about 10 μm to about 12 μm, about 12 μm to about 14 μm, about 14 μm to about 16 μm, about 16 μm to about 18 μm, about 18 μm to about 20 μm, and about 20 μm to about 23 μm. As an example, for embodiments in which wet flexible coke fines are used as micro - proppant coke particles, such particles can have a D50 of about 22 μm (meaning 50% of the particles are less than about 22 μm), a D10 of about 5 μm (meaning 10% of the particles are less than about 5 μm), and a D90 of about 112 μm (meaning 90% of the particles are less than about 112 μm). As another example, for embodiments in which dry flexible coke fines are used as micro - proppant coke particles, such particles can have a D50 of about 15 μm (meaning 50% of the particles are less than about 15 μm), a D10 of about 6 μm (meaning 10% of the particles are less than about 6 μm), and a D90 of about 94 μm (meaning 90% of the particles are less than about 94 μm). More generally, wet flexible coke fines can have an average particle size of 20 μm to 24 μm, while dry flexible coke fines can have an average particle size of 13 μm to 17 μm.

[0074] In various embodiments, the micro - proppant coke particles described herein have an apparent density of 1.0 g / cm 3 to 2.0 g / cm 3 , or in some embodiments, an apparent density of about 1.4 g / cm 3 to about 1.7 g / cm 3 , but the exact apparent density of the particles can vary depending on the specific type(s) of coke used. In various embodiments, the average apparent density of the micro - proppant coke particles is about 1.6 g / cm 3 . Other exemplary ranges of the apparent density of the micro - proppant coke particles include about 1.0 g / cm 3 to about 1.2 g / cm 3 , about 1.2 g / cm 3 to about 1.4 g / cm 3 , about 1.4 g / cm 3 to about 1.6 g / cm 3 , about 1.6 g / cm 3 to about 1.8 g / cm 3 , about 1.8 g / cm 3 to about 2.0 g / cm 3 , about 1.0 g / cm 3 to about 1.4 g / cm3 , about 1.4 g / cm 3 to about 1.8 g / cm 3 , about 1.0 g / cm 3 to about 1.5 g / cm 3 and about 1.5 g / cm 3 to about 2.0 g / cm 3 , to give a few non - limiting examples. In contrast, sand typically has an apparent density of about 2.5 g / cm 3 or higher. Thus, because the settling rate is proportional to the density difference between the solid particles and the carrying fluid (as shown by the expressions for both Stokes' terminal settling velocity and Ferguson & Church settling velocity), the micro - proppant coke particles described herein have a significantly lower settling rate than sand. As a result, in terms of transport capacity within the fractures generated during a hydraulic fracturing operation, the micro - proppant coke particles described herein will perform better than the proppant particles formed from sand.

[0075] In various embodiments, the micro - proppant coke particles described herein are used as part of a fracturing fluid. In addition to the micro - proppant coke particles described herein, the fracturing fluid further comprises a flowable carrying fluid, (optionally) one or more additives, (optionally) other coke particles that are not sized to be characterized as micro - proppant coke particles, and (optionally) one or more other types of proppant particles. Other coke particles that are not sized to be characterized as micro - proppant coke particles (which may sometimes be interchangeably referred to herein as "second coke particles" or the "second portion" of the coke particles in the fracturing fluid) can include, but are not limited to, fluid coke particles, flexible coke particles, delayed coke particles, post - heat - treated coke particles, pyrolytic coke particles, and / or coal - derived coke particles (such as blast furnace coke particles and / or metallurgical coke particles). Such second coke particles can have a particle size greater than 105 μm.

[0076] One or more other types of proppant particles (which are sometimes referred to herein as "third proppant particles" or "non - coke particles") can include, but are not limited to, non - coke proppant particles (such as 100 - mesh sand), LWP particles, ULWP particles, and / or any other suitable type of commercially available proppant particles different from coke particles. Additionally, according to the embodiments described herein, the micro - proppant coke particles are designed to preferentially settle at least partially within secondary fractures in a subterranean formation (in addition to the primary fracture(s) in the subterranean formation), while the second coke particles and the third proppant particles are designed to preferentially settle within the primary fracture(s) in the subterranean formation.

[0077] In various embodiments, during a hydraulic fracturing process, fracturing fluid is formulated at the wellsite during a mixing process that occurs concurrently with pumping the fracturing fluid into the wellbore. When formulating fracturing fluid at the wellsite, microproppant coke particles can be added in a manner similar to known methods of adding proppant to fracturing fluid.

[0078] The carrier fluid according to the present technology can be an aqueous carrier including water or a non-aqueous carrier fluid substantially free of water. The aqueous carrier fluid can include, for example, fresh water, brine (including seawater), treated water (e.g., treated produced water), one or more other forms of aqueous fluid, or any combination thereof. One class of aqueous carrier fluid is commonly referred to as slickwater, and the corresponding fracturing operation is commonly referred to as a slickwater fracturing operation. The non-aqueous carrier fluid can include, for example, oil-based fluids (e.g., hydrocarbons, olefins, mineral oils), alcohol-based fluids (e.g., methanol), or any combination thereof. In various embodiments, the viscosity of the carrier fluid can be altered by foaming or gelling. Foaming can be achieved using, for example, air or other gases (e.g., CO2, N2) alone or in combination. Gelation can be achieved using, for example, guar gum (e.g., hydroxypropyl guar gum), cellulose, or other gelling agents, which can or cannot be crosslinked using one or more crosslinking agents such as polyvalent metal ions or borate anions and other suitable crosslinking agents.

[0079] In some cases, the carrier fluid used in the hydraulic fracturing of horizontal wells includes one or more types of aqueous carrier fluids, especially considering the large amounts of fluid typically required for hydraulic fracturing (e.g., about 60,000 to about 1,000,000 gallons per wellbore). The aqueous carrier fluid can be gelled or can be non-gelled. Using a gelled aqueous carrier fluid (crosslinked or uncrosslinked) can facilitate better proppant particle transport (i.e., reduced settling), as well as provide improved physical and chemical strength to withstand the temperature, pressure, and shear stresses encountered by the fracturing fluid during the hydraulic fracturing operation. In some cases, the fracturing fluid includes an aqueous carrier fluid (which can be or can be non-foamed or gelled) and an acid (e.g., HCl) to further stimulate and enlarge the pore area of the fracture surface matrix. It goes without saying that the low density of the microproppant coke particles described herein can allow for a reduction or elimination of the need to foam or gel the carrier fluid. Additionally, certain fracturing fluids suitable for use according to the embodiments described herein can contain one or more additives. Such additives can include, but are not limited to, one or more acids, one or more biocides, one or more breakers, one or more corrosion inhibitors, one or more crosslinking agents, one or more friction reducers (e.g., polyacrylamide), one or more gels, one or more deoxidizers, one or more pH control additives, one or more scale inhibitors, one or more surfactants, one or more weighting agents, one or more inert solids, one or more fluid loss control agents, one or more emulsifiers, one or more emulsion diluents, one or more emulsion thickeners, one or more viscosifiers, one or more foaming agents, one or more stabilizers, one or more chelating agents, one or more mutual solvents, one or more oxidizing agents, one or more reducing agents, one or more clay stabilizers, or any combination thereof.

[0080] In some embodiments, in addition to or as an alternative to the above-described conventional types of carrier fluids, the carrier fluid is liquid carbon dioxide (CO2) and / or supercritical CO2. While fracturing fluids comprising liquid and / or supercritical CO2 are capable of creating complex fracture networks within subterranean formations, the use of CO2 for hydraulic fracturing operations is limited due to the poor ability of CO2 to effectively transport proppants over long distances. However, due to the smaller particle size of the microproppant coke particles described herein, the microproppant coke particles are particularly suitable for effective transport within a CO2-based carrier fluid. Accordingly, in some embodiments, the methods described herein include utilizing liquid and / or supercritical CO2 as at least a portion of the carrier fluid for the fracturing fluid described herein during at least a portion of a hydraulic fracturing operation for an unconventional reservoir.

[0081] The present disclosure provides a method of hydraulically fracturing a subterranean formation using a fracturing fluid comprising the microproppant coke particles described herein. Such microproppant coke particles may optionally be used in combination with other coke particles that are not sized to be characterized as microproppant coke particles (i.e., the second coke particles described above) and / or one or more types of non-coke particles (i.e., the third proppant particles described above). Thus, depending on the details of a particular implementation, the microproppant coke particles may form the entirety or an integral part of the proppant pack.

[0082] In addition, in addition to or in place of the second coke particles and third proppant particles described herein, one or more other types of proppant particles comprising other materials may be included in the fracturing fluid described herein with the microproppant coke particles, provided that any such selected proppant particles are capable of maintaining their integrity when the water pressure within the induced fracture is removed such that when subjected to a stress of 5000 psi (a condition that the microproppant coke particles described herein must also meet), about 80%, preferably about 90%, more preferably about 95% or greater of the particulate mass of the other proppant particles remains intact. That is, the microproppant coke particles and any other type(s) of proppant particles used in accordance with the methods described herein maintain mechanical integrity upon fracture closure because the two types of particles are (at least partially) mixed or otherwise associated to form a functional proppant pack for a successful hydraulic fracturing operation.

[0083] The methods described herein include the preparation of the fracturing fluid, which is not considered to be particularly limited because the microproppant coke particles can be transported from the manufacturing site (e.g., an oil refinery or a synthetic fuel plant) in dry form or as part of a wet slurry. The dry and wet forms can be transported by truck or rail, and the wet form can be further transported via pipeline. The transported dry or wet microproppant coke particles can be added directly to the wellbore at the production site or added to a carrier fluid containing optional additives by premixing in a hopper or other mixing device. For example, in some embodiments, a small mass of dry or wet microproppant coke particles (or some combination of microproppant coke particles and other coke particles) can be added directly to the fracturing fluid (e.g., as it is introduced into the wellbore). In other embodiments, for example, when other type(s) of proppant particles (e.g., the second coke particles and / or the third proppant particles) are combined with the microproppant coke particles, a portion or all of the fracturing fluid can be premixed at the production site, or each proppant type can be added directly to the fracturing fluid individually. Without departing from the scope of the present disclosure, any other suitable mixing or addition of the microproppant coke particles can also be used to produce the desired fracturing fluid composition.

[0084] A suitable hydraulic fracturing method according to the embodiments described herein involves pumping a fracturing fluid containing micro - proppant coke particles into a subterranean formation at a high pumping rate to form one or more primary fractures and one or more secondary fractures extending from the primary fractures. In a preferred embodiment, such a process is carried out one stage at a time along the wellbore. The stage is hydraulically isolated from any other stage that has been previously fractured. In some embodiments, the fractured stage has perforation clusters that allow the fracturing fluid to flow through the metal tubular casing of the wellbore into the formation. This metal tubular casing is installed as part of the well completion when the wellbore is drilled and is used to provide mechanical integrity to the wellbore. In some embodiments, during one or more durations of the hydraulic fracturing operation, the pumping rate of the fracturing fluid during the hydraulic fracturing operation is at least about 20 barrels per minute (bbl / min) (0.05 cubic meters per second (m 3 / s)), preferably about 30 bbl / min (0.08 m 3 / s), more preferably at least 50 bbl / min (0.14 m 3 / s) and at most 1000 bbl / min (2.73 m 3 / s) (e.g., the rate can be constant, steadily increasing, or pulsed). In some embodiments, these high rates can be utilized after about 10% of the total volume of the fracturing fluid to be pumped into the formation has been injected. That is, in the early stages of the hydraulic fracturing operation, the pump rate can be reduced and as the fractures begin to form, the pump rate can be increased. Generally, the average pumping rate of the fracturing fluid throughout the operation can be about 10 bbl / min (0.03 m 3 / s), preferably about 15 bbl / min (0.04 m 3 / s), more preferably at least 25 bbl / min (0.07 m 3 / s) and at most 250 bbl / min (0.68 m 3 / s). Generally, during the fracturing operation for more than 30% of the time required for complete fracturing of the stage, the pumping rate of the fracturing fluid is between about 20 bbl / min (0.05 m 3 / s) and about 150 bbl / min (0.41 m 3 / s) (e.g., 20, 60, 90 bbl / min to 120, 150 bbl / min), or about 40 bbl / min (0.11 m 3 / s) and about 120 bbl / min (0.33 m 3 / s) (e.g., 40, 50, 60, 90 bbl / min to 100, 100, 120 bbl / min), or about 40 bbl / min (0.11 m 3 / s) to about 100 bbl / min (0.27 m 3 / s) (e.g., 40, 50, 60 bbl / min to 80, 90, 100 bbl / min).

[0085] In various embodiments, the hydraulic fracturing method described herein is performed such that, while the fracturing operation is being carried out, the concentration of microproppant coke particles and optionally the concentration(s) of a second coke particle and / or an optional third proppant particle(s) in the injected fracturing fluid is / are varied during operation such that the water pressure is maintained within the formation and the fracture(s). For example, in some embodiments, the initially injected fracturing fluid is injected at a low pumping rate and contains about 1 weight percent (wt%) of proppant particles (i.e., contains microproppant coke particles, optionally other coke particles, and optionally one or more other types of proppant particles), based on the total weight of the fracturing fluid (i.e., including the carrier fluid). When one or more fractures begin to form and grow, the pump rate can be increased and the concentration of proppant particles can be increased in a stepwise manner (with or without a stepwise increase in the pumping rate), where, for example, the maximum concentration of total proppant particles reaches about 2.5 wt% to about 20 wt%, based on the total weight of the fracturing fluid. For example, the maximum concentration of total proppant particles can reach at least 2.5 wt%, preferably about 8 wt%, more preferably about 16 wt%. In some embodiments, all proppant particles are coke particles, including both microproppant coke particles and second coke particles, if any second coke particles are present. In other embodiments, during one or more time periods of the hydraulic fracturing operation, at least about 2 wt% to about 100 wt% of any proppant particles suspended in the fracturing fluid are coke particles, such as at least about 2 wt%, preferably about 15 wt%, more preferably about 25 wt%, and even more preferably 100 wt%. Other exemplary values of coke particles suspended in the fracturing fluid include about 10 wt%, about 20 wt%, about 30 wt%, about 40 wt%, about 50 wt%, about 60 wt%, about 70 wt%, about 80 wt%, and about 90 wt%.

[0086] In various embodiments, microproppant coke particles are introduced into a subterranean formation during at least a portion of the pad phase of a fracturing operation to allow the microproppant coke particles to travel with the fracturing fluid into the tips of the primary and secondary fractures formed (or at least near the tips). In such embodiments, the microproppant coke particles may also be introduced into the formation during at least a portion of a later stage of the fracturing operation such that the slurry of the later-introduced fracturing fluid and microproppant coke particles (optionally combined with second coke particles and / or third proppant particles) continues to displace the slurry of the earlier-introduced fracturing fluid and microproppant coke particles further away from the wellbore. Additionally, in some embodiments, the microproppant coke particles are introduced into the formation continuously or intermittently throughout the fracturing operation. In such embodiments, the ratio of microproppant coke particles to second coke particles, the ratio of microproppant coke particles to third proppant particles, and / or the ratio of microproppant coke particles to both second coke particles and third proppant particles may optionally be maintained at a stable (or substantially stable) value.

[0087] The hydraulic fracturing methods described herein may be performed in drilled horizontal, vertical, or deviated wellbores (including hydrocarbon-producing (e.g., oil and / or gas) wellbores and / or water-producing wellbores). Such wellbores may be drilled into various types of formations, including but not limited to, shale formations, oil sand formations, gas sand formations, and the like.

[0088] Wellbores are typically completed using metal (e.g., steel) pipe or casing cemented into the subterranean formation. To access the formation, multiple perforations are created through the pipe and cement along the section to be treated, commonly referred to as a plug and perf ("plug and perf") casing hole completion. Without departing from the scope of the present disclosure, alternative completion techniques may be used, but in each completion technique, a limited length of the wellbore is exposed for hydraulic fracturing and injection of the fracturing fluid. This limited section is referred to herein as a "stage". The complete completion of a horizontal well typically includes multiple stages of hydraulic fracturing performed sequentially. In a plug and perf completion, the stage length may be based on the distance over which the pipe and cement have been perforated and may range, for example, from about 10 feet (ft) (3 meters (m)) to about 2000 ft (610 m), and more generally from about 100 ft (30.5 m) to about 300 ft (91.4 m). The stage is isolated (e.g., using a sliding sleeve or a frac plug and ball) such that pressurized fracturing fluid from the surface can flow through the perforations and into the formation to create one or more fractures only in the stage area. Perforation clusters may be used to facilitate the initiation of multiple fractures. For example, the perforation clusters may be made in a section of the stage that is about 1 ft (0.3 m) to about 3 ft (0.9 m) in length and spaced about 10 ft (3 m) to about 50 ft (15.2 m) apart.

[0089] For each linear foot of the stage, at least about 6 barrels (0.95 cubic meters (m 3 )) can be injected, preferably about 24 barrels (3.8 m 3 ), more preferably at least 60 barrels (9.5 m 3 ) and at most 6000 barrels (953.9 m 3 ) of fracturing fluid to grow the fracture. In certain embodiments, for each linear foot of the stage, at least about 0.05 m 3 can be injected, preferably at least about 0.18 m 3 , more preferably at least 0.45 m 3 and at most 45.3 m 3 , or at most 22.7 m 3 , or at most 18.1 m 3 of proppant particles (i.e., including microproppant coke particles, optional second coke particles, and optional third proppant particles) to prop the fracture.

[0090] Certain commercial operations, such as commercial shale fracturing operations, may be particularly suitable for hydraulic fracturing using the micro - proppant coke particles described herein because the mass of the total proppant particles required for each stage in such operations can be quite large, and significant economic benefits can be obtained by using the micro - proppant coke particles described herein to support the extended area of the fracture. The cost of the coke particles can be lower than the cost of sand and significantly lower than the cost of currently available micro - proppants, which provides significant economic benefits. In fact, in some cases, the stages in a shale formation can be designed to require at least about 30,000 pounds (mass), preferably at least about 100,000 pounds (mass), more preferably at least about 250,000 pounds (mass) of total proppant particles. In such cases, when at least 3 wt% of the total weight of the coke particles in the fracturing fluid (e.g., in some embodiments, 5 wt% to 100 wt%, 10 wt% to 90 wt%, 30 wt% to 80 wt%, 40 wt% to 70 wt% or 50 wt% to 60 wt%) comprises the micro - proppant coke particles described herein, the economic and performance benefits can be optimized. For example, for embodiments in which the micro - proppant coke particles described herein are included in the fracturing fluid during the pad phase, during the pad phase of each stage, the fracturing fluid may contain from about 200 pounds to about 15,000 pounds, or from about 500 pounds to about 10,000 pounds, or from about 1,000 pounds to about 7,500 pounds, or from about 2,000 pounds to 50,000 pounds of micro - proppant coke particles, depending in part on the concentration of the micro - proppant coke particles in the fracturing fluid compared to the total weight of the coke particles (or, in some cases, the total weight of all proppant particles) (where 3 wt%, 33 wt% and 100 wt% are used as representative concentration values in this example). However, for slurry - only and two - stage embodiments in which the micro - proppant coke particles described herein are included in the fracturing fluid during the slurry phase, during the hydraulic fracturing of each stage, the fracturing fluid may contain from about 900, 1000, 2000, 3000, 4000, 5000 pounds to about 7000, 7500, 8000, 8500, 9000, 10,000 pounds to about 20,000, 40,000, 50,000, 60,000, 80,000, 90,000, 100,000 pounds to about 120,000, 150,000, 180,000, 200,000, 220,000, 240,000, 250,000 pounds of micro - proppant coke particles, depending in part on the concentration of the micro - proppant coke particles in the fracturing fluid compared to the total weight of the coke particles (or in some cases, the total weight of all proppant particles) (in this example, 3 wt%, 33 wt% and 100 wt% are used as representative concentration values).In addition, as described herein, it is economically viable to utilize such a large amount of the micro - proppant coke particles described herein, due to the lower cost of such coke particles compared to other commercially available micro - proppant particles.

[0091] In addition, typically, multiple stages of a wellbore are isolated and hydraulic fracturing is performed on each stage. The micro - proppant coke particles described herein can be used in any number of stages, including for example at least 2 stages, preferably at least 10 stages, more preferably at least 20 stages.

[0092] Figure 4 is a process flow diagram of an exemplary method 400 of utilizing the fracturing fluid described herein during a hydraulic fracturing operation. Method 400 can start at optional blocks 402, 404, and / or 406. Specifically, at optional block 402, micro - proppant coke particles having a particle size of at most 105 μm (140 mesh) are produced by extracting wet flexicoke fines and / or dry flexicoke fines from a FLEXICOKING TM process, as described herein. In some embodiments, the micro - proppant coke particles have a particle size of at most 88 μm (170 mesh). For some embodiments in which wet flexicoke fines are produced, such wet flexicoke fines can have a median particle size of 8 μm to 22 μm. Other exemplary ranges for the median particle size of wet flexicoke fines include from about 8 μm to about 10 μm, from about 10 μm to about 12 μm, from about 12 μm to about 14 μm, from about 14 μm to about 16 μm, from about 16 μm to about 18 μm, from about 18 μm to about 20 μm, and from about 20 μm to about 22 μm, to give some non - limiting examples. For some embodiments in which dry flexicoke fines are produced, such dry flexicoke fines can have a median particle size of 6 μm to 16 μm. Other exemplary ranges for the median particle size of dry flexicoke fines include from about 6 μm to about 8 μm, from about 8 μm to about 10 μm, from about 10 μm to about 12 μm, from about 12 μm to about 14 μm, and from about 14 μm to about 16 μm, to give some non - limiting examples. In various embodiments, the wet and / or dry flexicoke fines have an apparent density of 1.0 g / cm 3 to 2.0 g / cm 3 (or in some embodiments, in the range of 1.4 g / cm 3 to 1.7 g / cm 3 ). Other exemplary ranges for the apparent density of the wet and / or dry flexicoke fines include from about 1.0 g / cm 3 to about 1.2 g / cm 3 , from about 1.2 g / cm 3 to about 1.4 g / cm 3 , from about 1.4 g / cm 3to about 1.6 g / cm 3 、about 1.6 g / cm 3 to about 1.8 g / cm 3 and about 1.8 g / cm 3 to about 2.0 g / cm 3 , to list a few non-limiting examples.

[0093] Additionally or alternatively, at optional block 404, microproppant coke particles having a particle size of up to 105 μm (140 mesh) are produced by screening fluid coke, flexible coke, delayed coke, post-heated coke, pyrolysis coke, coal-derived coke (such as blast furnace coke and / or metallurgical coke) and / or any other suitable type(s) of coke. In some embodiments, the microproppant coke particles have a particle size of up to 88 μm (170 mesh). In particular, sieves, filters, screens, and / or related mechanical equipment are used to separate bulk coke granules of any suitable type(s) into larger and smaller particles suitable for use as the microproppant coke particles described herein. In various embodiments, the screened fluid coke particles, screened flexible coke particles, screened delayed coke particles, screened post-heated coke particles, screened pyrolysis coke particles, and / or screened coal-derived coke (e.g., screened blast furnace coke and / or screened metallurgical coke) have an apparent density of 1.0 g / cm 3 to 2.0 g / cm 3 . Further, in some embodiments, the screened fluid coke particles, screened flexible coke particles, screened delayed coke particles, screened post-heated coke particles, screened pyrolysis coke particles, and / or screened coal-derived coke (e.g., screened blast furnace coke and / or screened metallurgical coke) have a median particle size of 76 μm to 86 μm.

[0094] Additionally or alternatively, at optional block 406, micro - proppant coke particles having a particle size of up to 105 μm (140 mesh) are produced by grinding fluid coke, flexible coke, delayed coke, heat - treated coke, pyrolysis coke, coal - derived coke (such as blast furnace coke and / or metallurgical coke) and / or any other suitable type(s) of coke. In some embodiments, the micro - proppant coke particles have a particle size of up to 88 μm (170 mesh). Any suitable type(s) of grinding / milling technique(s) can be used for this purpose. For example, in some embodiments, hammer - milling techniques, jet - milling techniques, ball - milling techniques, etc. can be used to process the coke particles, where each of these techniques generally involves crushing or pulverizing the coke particles into a suitable size and shape. Additionally, those skilled in the art will understand that depending on the details of the particular implementation, any number of other grinding, milling, or other processing techniques can be used additionally or alternatively. In various embodiments, the ground fluid coke particles, ground flexible coke particles, ground delayed coke particles, ground heat - treated coke particles, ground pyrolysis coke particles, ground and / or ground coal - derived coke particles (e.g., ground blast furnace coke particles and / or ground metallurgical coke particles) have an apparent density of 1.0 g / cm 3 to 2.0 g / cm 3 of apparent density.

[0095] At block 408, a fracturing fluid comprising a carrier fluid and coke particles is introduced into a subterranean formation (i.e., via injection through a wellbore during a hydraulic fracturing operation). The coke particles include the micro - proppant coke particles described herein (optionally produced as at blocks 402, 404, and / or 406). The micro - proppant coke particles are provided in the fracturing fluid at a concentration of at least 3 wt%, based on the total weight of the coke particles in the fracturing fluid (where the weight percentage of the particles can be determined before mixing the particles with the carrier fluid, e.g., based on dry particles). In some embodiments, the micro - proppant coke particles are provided in the fracturing fluid at a concentration of 5 wt% to 100 wt%, or in some cases, 30 wt% to 80 wt%, based on the total weight of the coke particles in the fracturing fluid. However, the exact concentration of the micro - proppant coke particles in the fracturing fluid will vary depending on the details of the particular implementation. Additionally, based on the volume of the carrier fluid, the coke particles have a total concentration in the fracturing fluid of about 14 kg / m³ to about 480 kg / m³. In some embodiments, based on the volume of the carrier fluid, the coke particles have a total concentration of about 18 kg / m³ to about 120 kg / m³. In some embodiments, based on the volume of the carrier fluid, the coke particles have a total concentration of about 23 kg / m³ to about 96 kg / m³.

[0096] In some embodiments, fracturing fluid may be introduced into a subterranean formation during a first interval of a hydraulic fracturing operation, wherein the microproppant coke particles have a total concentration of at least 50 wt% (e.g., ≥60 wt%, ≥70 wt%, ≥80 wt%, ≥90 wt%, ≥95 wt% or even 100 wt%), based on the total weight of the coke particles in the fracturing fluid, and fracturing fluid may also be introduced into the subterranean formation during a second interval of the hydraulic fracturing operation, wherein the microproppant coke particles have a total concentration of at most 20 wt% (e.g., ≤15 wt%, ≤10 wt%, ≤8 wt%, ≤5 wt% and as low as 3 wt%), based on the total weight of the coke particles in the fracturing fluid. The first interval is preferably in front of the second interval. The first interval may advantageously be part or all of a pad phase. The second interval may advantageously be part or all of a slurry phase. Due to the low density and small size of the microproppant coke particles, they can be successfully transported into the fractures (including primary and secondary fractures) created in the early first interval without causing screen-out of the fractures. In the later second interval, the microproppant coke particles dispersed in the various fractures during the first interval and the additional microproppant coke particles introduced during the second interval can be further transported into the additional and more primary and secondary fractures created during the second interval.

[0097] In other embodiments, fracturing fluid may be introduced into a subterranean formation during a first interval of a hydraulic fracturing operation, wherein the micro - proppant coke particles have a total concentration of at least 50 wt% (e.g., ≥60 wt%, ≥70 wt%, ≥80 wt%, ≥90 wt%, ≥95 wt% or even 100 wt%), based on the total weight of the coke particles in the fracturing fluid, and a second fracturing fluid may be introduced into the subterranean formation during a second interval of the hydraulic fracturing operation, wherein the second fracturing fluid comprises a carrier fluid and second coke particles, and the second coke particles comprise a total concentration of less than 3 wt% (e.g., ≤2.5 wt%, ≤2.0 wt%, ≤1 wt% or even 0 wt%) of micro - proppant coke particles, based on the total weight of the second coke particles in the second fracturing fluid. The first interval is preferably before the second interval. The first interval may advantageously be part or all of a pad phase. The second interval may advantageously be part or all of a slurry phase. Due to the low density and small size of the micro - proppant coke particles, they can be successfully transported into the fractures (including primary and secondary fractures) created during the earlier first interval without causing screen - out of the fractures. In the later second interval, the micro - proppant coke particles dispersed in the various fractures during the first interval can be further transported into additional and more primary and secondary fractures created during the second interval, such that no further introduction of any substantial amount of micro - proppant coke particles is required during the second interval. Such particularly advantageous embodiments include: (i) during the pad phase, injecting into the wellbore a fracturing fluid containing only micro - proppant coke particles to create a pad having initial primary and secondary fractures containing micro - proppant coke particles; and (ii) during a subsequent slurry phase, injecting into the pad formed in the pad phase a second fracturing fluid substantially free of micro - proppant coke particles and containing coke particles having a size greater than 105 μm, thereby creating additional primary and secondary fractures and further transporting the micro - proppant coke particles dispersed in the initial fractures into the additional primary and secondary fractures.

[0098] In some embodiments, the carrier fluid is an aqueous carrier fluid that contains water. In other embodiments, the carrier fluid is a non-aqueous carrier fluid that is substantially free of water. In other embodiments, the carrier fluid is liquid and / or supercritical CO2. Further, in various embodiments, the fracturing fluid further comprises one or more additives, such as one or more acids, one or more biocides, one or more breaker agents, one or more corrosion inhibitors, one or more crosslinking agents, one or more friction reducers (e.g., polyacrylamide), one or more gels, one or more deoxidizers, one or more pH control additives, one or more scale inhibitors, one or more surfactants, one or more weighting agents, one or more inert solids, one or more fluid loss control agents, one or more emulsifiers, one or more emulsion diluents, one or more emulsion thickeners, one or more viscosifiers, one or more foaming agents, one or more stabilizers, one or more chelating agents, one or more mutual solvents, one or more oxidizing agents, one or more reducing agents, one or more clay stabilizers, or any combination thereof.

[0099] In various embodiments, at least a portion of the microproppant coke particles is deposited within secondary fractures in a subterranean formation. Specifically, according to the embodiments described herein, while a portion of the microproppant coke particles will likely be deposited within the primary fracture(s), the microproppant coke particles are specifically designed to preferentially travel into and deposit within the secondary fractures as well as the primary fracture(s). This is at least in part due to the smaller particle size and lower density of such microproppant coke particles and the corresponding enhanced transport properties compared to other types of proppant particles. Further, in various embodiments, method 400 includes introducing a fracturing fluid into the subterranean formation during at least a portion of the pad phase of a hydraulic fracturing operation and then introducing a second fracturing fluid comprising a carrier fluid and the second coke particles and / or the third proppant particles described herein during, for example, the slurry phase following the pad phase.

[0100] In other embodiments, the fracturing fluid itself comprises second coke particles (e.g., a second portion of coke particles having a particle size greater than 105 μm). Such second coke particles can include, but are not limited to, fluid coke particles, flexible coke particles, delayed coke particles, post-thermally treated coke particles, pyrolysis coke particles, and / or coal-derived coke particles (e.g., blast furnace coke particles and / or metallurgical coke particles) as described herein. In such embodiments, method 400 can include introducing a fracturing fluid comprising microproppant coke particles and second coke particles into a subterranean formation during at least a portion of the pad phase of a hydraulic fracturing operation and during at least a portion of the remainder of the hydraulic fracturing operation. Method 400 can also include preferentially depositing at least a portion of the microproppant coke particles within secondary fractures in the subterranean formation and preferentially depositing the second coke particles within the primary fracture(s) in the subterranean formation.

[0101] Additionally or alternatively, in some embodiments, the fracturing fluid itself comprises third proppant particles as described herein. Such third proppant particles can include, but are not limited to, sand and / or other types of non-coke proppant particles, LWP particles, and / or ULWP particles as described herein. In such embodiments, method 400 can include introducing a fracturing fluid comprising microproppant coke particles and third proppant particles into a subterranean formation during at least a portion of the pad phase of a hydraulic fracturing operation and during at least a portion of the remainder of the hydraulic fracturing operation. Method 400 can also include preferentially depositing at least a portion of the microproppant coke particles within secondary fractures in the subterranean formation and preferentially depositing the third proppant particles within the primary fracture(s) in the subterranean formation.

[0102] Furthermore, in various embodiments, the fracturing fluid is introduced into the subterranean formation via stages of a hydrocarbon well. In such embodiments, method 400 also includes repeating block 408 for each of a plurality of additional stages of the hydrocarbon well, such as at least 2 stages, preferably at least 10 stages, more preferably at least 20 stages, and in some cases, all stages of the hydrocarbon well.

[0103] Those skilled in the art will understand that Figure 4 the exemplary method 400 is amenable to modification without changing the technical effects provided by the present disclosure. In practice, the precise manner of performing method 400 will depend at least in part on the details of the particular implementation.

[0104] Figure 5It is a process flow diagram of an exemplary method 500 for preparing the fracturing fluid described herein. Method 500 begins at block 502, where a first collection of coke particles is provided that includes micro - proppant coke particles having a particle size of up to 105 μm (140 mesh). In some embodiments, the particle size of the micro - proppant coke particles is up to 88 μm (170 mesh).

[0105] At block 504, a fracturing fluid is provided by mixing the micro - proppant coke particles with a carrier fluid and an optional second collection of proppant particles, wherein based on the total weight of the coke particles included in the first collection of coke particles and the second collection of proppant particles, the total concentration of micro - proppant coke particles in the fracturing fluid is at least 3 wt%, and the mass of the coke particles is from about 14 kg / m³ to about 240 kg / m³ relative to the volume of the carrier fluid. Such mixing can be carried out at the production site, directly into the wellbore or by pre - mixing in a hopper or other mixing equipment. Any suitable type of mixing equipment can be used for this purpose, depending on the details of the particular implementation.

[0106] In various embodiments, the second collection of proppant particles includes non - coke particles (e.g., the third proppant particles described herein) and / or second coke particles that are different from the coke particles within the first collection of coke particles. In such embodiments, the non - coke particles can include, but are not limited to, sand, LWP, and / or ULWP. Additionally, in such embodiments, the second coke particles can have a particle size greater than 105 μm. Further, in various embodiments, the first collection of coke particles can be substantially free of second coke particles having a particle size greater than 105 μm.

[0107] In some embodiments, in addition to the micro - proppant coke particles, the first collection of coke particles further includes coke particles having a particle size greater than 105 μm. In some embodiments, block 504 includes mixing the first collection of coke particles, the carrier fluid, and the optional second collection of proppant particles with one or more additives. In such embodiments, such additive(s) can include, but are not limited to, acids, biocides, breaker agents, corrosion inhibitors, cross - linkers, friction reducers, gels, deoxidizers, pH control additives, scale inhibitors, surfactants, weighting agents, inert solids, fluid loss control agents, emulsifiers, emulsion diluents, emulsion thickeners, viscosifiers, foaming agents, stabilizers, chelating agents, mutual solvents, oxidizing agents, reducing agents, and / or clay stabilizers.

[0108] In some embodiments, the micro - proppant coke particles include petroleum coke fines, and the first coke particle collection includes petroleum coke particles. In such embodiments, the micro - proppant coke particles can include wet - flexible coke fines and / or dry - flexible coke fines. In such embodiments, method 500 can further include producing wet - flexible coke fines and / or dry - flexible coke fines via the FLEXICOKING TM process. Additionally or alternatively, in some embodiments, the micro - proppant coke particles include screened fluid coke, screened flexible coke, screened delayed coke, screened thermally - treated coke, screened pyrolysis coke, and / or screened coal - derived coke (e.g., screened blast furnace coke and / or screened metallurgical coke). In such embodiments, method 500 can also include screening fluid coke, flexible coke, delayed coke, thermally - treated coke, pyrolysis coke, and / or coal - derived coke (e.g., blast furnace coke and / or metallurgical coke) to provide micro - proppant coke particles having a particle size of up to 105 μm. Additionally or alternatively, in some embodiments, the micro - proppant coke particles include ground fluid coke, ground flexible coke, ground delayed coke, ground thermally - treated coke, ground pyrolysis coke, and / or ground coal - derived coke (e.g., ground blast furnace coke and / or ground metallurgical coke). In such embodiments, method 500 can also include grinding fluid coke, flexible coke, delayed coke, thermally - treated coke, pyrolysis coke, and / or coal - derived coke (e.g., blast furnace coke and / or metallurgical coke) to provide micro - proppant coke particles having a particle size of up to 105 μm.

[0109] In some embodiments, the carrier fluid includes an aqueous carrier fluid that includes water. In other embodiments, the carrier fluid includes a non - aqueous carrier fluid that is substantially free of water. In still other embodiments, the carrier fluid includes liquid CO2 and / or supercritical CO2.

[0110] Those skilled in the art will understand that Figure 5 the exemplary method 500 is amenable to modification without changing the technical effects provided by the present disclosure. In practice, the precise manner of performing method 500 will depend at least in part on the details of the particular implementation.

[0111] The present disclosure can include one or more of the following non - limiting aspects and / or embodiments:

[0112] A1. A fracturing fluid comprising a carrier fluid and coke particles, wherein the coke particles comprise micro - proppant coke particles having a particle size of at most 105 μm, and based on the total weight of the coke particles in the fracturing fluid, the micro - proppant coke particles have a total concentration of at least 3 wt%, and based on the volume of the carrier fluid, the coke particles have a total concentration in the fracturing fluid of from 14 kg / m³ to 480 kg / m³.

[0113] A1a. The fracturing fluid of A1, wherein based on the volume of the carrier fluid, the coke particles have a total concentration of from 18 kg / m³ to 120 kg / m³.

[0114] A1b. The fracturing fluid of A1, wherein based on the volume of the carrier fluid, the coke particles have a total concentration of from 23 kg / m³ to 96 kg / m³.

[0115] A2. The fracturing fluid of A1, wherein based on the total weight of the coke particles in the fracturing fluid, the micro - proppant coke particles have a total concentration of from 5 wt% to 100 wt%.

[0116] A3. The fracturing fluid of A1, wherein based on the total weight of the coke particles in the fracturing fluid, the micro - proppant coke particles have a total concentration of from 30 wt% to 80 wt%.

[0117] A4. The fracturing fluid of any one of A1 to A3, wherein the micro - proppant coke particles comprise petroleum coke fines, and wherein the coke particles comprise petroleum coke particles.

[0118] A5. The fracturing fluid of A4, wherein the micro - proppant coke particles comprise at least one of wet flexible coke fines and dry flexible coke fines.

[0119] A6. The fracturing fluid of A5, wherein the wet flexible coke fines have a median particle size of from 8 μm to 22 μm.

[0120] A7. The fracturing fluid of A5 or A6, wherein the dry flexible coke fines have a median particle size of from 6 μm to 16 μm.

[0121] A8. The fracturing fluid of any one of A4 to A7, wherein the micro - proppant coke particles comprise fluid coke particles.

[0122] A9. The fracturing fluid of any one of A1 to A8, wherein the micro - proppant coke particles have an apparent density of 1.0 g / cm 3 to 2.0 g / cm 3 of the apparent density.

[0123] A fracturing fluid according to any one of A1 to A9, wherein the micro - proppant coke particles comprise at least one of the following: screened fluid coke, screened flexible coke, screened delayed coke, screened heat - treated coke, screened pyrolytic coke, and screened coal - derived coke.

[0124] A fracturing fluid according to A11, wherein at least one of screened fluid coke, screened flexible coke, screened delayed coke, screened heat - treated coke, screened pyrolytic coke, and screened coal - derived coke has a median particle size of 76 μm to 86 μm.

[0125] A fracturing fluid according to any one of A1 to A11, wherein the micro - proppant coke particles comprise at least one of the following: ground fluid coke, ground flexible coke, ground delayed coke, ground heat - treated coke, ground pyrolytic coke, and ground coal - derived coke.

[0126] A fracturing fluid according to any one of A1 to A12, wherein the coke particles further comprise a second portion having a particle size greater than 105 μm.

[0127] A fracturing fluid according to A13, wherein the micro - proppant coke particles are designed to preferentially settle within secondary fractures in a subterranean formation in addition to primary fractures in the subterranean formation, and the second portion is designed to preferentially settle within primary fractures in the subterranean formation.

[0128] A fracturing fluid according to any one of A1 to A14, further comprising a third proppant particle different from the coke particles.

[0129] A fracturing fluid according to A15, wherein the third proppant particle comprises sand.

[0130] A fracturing fluid according to A15 or A16, wherein the third proppant particle comprises at least one of LWP and ULWP.

[0131] A fracturing fluid according to any one of A1 to A17, wherein the carrier fluid comprises water.

[0132] A fracturing fluid according to any one of A1 to A17, wherein the carrier fluid is substantially free of water.

[0133] A fracturing fluid according to any one of A1 to A19, wherein the carrier fluid comprises at least one of liquid CO2 and supercritical CO2.

[0134] A fracturing fluid according to any one of A21.A1 to A20, further comprising at least one of the following substances: acid, biocide, breaker, corrosion inhibitor, crosslinking agent, friction reducer, gel, deoxidizer, pH control additive, scale inhibitor, surfactant, weighting agent, inert solid, filtration control agent, emulsifier, emulsion diluent, emulsion thickener, viscosifier, foaming agent, stabilizer, chelating agent, mutual solvent, oxidizing agent, reducing agent, and clay stabilizer.

[0135] B1. A method, comprising: (I) introducing a fracturing fluid into a subterranean formation, the fracturing fluid comprising a carrier fluid and coke particles, wherein the coke particles comprise microproppant coke particles having a particle size of at most 105 μm at a concentration of at least 3 wt%, based on the total weight of the coke particles in the fracturing fluid; the coke particles have a total concentration in the fracturing fluid of 14 kg / m³ to 480 kg / m³, based on the volume of the carrier fluid.

[0136] B1a. The fracturing fluid of B1, wherein the coke particles have a total concentration of 18 kg / m³ to 120 kg / m³, based on the volume of the carrier fluid.

[0137] B1b. The fracturing fluid of B1, wherein the coke particles have a total concentration of 23 kg / m³ to 96 kg / m³, based on the volume of the carrier fluid.

[0138] B2. The method of B1, wherein the microproppant coke particles have a total concentration of 5 wt% to 100 wt%, based on the total weight of the coke particles in the fracturing fluid.

[0139] B3. The method of B1, wherein the microproppant coke particles have a total concentration of 30 wt% to 80 wt%, based on the total weight of the coke particles in the fracturing fluid.

[0140] B4. The method according to any one of B1 to B3, wherein the microproppant coke particles comprise petroleum coke fines, and wherein the coke particles comprise petroleum coke particles.

[0141] B5. The method of B4, wherein the microproppant coke particles comprise at least one of wet flexible coke fines and dry flexible coke fines.

[0142] B6. The method of B5, wherein the method further comprises producing at least one of wet flexible coke fines and dry flexible coke fines via the FLEXICOKING TM process.

[0143] B7. The method of B5 or B6, wherein the wet flexible coke fines have a median particle size of 8 μm to 22 μm.

[0144] A method according to any one of B8.B5 to B7, wherein the dry flexible coke fines have a median particle size of 6 μm to 16 μm.

[0145] A method according to any one of B9.B4 to B8, wherein the microproppant coke particles comprise fluid coke particles.

[0146] A method according to any one of B10.B1 to B9, wherein the microproppant coke particles have an apparent density of 1.0 g / cm 3 to 2.0 g / cm 3 of the apparent density.

[0147] A method according to any one of B11.B1 to B10, wherein the microproppant coke particles comprise at least one of the following: screened fluid coke, screened flexible coke, screened delayed coke, screened heat-treated coke, screened pyrolysis coke, and screened coal-derived coke.

[0148] A method according to B12.B11, wherein at least one of the screened fluid coke, screened flexible coke, screened delayed coke, screened heat-treated coke, screened pyrolysis coke, and screened coal-derived coke has a median particle size of 76 μm to 86 μm.

[0149] A method according to B13.B11 or B12, wherein the method further comprises screening at least one of fluid coke, flexible coke, delayed coke, heat-treated coke, pyrolysis coke, and coal-derived coke to obtain microproppant coke particles having a particle size of at most 105 μm.

[0150] A method according to any one of B14.B1 to B13, wherein the microproppant coke particles comprise at least one of the following: ground fluid coke, ground flexible coke, ground delayed coke, ground heat-treated coke, ground pyrolysis coke, and ground coal-derived coke.

[0151] A method according to B15.B14, wherein the method further comprises grinding at least one of fluid coke, flexible coke, delayed coke, heat-treated coke, pyrolysis coke, and coal-derived coke to obtain microproppant coke particles having a particle size of at most 105 μm.

[0152] A method according to any one of B16.B1 to B15, comprising introducing the fracturing fluid into a subterranean formation during the pad phase of a hydraulic fracturing operation, and then introducing a second fracturing fluid comprising a carrier fluid and at least one of the following into the subterranean formation: (i) second proppant particles comprising second coke particles but substantially free of the microproppant coke particles; and (ii) third proppant particles substantially free of coke particles.

[0153] A method according to any one of B17.B1 to B16, wherein the coke particles further comprise a second portion having a particle size greater than 105 μm.

[0154] A method according to B18.B17, wherein step (I) is carried out during the pad phase of a hydraulic fracturing operation.

[0155] A method according to B18a.B18, wherein the hydraulic fracturing fluid is substantially free of proppant particles having a particle size greater than 105 μm.

[0156] A method according to B18b.B18, wherein the fracturing fluid comprises the microproppant coke particles at a concentration of at least 80% by weight, based on the total weight of all microproppant particles present in the fracturing fluid.

[0157] A method according to B19.B1 to B18b, wherein the fracturing fluid further comprises a third proppant particle different from the coke particles.

[0158] A method according to B20.B19, wherein the third proppant particle comprises sand.

[0159] A method according to B21.B19 or B20, wherein the third proppant particle comprises at least one of LWP and ULWP.

[0160] A method according to B22.B19 to B21, wherein step (I) is carried out during the slurry phase of a hydraulic fracturing operation.

[0161] A method according to B22a.B22, wherein the hydraulic fracturing fluid further comprises a second coke particle having a particle size greater than 105 μm.

[0162] A method according to B22b.B22, wherein the fracturing fluid comprises the microproppant coke particles at a concentration of at most 10% by weight, based on the total weight of all coke particles present in the fracturing fluid.

[0163] A method according to B23.B1 to B22b, comprising a first interval and a second interval, wherein: during the first interval, the microproppant coke particles have a total concentration of at least 50% by weight, based on the total weight of the coke particles in the fracturing fluid; and during the second interval, the microproppant coke particles have a total concentration of at most 20% by weight, based on the total weight of the coke particles in the fracturing fluid.

[0164] A method according to any one of B24.B1 to B22b, comprising a first interval and a second interval, wherein: during the first interval, step (I) is carried out, wherein based on the total weight of the coke particles in the fracturing fluid, the micro - proppant coke particles have a total concentration of at least 50% by weight; and during the second interval, the following steps are carried out: introducing a second fracturing fluid comprising a carrier fluid and second coke particles, wherein the second coke particles comprise the micro - proppant coke particles at a total concentration of less than 3% by weight, based on the total weight of the second coke particles in the second fracturing fluid.

[0165] A method according to any one of B25.B1 to B24, wherein the carrier fluid comprises water.

[0166] A method according to any one of B26.B1 to B24, wherein the carrier fluid is substantially free of water.

[0167] A method according to any one of B27.B1 to B26, wherein the carrier fluid comprises at least one of liquid CO2 and supercritical CO2.

[0168] A method according to any one of B28.B1 to B27, wherein the fracturing fluid further comprises at least one of the following substances: acids, biocides, breaker agents, corrosion inhibitors, cross - linkers, friction reducers, gels, deoxygenating agents, pH control additives, scale inhibitors, surfactants, weighting agents, inert solids, filtration control agents, emulsifiers, emulsion diluents, emulsion thickeners, viscosifiers, foaming agents, stabilizers, chelating agents, mutual solvents, oxidizing agents, reducing agents, and clay stabilizers.

[0169] A method according to any one of B29.B1 to B28, wherein the fracturing fluid is introduced into a subterranean formation via a stage of a hydrocarbon well, and wherein the method further comprises repeating the introduction of the fracturing fluid and the deposition of at least a portion of the micro - proppant coke particles for each of a plurality of additional stages of the hydrocarbon well.

[0170] A method for preparing a fracturing fluid, comprising: providing a first collection of coke particles comprising micro - proppant coke particles, wherein the micro - proppant coke particles have a particle size of at most 105 μm; and mixing the first collection of coke particles with a carrier fluid and optionally a second collection of proppant particles, wherein based on the total weight of the coke particles contained in the first collection of coke particles and the second collection of proppant particles, the total concentration of the micro - proppant coke particles is at least 3% by weight; and the mass of the coke particles is from 14 kg / m3 to 240 kg / m3 relative to the volume of the carrier fluid.

[0171] A fracturing fluid according to C1a.C1, wherein the mass of the coke particles is from 18 kg / m3 to 120 kg / m3 relative to the volume of the carrier fluid.

[0172] A fracturing fluid of C1b.C1, wherein the mass of the coke particles is 23 kg / m³ to 96 kg / m³ relative to the volume of the carrier fluid.

[0173] A method of any one of C2.C1, C1a and C1b, wherein the particle size of the micro - proppant coke particles is at most 88 μm.

[0174] A method of C3.C1 or C2, wherein the second proppant particle collection contains at least one of non - coke particles and second coke particles different from the coke particles within the first coke particle collection.

[0175] A method of C4.C3, wherein the non - coke particles contain at least one of sand, LWP and ULWP.

[0176] A method of C5.C3 or C4, wherein the second coke particles have a particle size greater than 105 μm.

[0177] A method of C6.C5, wherein the first coke particle collection is substantially free of second coke particles having a particle size greater than 105 μm.

[0178] A method of C7.C1 to C5, wherein the first coke particle collection further contains coke particles having a particle size greater than 105 μm.

[0179] A method of C8.C1 to C7, further comprising mixing the first coke particle collection, the carrier fluid and optionally the second proppant particle collection with at least one additive.

[0180] A method of C9.C8, wherein the additive comprises at least one of the following substances: acids, biocides, breaker agents, corrosion inhibitors, cross - linkers, friction reducers, gels, de - oxygenating agents, pH control additives, scale inhibitors, surfactants, weighting agents, inert solids, fluid loss control agents, emulsifiers, emulsion diluents, emulsion thickeners, viscosifiers, foaming agents, stabilizers, chelating agents, mutual solvents, oxidizing agents, reducing agents and clay stabilizers.

[0181] A method of C10.C1 to C9, wherein the micro - proppant coke particles contain petroleum coke fines, and wherein the first coke particle collection contains petroleum coke particles.

[0182] A method of C11.C10, wherein the micro - proppant coke particles contain at least one of wet flexible coke fines and dry flexible coke fines.

[0183] A method of C12.C11, wherein the method further comprises via FLEXICOKING TMThe process produces at least one of wet flexible coke fines and dry flexible coke fines.

[0184] A method according to any one of C13.C1 to C12, wherein the micro - proppant coke particles comprise at least one of the following: screened fluid coke, screened flexible coke, screened delayed coke, screened heat - treated coke, screened pyrolysis coke, and screened coal - derived coke.

[0185] A method according to C14.C13, wherein the method further comprises screening at least one of fluid coke, flexible coke, delayed coke, heat - treated coke, pyrolysis coke, and coal - derived coke to provide micro - proppant coke particles having a particle size of at most 105 μm.

[0186] A method according to any one of C15.C1 to C14, wherein the micro - proppant coke particles comprise at least one of the following: ground fluid coke, ground flexible coke, ground delayed coke, ground heat - treated coke, ground pyrolysis coke, and ground coal - derived coke.

[0187] A method according to C16.C15, wherein the method further comprises grinding at least one of fluid coke, flexible coke, delayed coke, heat - treated coke, pyrolysis coke, and coal - derived coke to provide micro - proppant coke particles having a particle size of at most 105 μm.

[0188] A method according to any one of C17.C1 to C16, wherein the carrier fluid comprises water.

[0189] A method according to any one of C18.C1 to C16, wherein the carrier fluid is substantially free of water.

[0190] A method according to any one of C19.C1 to C18, wherein the carrier fluid comprises at least one of liquid CO2 and supercritical CO2.

[0191] While the aspects and embodiments described herein are well calculated to achieve the advantages set forth, it should be understood that these aspects and embodiments are susceptible to modification, variation, and change without departing from their spirit. In other words, the specific aspects and embodiments described herein are illustrative only, as the teachings of the technology can be practiced in different but equivalent ways that will be apparent to those skilled in the art who benefit from the teachings herein. Additionally, the systems and methods illustratively disclosed herein can be practiced appropriately without any element and / or any optional element not specifically disclosed herein. While compositions and methods are described in terms of "comprising" or "including" various components or steps, the compositions and methods can also "consist essentially of" or "consist of" the various components and steps. Indeed, the technology of the present invention encompasses all alternatives, improvements, and equivalents that fall within the true spirit and scope of the appended claims.

Claims

1. A fracturing fluid comprising a carrier fluid and coke particles, wherein: the coke particles comprise micro - proppant coke particles having a particle size of at most 105 micrometers (μm); the micro - proppant coke particles have a total concentration of at least 3 weight percent (wt%), based on the total weight of the coke particles in the fracturing fluid; and the coke particles have a total concentration in the fracturing fluid of 14 kg / m³ to 480 kg / m³, based on the volume of the carrier fluid.

2. The fracturing fluid of claim 1, wherein the coke particles have a total concentration of 18 kg / m³ to 120 kg / m³, based on the volume of the carrier fluid.

3. The fracturing fluid of claim 1, wherein the coke particles have a total concentration of 23 kg / m³ to 96 kg / m³, based on the volume of the carrier fluid.

4. The fracturing fluid of claim 1, wherein the micro - proppant coke particles have a total concentration of 5 wt% to 100 wt%, based on the total weight of the coke particles in the fracturing fluid.

5. The fracturing fluid of claim 1, wherein the micro - proppant coke particles have a total concentration of 30 wt% to 80 wt%, based on the total weight of the coke particles in the fracturing fluid.

6. The fracturing fluid of claim 1, wherein the micro - proppant coke particles comprise petroleum coke fines, and wherein the coke particles comprise petroleum coke particles.

7. The fracturing fluid of claim 4, wherein the micro - proppant coke particles comprise at least one of wet flexible coke fines and dry flexible coke fines.

8. The fracturing fluid of claim 7, wherein the wet flexible coke fines have a median particle size of 8 μm to 22 μm.

9. The fracturing fluid of claim 7, wherein the dry flexible coke fines have a median particle size of 6 μm to 16 μm.

10. The fracturing fluid of claim 1, wherein the micro - proppant coke particles comprise fluid coke particles.

11. The fracturing fluid of claim 1, wherein the micro - proppant coke particles comprise at least one of: screened fluid coke, screened flexible coke, screened delayed coke, screened heat - treated coke, screened pyrolysis coke, and screened coal - derived coke.

12. The fracturing fluid of claim 11, wherein at least one of the screened fluid coke, screened flexible coke, screened delayed coke, screened heat - treated coke, screened pyrolysis coke, and screened coal - derived coke has a median particle size of 76 μm to 86 μm.

13. The fracturing fluid of claim 1, wherein the micro - proppant coke particles comprise at least one of: ground fluid coke, ground flexible coke, ground delayed coke, ground heat - treated coke, ground pyrolysis coke, and ground coal - derived coke.

14. The fracturing fluid of claim 1, wherein the coke particles further comprise a second portion having a particle size greater than 105 μm.

15. The fracturing fluid of claim 1, further comprising a third proppant particle different from the coke particles.

16. The fracturing fluid of claim 15, wherein the third proppant particle comprises sand.

17. The fracturing fluid of claim 15, wherein the third proppant particles comprise at least one of lightweight proppant (LWP) and ultra-lightweight proppant (ULWP).

18. The fracturing fluid of claim 1, wherein the carrier fluid comprises water.

19. The fracturing fluid of claim 1, wherein the carrier fluid is substantially free of water.

20. The fracturing fluid of claim 1, wherein the carrier fluid comprises at least one of liquid carbon dioxide (CO2) and supercritical CO2.

21. The fracturing fluid of claim 1, further comprising at least one of the following substances: acid, biocide, breaker, corrosion inhibitor, crosslinking agent, friction reducer, gel, deoxidizer, pH control additive, scale inhibitor, surfactant, weighting agent, inert solid, filtration control agent, emulsifier, emulsion diluent, emulsion thickener, viscosifier, foaming agent, stabilizer, chelating agent, mutual solvent, oxidizing agent, reducing agent, and clay stabilizer.

22. A method, comprising: (I) introducing a fracturing fluid into a subterranean formation, the fracturing fluid comprising a carrier fluid and coke particles, wherein the coke particles comprise microproppant coke particles having a particle size of at most 105 micrometers (μm) at a concentration of at least 3 weight percent (wt%), based on the total weight of the coke particles in the fracturing fluid, and wherein the coke particles have a total concentration in the fracturing fluid of 14 kilograms per cubic meter to 240 kilograms per cubic meter, based on the volume of the carrier fluid.

23. The fracturing fluid of claim 22, wherein the coke particles have a total concentration of 18 kilograms per cubic meter to 120 kilograms per cubic meter, based on the volume of the carrier fluid.

24. The fracturing fluid of claim 22, wherein the coke particles have a total concentration of 23 kilograms per cubic meter to 96 kilograms per cubic meter, based on the volume of the carrier fluid.

25. The method of claim 22, wherein the microproppant coke particles have a total concentration of 5 wt% to 100 wt%, based on the total weight of the coke particles in the fracturing fluid.

26. The method of claim 22, wherein the microproppant coke particles have a total concentration of 30 wt% to 80 wt%, based on the total weight of the coke particles in the fracturing fluid.

27. The method of claim 22, wherein the microproppant coke particles comprise petroleum coke fines, and wherein the coke particles comprise petroleum coke particles.

28. The method of claim 27, wherein the microproppant coke particles comprise at least one of wet flexible coke fines and dry flexible coke fines.

29. The method of claim 28, wherein the method further comprises producing at least one of wet flexicoke fines and dry flexicoke fines via a FLEXICOKING TM process.

30. The method of claim 28, wherein the wet flexible coke fines have a median particle size of 8 μm to 22 μm.

31. The method of claim 28, wherein the dry flexible coke fines have a median particle size of 6 μm to 16 μm.

32. The method of claim 27, wherein the microproppant coke particles comprise fluid coke particles.

33. The method of claim 22, wherein the micro - proppant coke particles have an apparent density of 1.0 grams per cubic centimeter (g / cm 3 ) to 2.0 g / cm 3 .

34. The method of claim 22, wherein the micro - proppant coke particles comprise at least one of the following: screened fluid coke, screened flexible coke, screened delayed coke, screened heat - treated coke, screened pyrolysis coke, and screened coal - derived coke.

35. The method of claim 34, wherein at least one of the screened fluid coke, screened flexible coke, screened delayed coke, screened heat - treated coke, screened pyrolysis coke, and screened coal - derived coke has a median particle size of 76 μm to 86 μm.

36. The method of claim 34, wherein the method further comprises screening at least one of fluid coke, flexible coke, delayed coke, heat - treated coke, pyrolysis coke, and coal - derived coke to obtain micro - proppant coke particles having a particle size of at most 105 μm.

37. The method of claim 22, wherein the micro - proppant coke particles comprise at least one of the following: ground fluid coke, ground flexible coke, ground delayed coke, ground heat - treated coke, ground pyrolysis coke, and ground coal - derived coke.

38. The method of claim 37, wherein the method further comprises grinding at least one of fluid coke, flexible coke, delayed coke, heat - treated coke, pyrolysis coke, and coal - derived coke to obtain micro - proppant coke particles having a particle size of at most 105 μm.

39. The method of claim 22, comprising introducing the fracturing fluid into a subterranean formation during the pad phase of a hydraulic fracturing operation, and then introducing a second fracturing fluid comprising a carrier fluid and at least one of the following into the subterranean formation: (i) second proppant particles comprising second coke particles but substantially free of the micro - proppant coke particles; and (ii) third proppant particles substantially free of coke particles.

40. The method of claim 22, wherein the coke particles further comprise a second portion having a particle size greater than 105 μm.

41. The method of claim 22, wherein step (I) is performed during the pad phase of a hydraulic fracturing operation.

42. The method of claim 41, wherein the hydraulic fracturing fluid is substantially free of proppant particles having a particle size greater than 105 μm.

43. The method of claim 41, wherein the fracturing fluid comprises the micro - proppant coke particles at a concentration of at least 80 wt%, based on the total weight of all micro - proppant particles present in the fracturing fluid.

44. The method of claim 22, wherein the fracturing fluid further comprises third proppant particles different from the coke particles.

45. The method of claim 44, wherein the third proppant particles comprise sand.

46. The method of claim 44, wherein the third proppant particles comprise at least one of light - weight proppant (LWP) and ultra - light - weight proppant (ULWP).

47. The method of claim 22, wherein step (I) is performed at least during the slurry phase of a hydraulic fracturing operation.

48. The method of claim 47, wherein the hydraulic fracturing fluid further comprises second coke particles having a particle size greater than 105 μm.

49. The method of claim 44, wherein the fracturing fluid comprises the micro - proppant coke particles at a concentration of at most 10 wt%, based on the total weight of all coke particles present in the fracturing fluid.

50. The method of claim 22, comprising a first interval and a second interval, wherein: During the first interval, the micro - proppant coke particles have a total concentration of at least 50 wt%, based on the total weight of the coke particles in the fracturing fluid; and During the second interval, the micro - proppant coke particles have a total concentration of at most 20 wt%, based on the total weight of the coke particles in the fracturing fluid.

51. The method of claim 22, comprising a first interval and a second interval, wherein: During the first interval, step (I) is carried out, wherein the micro - proppant coke particles have a total concentration of at least 50 wt%, based on the total weight of the coke particles in the fracturing fluid; and During the second interval, the following steps are carried out: Introduce a second fracturing fluid comprising a carrier fluid and second coke particles, wherein the second coke particles comprise micro - proppant coke particles at a total concentration of less than 3 wt%, based on the total weight of the second coke particles in the second fracturing fluid.

52. A method for preparing a fracturing fluid, comprising: Providing a first collection of coke particles comprising micro - proppant coke particles, wherein the micro - proppant coke particles have a particle size of at most 105 micrometers (μm); and Mixing the first collection of coke particles with a carrier fluid and optionally a second collection of proppant particles, wherein the total concentration of the micro - proppant coke particles is at least 3 weight percent (wt%), based on the total weight of the coke particles comprised in the first collection of coke particles and the second collection of proppant particles; and wherein the mass of the coke particles is from 14 kilograms per cubic meter to 240 kilograms per cubic meter relative to the volume of the carrier fluid.

53. The method of claim 52, wherein the mass of the coke particles is from 18 kilograms per cubic meter to 120 kilograms per cubic meter relative to the volume of the carrier fluid.

54. The method of claim 52, wherein the mass of the coke particles is from 23 kilograms per cubic meter to 96 kilograms per cubic meter relative to the volume of the carrier fluid.

55. The method of claim 52, wherein the particle size of the micro - proppant coke particles is at most 88 μm.

56. The method of claim 52, wherein the second collection of proppant particles comprises at least one of non - coke particles and second coke particles different from the coke particles within the first collection of coke particles.

57. The method of claim 56, wherein the non - coke particles comprise at least one of sand, light weight proppant (LWP), and ultra - light weight proppant (ULWP).

58. The method of claim 56, wherein the second coke particles have a particle size greater than 105 μm.

59. The method of claim 58, wherein the first collection of coke particles is substantially free of second coke particles having a particle size greater than 105 μm.

60. The method of claim 52, wherein the first collection of coke particles further comprises coke particles having a particle size greater than 105 μm. The method of claim 52, further comprising mixing the first coke particle collection, the carrier fluid, and optionally the second proppant particle collection with at least one additive. The method of claim 52, wherein the micro - proppant coke particles comprise petroleum coke fines, and wherein the first coke particle collection comprises petroleum coke particles. The method of claim 62, wherein the micro - proppant coke particles comprise at least one of wet flexible coke fines and dry flexible coke fines.

64. The method of claim 63, wherein the method further comprises producing at least one of wet flexicoke fines and dry flexicoke fines via a FLEXICOKING TM process. The method of claim 52, wherein the micro - proppant coke particles comprise at least one of the following: screened fluid coke, screened flexible coke, screened delayed coke, screened heat - treated coke, screened pyrolysis coke, and screened coal - derived coke. The method of claim 65, wherein the method further comprises screening at least one of fluid coke, flexible coke, delayed coke, heat - treated coke, pyrolysis coke, and coal - derived coke to provide micro - proppant coke particles having a particle size of at most 105 μm. The method of claim 52, wherein the micro - proppant coke particles comprise at least one of the following: ground fluid coke, ground flexible coke, ground delayed coke, ground heat - treated coke, ground pyrolysis coke, and ground coal - derived coke. The method of claim 67, wherein the method further comprises grinding at least one of fluid coke, flexible coke, delayed coke, heat - treated coke, pyrolysis coke, and coal - derived coke to provide micro - proppant coke particles having a particle size of at most 105 μm.

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