Drilling Fluid

Abstract

The present application discloses a drilling fluid composition, which is suitable for use in drilling wells in underground rock formations and other oil and gas operations. The drilling fluid composition of the present application comprises a condensation product of a trifunctional amine and a fatty acid and an oil-based fluid. The present application also describes a method for preparing the drilling fluid composition.

Description

[0001] Cross-references

[0002] This application is related to and claims priority to U.S. Provisional Patent Application No. 63 / 113,417 filed on November 13, 2020, which is incorporated herein by reference.

[0003] field

[0004] The present invention generally relates to drilling fluid compositions, for example, for drilling wells in underground rock formations, and to methods for preparing the same. Specifically, the drilling fluid compositions described herein contain condensation products of trifunctional amines and fatty acids, and provide emulsified drilling muds with improved rheological properties and stability.

[0005] background

[0006] In various oil and gas operations, drilling fluid (also known as drilling mud) is generally used to assist in drilling holes (e.g., wellbores) in the earth. For example, drilling fluid is generally used to drill for oil and / or natural gas and for production drilling. When used, the drilling fluid is generally pumped from the surface to the wellbore together with various additives, such as coolants and stabilizers. In this way, the drilling fluid carries the wellbore cuttings to the surface, cools and lubricates the components of the drill pipe (e.g., the drill bit), and provides hydrostatic pressure so that fluids from the rock formations do not enter the wellbore. When drilling stops, the drilling fluid can also be used to suspend the cuttings in the drilling mud. In addition, the drilling fluid can be introduced into the operation of various downhole tools, such as mud pulse telemetry for transmitting signals via the wellbore.

[0007] It is generally recognized that drilling fluids are critical to successful drilling operations, and improvements in drilling fluids contribute to improvements in drilling operations. Due to improvements in drilling technology, it is now possible to drill deeper, longer, and more challenging wells, such as using more effective drilling fluids. Typically, the drilling fluid used in a given drilling operation is selected based on the operation in which the drilling fluid is used, the wellbore conditions, and the ability to limit corrosion and damage to the formation.

[0008] Drilling fluids can be classified in a variety of ways, but generally refer to the composition of the drilling fluid. For example, drilling fluids can be defined as "water-based muds" or "oil-based muds." The different compositions are generally associated with differences in performance characteristics. For example, water-based muds generally do not flow freely when pumped and gel when idle, thereby suspending drill cuttings and resisting pumping. Oil-based muds contain organic base fluids, such as petroleum products (e.g., diesel fuel). For these oil-based fluid systems, oil-based muds generally show increased lubricity and reduced viscosity. In addition, oil-based muds can generally withstand greater heat and will not degrade. Moreover, oil-based muds can be used in formations containing water-sensitive clay materials.

[0009] Regardless of how it is classified, drilling fluids typically contain a dispersion of oil and water in combination with various additives to maintain dispersion. For example, emulsifiers, wetting agents, and gelling agents can be used to control the stability, viscosity, cooling, and lubrication of oil-based drilling fluid systems. In particular, emulsifiers are included to promote the stability of drilling fluids, especially oil-based muds. The stability of oil-based drilling muds typically involves preventing the fluid from separating into two layers, i.e., an aquifer and an organic layer. Without a suitable emulsifier, oil-based muds may phase separate and require vigorous mixing before they can be used in drilling operations.

[0010] There remains a need for drilling fluids for use in drilling operations that are sufficiently stable and exhibit suitable performance characteristics (eg, rheological properties).

[0011] Overview

[0012] The present invention relates to a drilling fluid composition comprising: 0.1 wt% to 10 wt% of a condensation product of a trifunctional amine and a fatty acid, wherein the trifunctional amine may contain 6-12 carbon atoms, the fatty acid may contain palmitic acid, oleic acid, linoleic acid, abietic acid, (Z)-6-hexadecenoic acid, palmitoleic acid, myristic acid, elaidic acid, 11-octadecenoic acid or tall oil, isomers thereof, or a combination thereof, such as a compound having formula 1 or 2a or 2b, wherein the weight ratio between the trifunctional amine and the fatty acid in the condensation product is in the range of 0.1:1 to 10:1, such as 0.3:1 to 2:1; and an oil-based fluid, which may be diesel, mineral oil, a linear olefin or a linear alkane or a combination thereof. The drilling fluid composition may exhibit a plastic viscosity at 25°C greater than 15 cP and / or a plastic viscosity at 80°C greater than 10 cP, and / or a yield point at 25°C greater than 15 lb / 100 ft 2 , and / or a yield point greater than 10 lb / 100 ft at 80°C 2 , and / or the ratio between the yield point and the plastic viscosity is less than 2. The drilling fluid composition may further comprise a viscosity improver, a pH improver, a density improver, a filtration improver, an aqueous component, a shale inhibitor, or a combination thereof. The trifunctional amine may have a chemical formula C x H y (NH2)3, wherein x is 6-12; and wherein y is less than or equal to 23.

[0013] The present invention also relates to a method for preparing a drilling fluid composition, comprising: reacting a trifunctional amine with a fatty acid at a temperature of at least 100° C. for at least 10 hours to form a condensation product; and adding the condensation product to an oil-based fluid to form a drilling fluid composition; wherein the condensation product contains less than 15% by weight of impurities.

[0014] The method may further include the step of adding a viscosity improver, a pH improver, a density improver, a filter improver, an aqueous component, a shale inhibitor, or a combination thereof to the oil-based fluid. The oil-based fluid, the trifunctional amine, and the fatty acid may be as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be described in detail below with reference to the accompanying drawings, wherein like symbols represent like components.

[0017] Figure 1 The present invention shows (a) a condensation product, (b) a fatty acid reagent and (c) a trifunctional amine. 1 HNMR spectrum.

[0018] Details

[0019] Introduction

[0020] As mentioned above, conventional drilling fluids, particularly oil-based muds, contain a dispersion of oil and water. To be used in drilling operations, the drilling fluid must be sufficiently stable to prevent phase separation, such as separation into an aqueous (water) layer and an organic (oil) layer. The stability of the drilling fluid can be improved by adding emulsifiers, such as polyaminated fatty acids, aliphatic amines, and organic polymers. However, these conventional emulsifiers have performance problems, especially at high temperatures.

[0021] The inventors have found that the condensation reaction of trifunctional amines with fatty acids yields condensation products with excellent emulsifying properties. For example, the condensation product can ensure the stability of the synthetic emulsion for several hours (e.g., at least 2 hours, at least 4 hours, at least 10 hours, or at least 24 hours). Importantly, the inventors have found that in some embodiments, the weight ratio between the trifunctional amine and the fatty acid can contribute to the emulsifying properties of the condensation product.

[0022] Advantageously, the condensation products of the present invention can be prepared using a preparation method that does not require a complex synthetic route, which contributes to the ease and efficiency of the entire process. Moreover, the preparation method no longer requires the use of environmentally friendly reactants, which provides additional process and safety benefits.

[0023] Thus, the present invention relates to a drilling fluid composition comprising the condensation product described herein as an emulsifier. In particular, some embodiments of the present invention relate to a drilling fluid composition comprising 0.1 wt % to 10 wt % of a condensation product of a trifunctional amine and a fatty acid, wherein the weight ratio between the trifunctional amine and the fatty acid in the condensation product is in the range of 0.1:1 to 10:1; and an oil-based fluid. In addition, some embodiments of the present invention relate to a method for preparing such a drilling fluid composition. As described below, the drilling fluid composition advantageously exhibits improved stability as well as improved plastic viscosity and yield point.

[0024] Trifunctional amine

[0025] The condensation product of the present invention is formed by reacting a trifunctional amine with a fatty acid. The trifunctional amine comprises an organic compound having at least three amino functional groups, for example, three amino functional groups, four amino functional groups, five amino functional groups, six amino functional groups or seven amino functional groups. In some embodiments of the drilling fluid composition, the trifunctional amine comprises a combination of two or more of the compounds.

[0026] The individual amino functional groups of the trifunctional amine can be subdivided into primary (or 1°) amines, secondary (or 2°) amines, or tertiary (or 3°) amines. In some embodiments, the amino groups of the trifunctional amine can belong to different subclasses. For example, in some embodiments, the trifunctional amine can have primary amino functional groups, secondary amino functional groups, and tertiary amino functional groups. The trifunctional amino group has at least one primary amino functional group, such as at least two primary amino functional groups or at least three primary amino functional groups. Unlike the amines used in conventional drilling fluids, such as DETA, in some embodiments, all of the amino functional groups of the trifunctional amine are primary amino groups.

[0027] As an organic compound, the trifunctional amine in the present invention must include at least one carbon atom. In some embodiments, the trifunctional amine includes 6-12 carbon atoms, such as 6-11 carbon atoms, 6-10 carbon atoms, 7-12 carbon atoms, 7-11 carbon atoms, 7-10 carbon atoms, 8-12 carbon atoms, 8-11 carbon atoms, 8-10 carbon atoms, 9-12 carbon atoms, 9-11 carbon atoms, or 9-10 carbon atoms. With regard to the lower limit, the trifunctional amine can include at least 6 carbon atoms, such as at least 7 carbon atoms, at least 8 carbon atoms, or at least 9 carbon atoms. With regard to the upper limit, the trifunctional amine can include less than 12 carbon atoms, such as less than 11 carbon atoms, or less than 10 carbon atoms.

[0028] There are no particular restrictions on the organic structure of the trifunctional amine. In some embodiments, the trifunctional amine can be saturated. In other embodiments, the trifunctional amine can be unsaturated, such as alkene or alkyne as the base hydrocarbon (base aliphatic chain). In some embodiments, the trifunctional amine can be monounsaturated or polyunsaturated, such as cumulative diene, conjugated diene or non-conjugated diene. In some embodiments, the trifunctional amine can include open-chain compounds, linear compounds, branched compounds, cyclic compounds or combinations thereof.

[0029] In some embodiments, the trifunctional amines of the present invention may have the following chemical formula:

[0030] C x H y (NR′R″)3.

[0031] In one embodiment, x in the above formula is 6-12, such as 6-11, 6-10, 7-12, 7-11, 7-10, 8-12, 8-11, 8-10, 9-12, 9-11, or 9-10. In terms of lower limits, x can be at least 6, such as at least 7, at least 8, or at least 9. In terms of upper limits, x can be less than 12, such as less than 11, or less than 10.

[0032] In one embodiment, y in the above chemical formula is 3-23, such as 4-23, 5-23, 6-23, 3-22, 4-22, 5-22, 6-22, 3-21, 4-21, 5-21, 6-21, 3-20, 4-20, 5-20, 6-20, 3-23, 4-23, 5-23, 6-23, 3-18, 4-18, 5-18, or 6-18. In terms of upper limits, y can be 23 or less, such as 22 or less, 21 or less, 20 or less, 19 or less, or 18 or less. In terms of lower limits, y can be at least 3, such as at least 4, at least 5, or at least 6.

[0033] In the above chemical formula, R′ and R″ can each be hydrogen or an alkyl group having 1-6 carbon atoms. In some embodiments, R′ and R″ have different structures. For example, in some embodiments, R′ is hydrogen, and R″ is an alkyl group having less than 6 carbon atoms, such as having less than 5 carbon atoms, less than 4 carbon atoms, or less than 3 carbon atoms. In some embodiments, R′ and R″ have the same structure. In some embodiments, for example, R′ and R″ are both hydrogen.

[0034] Examples of suitable trifunctional amines include, but are not limited to, triaminohexane, triaminoheptane, triaminooctane, triaminononane, triaminodecane, triaminoundecane, triaminododecane, triaminocyclohexane, triaminocycloheptane, triaminocyclooctane, triaminocyclononane, triaminocyclodecane, triaminocycloundecane, triaminocyclododecane, triaminohexene, triaminoheptene, triaminooctene, triaminononene, triaminodecene, triaminoundecene, triamino ... dicarbene, tetraaminohexane, tetraaminoheptane, tetraaminooctane, tetraaminononane, tetraaminodecane, tetraaminoundecane, tetraaminododecane, tetraaminocyclohexane, tetraaminocycloheptane, tetraaminocyclooctane, tetraaminocyclononane, tetraaminocyclodecane, tetraaminocycloundecane, tetraaminocyclododecane, tetraaminohexene, tetraaminoheptene, tetraaminooctene, tetraaminononene, tetraaminodecene, tetraaminoundecene, tetraaminododecene, or isomers thereof, or combinations thereof.

[0035] An example of a commercially available trifunctional amine suitable for use in drilling fluid compositions is Hexatran from Ascend Performance Materials. TM .

[0036] fatty acid

[0037] The condensation reaction also uses fatty acids as reactants. Fatty acids include organic compounds having both a carboxylic acid functional group (COOH) and an aliphatic chain. In some embodiments of the drilling fluid composition, the fatty acid includes a combination of two or more of the compounds.

[0038] There are no particular limitations on the fatty acids in the drilling fluid composition. In one embodiment, the fatty acids contain 8-24 carbon atoms, such as 9-24 carbon atoms, 10-24 carbon atoms, 11-24 carbon atoms, 12-24 carbon atoms, 13-24 carbon atoms, 14-24 carbon atoms, 8-23 carbon atoms, 9-23 carbon atoms, 10-23 carbon atoms, 11-23 carbon atoms, 12-23 carbon atoms, 13-23 carbon atoms, 14-23 carbon atoms, 8-22 carbon atoms, 9-22 carbon atoms, 10-22 carbon atoms. In some embodiments, the fatty acid may contain more than 8 carbon atoms, such as more than 9 carbon atoms, more than 10 carbon atoms, more than 11 carbon atoms, more than 12 carbon atoms, more than 13 carbon atoms, or more than 14 carbon atoms. In terms of upper limits, the fatty acid can contain less than 24 carbon atoms, eg, less than 23 carbon atoms, less than 22 carbon atoms, less than 21 carbon atoms, or less than 20 carbon atoms.

[0039] There are no particular restrictions on the organic structure of lipid acid. In some embodiments, the aliphatic chain of lipid acid can be saturated. In other embodiments, the aliphatic chain of lipid acid can be undersaturated. In some embodiments, lipid acid can be monounsaturated or polyunsaturated, for example cumulative diene, conjugated diene or non-conjugated diene. In some embodiments, lipid acid can comprise open-chain compound, straight-chain compound, branched-chain compound, cyclic compound or their combination.

[0040] In other words, in some embodiments, the fatty acids of the present invention have the following formula:

[0041] C a H b COOH.

[0042] In one embodiment, a in the above formula is 8-24, such as 9-24, 10-24, 11-24, 12-24, 13-24, 14-24, 8-23, 9-23, 10-23, 11-23, 12-23, 13-23, 14-23, 12-20, 14-20, 14-18, 15-18, 8-22, 9-22, 10-22, 11-22, 12-22, 13-22, 14-22, 8-21, 9-21, 10-21, 11-21, 12-21, 13-21, 14-21, 8-20, 9-20, 10-20, 11-20, 12-20, 13-20, or 14-20. In terms of lower limits, a may be greater than 8, such as greater than 9, greater than 10, greater than 11, greater than 12, greater than 13, or greater than 14. In terms of upper limits, a may be less than 24, such as less than 23, less than 22, less than 21, or less than 20.

[0043] In one embodiment, b in the above formula is 7-49, e.g., 9-49, 11-49, 13-47, 15-47, 7-47, 9-47, 11-47, 13-47, 15-47, 7-45, 9-45, 11-45, 13-45, 15-45, 7-43, 9-43, 11-43, 13-43, 15-43, 7-41, 9-41, 11-41, 13-41, 15-41, 7-39, 9-39, 11-39, 13-39, 15-39, 7-37, 9-37, 11-37, 13-37, or 15-37. In terms of upper limits, b may be 49 or less, such as 47 or less, 45 or less, 43 or less, 41 or less, 39 or less, or 37 or less. In terms of lower limits, y may be at least 7, such as at least 9, at least 11, at least 13, or at least 15.

[0044] There is no particular limitation on the fatty acid in the drilling fluid composition, and any fatty acid that meets the above conditions can be used in the present invention. Examples of suitable fatty acids include, but are not limited to, palmitic acid, oleic acid, linoleic acid, conjugated linoleic acid, abietic acid, stearic acid, linolenic acid, hexadecatetraenoic acid, nonadecanoic acid, eicosanoic acid, heneicosanoic acid, (Z)-6-hexadecenoic acid, palmitoleic acid, myristic acid, elaidic acid, 11-octadecenoic acid, isomers thereof, and combinations thereof.

[0045] As described above, in some embodiments of the drilling fluid composition, the fatty acid comprises a mixture of fatty acids. In some embodiments, for example, the fatty acid may comprise a mixture of palmitic acid, oleic acid, and linoleic acid.

[0046] In some embodiments, the fatty acid in the drilling fluid composition may include a mixture of fatty acids from tall oil. Tall oil, also known as liquid rosin, generally refers to a byproduct obtained from the Kraft process for producing wood pulp. The composition of tall oil varies depending on the type of wood used in production. The typical composition of tall oil includes rosin, resin acids, fatty acids, fatty alcohols and sterols. By fractionation, the rosin content of tall oil can be reduced to obtain tall oil fatty acids. Tall oil fatty acids generally include a mixture of fatty acids, including a mixture of oleic acid and rosin acid. The fatty acid in the drilling fluid composition may include tall oil fatty acids.

[0047] An example of a commercially available tall oil fatty acid suitable for use in drilling fluid compositions is SYLFAT from Kraton Corp. TM FA1.

[0048] Condensation product

[0049] As described above, the drilling fluid composition comprises a condensation product formed from the above-mentioned trifunctional amine and a fatty acid. In some embodiments, the condensation product is an amide formed by a condensation reaction between the primary amine group of the trifunctional amine and the acid group of the fatty acid. In some cases, the condensation product can have a structure of a trifunctional amine backbone and a fatty acid substituent.

[0050] In some cases, the condensation product is obtained from a chemical transfer reaction involving a trifunctional amine and a fatty acid. In some cases, the condensation product may correspond to Formula 1 below.

[0051]

[0052] R1 can be an alkyl, alkenyl or alkynyl group (optionally having 8-24 carbon atoms, such as 9-24, 10-20, 12-20, 14-20, 12-18 or 15-18 carbon atoms, and other carbon number ranges of fatty acid moieties disclosed herein are also contemplated for use in Formula 1). R1 ​​can be a group derived from a reactant fatty acid.

[0053] R2 may be an alkyl, alkenyl or alkynyl group (optionally having 1-10 carbon atoms, such as 1-8, 1-6, 1-5 or 1-4 carbon atoms).

[0054] R3 may be an alkyl, alkenyl or alkynyl group (optionally having 1-10 carbon atoms, such as 1-8, 1-6, 1-5 or 1-4 carbon atoms).

[0055] R4 can be amino (substituted or unsubstituted), for example alkylamino, alkenylamino or alkynylamino (optionally having 1-10 carbon atoms, for example 1-8, 1-6, 1-5 or 1-4 carbon atoms), and y can be 0 or an integer. Amino can include, for example, alkylamino, alkenylamino and alkynylamino. In some cases, R4 is amino, for example NH. In other cases, R4 is alkylamino, for example HN-alkyl. Amino-oxy-alkyl, for example O-NH-alkyl, can also be considered.

[0056] As non-limiting examples, in the embodiment where the trifunctional amine comprises triaminononane and the fatty acid comprises oleic acid, the condensation product can comprise a compound with the following structural formula 2a and / or 2b. Of course, as described above, other fatty acid substituents can also be considered. And the scope of the present invention is not limited to the acid structure part of palmitic acid or oleic acid as the condensation product.

[0057]

[0058] The present inventors have discovered that the stability and rheological properties of the drilling fluid composition can be affected by the weight ratio between the trifunctional amine and the fatty acid in the condensation product. In particular, the present inventors have surprisingly discovered that the stability can be advantageously improved by preparing the condensation product according to a specific weight ratio between the trifunctional amine and the fatty acid. In one embodiment, the weight ratio between the trifunctional amine and the fatty acid is in the range of 0.1:1 to 10:1, for example 0.2:1 to 10:1, 0.3:1 to 10:1, 0.4:1 to 10:1, 0.5:1 to 10:1, 0.1:1 to 8:1, 0.2:1 to 8:1, 0.3:1 to 8:1, 0.4:1 to 8:1, 0.5:1 to 8:1, 0.1:1 to 6:1, 0.2:1 to 6:1, 0.3:1 to 6:1, 0.4:1 to 6:1. : 1, 0.5: 1 to 6: 1, 0.1: 1 to 4: 1, 0.2: 1 to 4: 1, 0.3: 1 to 4: 1, 0.4: 1 to 4: 1, 0.5: 1 to 4: 1, 0.1: 1 to 2: 1, 0.2: 1 to 2: 1, 0.3: 1 to 2: 1, 0.4: 1 to 2: 1, 0.5: 1 to 2: 1, 0.1: 1 to 1.5: 1, 0.2: 1 to 1.5: 1, 0.3: 1 to 1.5: 1, 0.4: 1 to 1.5: 1, or 0.5: 1 to 1.5: 1. In terms of lower limits, the weight ratio between the trifunctional amine and the fatty acid can be greater than 0.1: 1, for example, greater than 0.2: 1, greater than 0.3: 1, greater than 0.4: 1, or greater than 0.5: 1. In terms of upper limits, the weight ratio between the trifunctional amine and the fatty acid can be less than 10:1, eg, less than 8:1, less than 6:1, less than 4:1, less than 2:1, or less than 1.5:1.

[0059] In some embodiments, the drilling fluid composition comprises 0.1 wt % to 35 wt % of the condensation product, such as 0.1 wt % to 25 wt %, 0.1 wt % to 10 wt %, 0.5 wt % to 10 wt %, 0.5 wt % to 7 wt %, 0.7 wt % to 7 wt %, 1 wt % to 5 wt %, or 1 wt % to 4 wt %. In terms of lower limits, the drilling fluid composition may comprise more than 0.1 wt % of the condensation product, such as more than 0.3 wt %, more than 0.5 wt %, more than 0.7 wt %, more than 1 wt %, more than 2 wt %, more than 3 wt %, more than 5 wt %, more than 7 wt %, or more than 10 wt %. In terms of upper limits, the drilling fluid composition may comprise less than 35 wt % of the condensation product, such as less than 25 wt %, less than 20 wt %, less than 15 wt %, less than 12 wt %, less than 10 wt %, less than 7 wt %, less than 5 wt %, less than 4 wt %, or less than 3 wt %.

[0060] Base fluid

[0061] As mentioned above, drilling fluids are often classified according to the type of base fluid they contain. For example, drilling fluids with an aqueous base fluid are often referred to as "water-based muds," while drilling fluids with an organic base fluid are often referred to as "oil-based muds." The condensation products described herein may be suitable as emulsifiers for use in a variety of drilling fluids, including, for example, water-based muds and oil-based muds.

[0062] In some embodiments, the drilling fluid composition of the present invention comprises an oil-based fluid. In other words, the drilling fluid composition of the present invention can be an oil-based mud. Traditional oil-based drilling fluid systems were first developed in the 1960s and used to help solve some drilling problems associated with water-based muds, including clay swelling, high temperature degradation, the presence of contaminants, and poor lubricity. Oil-based muds and the drilling fluid compositions described herein are less affected by these problems.

[0063] There is no particular restriction on the composition of the oil-based fluid. For example, in some cases, the oil-based fluid may include diesel, mineral oil, straight-chain olefins, straight-chain alkanes or a combination thereof. Suitable examples of diesel include diesel from petroleum sources, synthetic diesel and / or biodiesel. Suitable examples of mineral oil include paraffin oil, cycloparaffin oil and / or aromatic oil.

[0064] In addition to the oil-based fluid, the drilling fluid composition may also include an aqueous component, such as water (e.g., deionized water) or brine. The aqueous phase may be a dispersed phase in the oil-based fluid. In other words, the drilling fluid composition may include an emulsion in which the aqueous phase is dispersed in the oil-based fluid. As described in detail below, the condensation product is used in the drilling fluid composition as an emulsifier to improve the stability of the emulsion.

[0065] In the liquid phase of an oil-based system, the ratio between the percentage of oil and the percentage of water is generally referred to as the oil / water ratio. There is no particular limitation on the oil / water ratio of the drilling fluid composition of the present invention. In some embodiments, the drilling fluid composition has an oil / water ratio of 50 / 50 to 99.9 / 0.1, such as 55 / 45 to 99 / 1, 60 / 40 to 98 / 2, or 65 / 35 to 95 / 5.

[0066] Additional components

[0067] As described above, drilling fluids known in the art generally also include additives. For example, conventional drilling fluids may include viscosity improvers, pH improvers, density improvers, filtration improvers, shale inhibitors, or combinations thereof. The drilling fluid composition of the present invention may include similar components.

[0068] In some embodiments, the drilling fluid composition comprises a viscosity modifier, sometimes referred to as a tackifier. A viscosity modifier is generally a compound used to increase the viscosity of a drilling fluid composition. Examples of viscosity modifiers suitable for use in drilling fluid compositions include organic affinity clays such as bentonite, hectorite, organo-attapulgite, montmorillonite, and smectite. In some cases, the viscosity modifier may comprise an organic affinity clay that has been modified with, for example, sodium carbonate, a long chain synthetic polymer, carboxymethyl cellulose, starch, or a polyphosphate.

[0069] In addition to the viscosity improver, the emulsified water phase in the drilling fluid composition contributes to the fluid viscosity.Thus, the condensation products of the present invention contribute to the viscosity of the drilling fluid composition because they increase the stability of the emulsion.

[0070] In some embodiments, the drilling fluid composition comprises a pH modifier, particularly an additive capable of controlling the alkalinity of the drilling fluid composition. Examples of suitable pH modifiers include calcium carbonate, calcium hydroxide (e.g., lime), potassium hydroxide (e.g., caustic potash), and sodium hydroxide (e.g., caustic soda).

[0071] In some embodiments, the drilling fluid composition includes a density modifier, sometimes referred to as a weighting agent. A density modifier is a finely divided solid material having a high specific gravity (or high density). Density modifiers are used to change, for example, increase, the density of the drilling fluid composition. Examples of density modifiers suitable for use in the drilling fluid composition include barite (minimum specific gravity of 4.20 g / cm 3 ), hematite (minimum specific gravity is 5.05g / cm 3 ), calcium carbonate (specific gravity 2.7-2.8g / cm 3 ), siderite (specific gravity is about 3.8g / cm 3 ) and ilmenite (specific gravity is about 4.6g / cm 3 ).

[0072] In some embodiments, the drilling fluid composition comprises a filtration improver, particularly an improver for high pressure, high temperature filtration. The high pressure, high temperature filtration test is a standard method for detecting the static filtration behavior of drilling fluids (e.g., water-based muds or oil-based muds) at high temperatures up to about 380°F, and is usually tested according to API standards. In order to improve the performance of the drilling fluid composition, a filtration improver may be added. Examples of suitable filtration improvers include organic affinity lignite, asphalt, and polymer materials.

[0073] In some embodiments, the drilling fluid composition comprises a shale inhibitor. Shale is a fine-grained, splittable, dendritic sedimentary rock formed by the consolidation of clay and silt-sized particles into relatively impermeable thin layers. When in contact with the drilling fluid, shale typically hydrates, swells and disintegrates. This is typically detrimental to drilling operations. Therefore, a shale inhibitor may be added to slow down or prevent the hydration, swelling or disintegration of the shale. Suitable examples of shale inhibitors include calcium halides, such as calcium chloride. In some cases, the shale inhibitor may be dissolved in the aqueous component of the drilling fluid composition.

[0074] As used herein, the terms "greater than" and "less than" limits may also include the numerical values ​​associated therewith. In other words, "greater than" and "less than" may be interpreted as "greater than or equal to" and "less than or equal to". It is contemplated that this statement may be amended in subsequent claims to include "or equal to". For example, "greater than 4.0" may be interpreted and amended in subsequent claims to "greater than or equal to 4.0".

[0075] These components mentioned herein may be considered optional components. In some cases, the compositions described herein may explicitly exclude one or more of the above components in this subsection, such as by claim formulation. For example, the claims may be modified to describe that the disclosed compositions, methods, etc. do not use or contain one or more of the above components, such as a composition that does not contain a density modifier.

[0076] Performance characteristics

[0077] The drilling fluid composition advantageously exhibits improved performance characteristics, such as stability. In some cases, the drilling fluid composition exhibits improved stability (compared to conventional drilling fluid compositions). In other words, the drilling fluid composition of the present invention can remain in an emulsion state for a long time. In some cases, the drilling fluid composition remains a stable emulsion (e.g., at room temperature) for a period of at least 1 hour, such as at least 2 hours, at least 3 hours, at least 4 hours, at least 5 hours, at least 6 hours, at least 8 hours, at least 10 hours, at least 12 hours, at least 18 hours, or at least 24 hours.

[0078] The drilling fluid composition also advantageously exhibits improved rheological properties. Two properties of particular relevance are the plastic viscosity (also known as yield stress) of the drilling fluid and the yield point of the drilling fluid. The yield stress corresponds to the point when the drilling fluid begins to deform plastically. The yield stress can be measured using a rotational standard viscometer (e.g. ) is measured by testing the rheological properties of the drilling fluid. Because the yield stress represents the upper limit of the force that can be applied without permanent delamination, the maximum usable load in a mechanical component can be determined from the yield stress, which is called the yield point.

[0079] The rheological properties, and hence the yield stress and yield point, of a drilling fluid may vary with temperature.

[0080] According to standard API 13A, the dispersed plastic viscosity should be above 10 cP. In some embodiments, the drilling fluid composition shows a plastic viscosity at 25°C greater than 15 cP, such as greater than 16 cP, greater than 17 cP, greater than 18 cP, greater than 19 cP, or greater than 20 cP. In terms of upper limits, the plastic viscosity of the drilling fluid composition at 25°C may be less than 40 cP, such as less than 39 cP, less than 38 cP, less than 37 cP, less than 36 cP, or less than 35 cP. In terms of ranges, the plastic viscosity of the drilling fluid composition at 25° C. may be in the range of 15 cP to 40 cP, e.g., 15 cP to 39 cP, 15 cP to 38 cP, 15 cP to 37 cP, 15 cP to 36 cP, 15 cP to 35 cP, 16 cP to 40 cP, 16 cP to 39 cP, 16 cP to 38 cP, 16 cP to 37 cP, 16 cP to 36 cP, 16 cP to 35 cP, 17 cP to 40 cP, 17 cP to 39 cP, 17 cP to 38 cP, 17 cP to 37 cP, 17 cP to 36cP, 17cP to 35cP, 18cP to 40cP, 18cP to 39cP, 18cP to 38cP, 18cP to 37cP, 18cP to 36cP, 18cP to 35cP, 19cP to 40cP, 19cP to 39cP, 19cP to 38cP, 19cP to 37cP, 19cP to 36cP, 19cP to 35cP, 20cP to 40cP, 20cP to 39cP, 20cP to 38cP, 20cP to 37cP, 20cP to 36cP, or 20cP to 35cP.

[0081] In some embodiments, the drilling fluid composition exhibits a plastic viscosity at 80° C. greater than 8 cP, such as greater than 9 cP, greater than 176 cP, greater than 11 cP, greater than 12 cP, or greater than 13 cP. In terms of upper limits, the drilling fluid composition may have a plastic viscosity at 80° C. of less than 30 cP, such as less than 29 cP, less than 28 cP, less than 27 cP, less than 26 cP, or less than 25 cP. In terms of ranges, the plastic viscosity of the drilling fluid composition at 80° C. may be in the range of 8 cP to 30 cP, e.g., 8 cP to 29 cP, 8 cP to 28 cP, 8 cP to 27 cP, 8 cP to 26 cP, 8 cP to 25 cP, 9 cP to 30 cP, 9 cP to 29 cP, 9 cP to 28 cP, 9 cP to 27 cP, 9 cP to 26 cP, 9 cP to 25 cP, 10 cP to 30 cP, 10 cP to 29 cP, 10 cP to 28 cP, 10 cP to 27 cP, 10 cP to 26 cP, 10 cP to 25 cP. 0cP to 25cP, 11cP to 30cP, 11cP to 29cP, 11cP to 28cP, 11cP to 27cP, 11cP to 26cP, 11cP to 25cP, 12cP to 30cP, 12cP to 29cP, 12cP to 28cP, 12cP to 27cP, 12cP to 26cP, 12cP to 25cP, 13cP to 30cP, 13cP to 29cP, 13cP to 28cP, 13cP to 27cP, 13cP to 26cP, or 13cP to 25cP.

[0082] In some embodiments, the drilling fluid composition exhibits a yield point at 25°C greater than 15 lb / 100 ft 2 , for example greater than 16lb / 100ft 2 , greater than 17lb / 100ft 2 , greater than 18lb / 100ft 2 , greater than 19lb / 100ft 2 , or greater than 20lb / 100ft 2 As an upper limit, the yield point of the drilling fluid composition at 25°C may be less than 40 lb / 100 ft 2 , for example less than 39lb / 100ft 2 , less than 38lb / 100ft 2 , less than 37lb / 100ft 2 , less than 36lb / 100ft 2 , or less than 35lb / 100ft 2 In terms of ranges, the yield point of the drilling fluid composition at 25°C may be between 15 lb / 100 ft 2 Up to 40lb / 100ft 2In the range, for example, 15lb / 100ft 2 Up to 39lb / 100ft 2 , 15lb / 100ft 2 Up to 38lb / 100ft 2 , 15lb / 100ft 2 Up to 37lb / 100ft 2 , 15lb / 100ft 2 Up to 36lb / 100ft 2 , 15lb / 100ft 2 Up to 35lb / 100ft 2 , 16lb / 100ft 2 Up to 40lb / 100ft 2 , 16lb / 100ft 2 Up to 39lb / 100ft 2 , 16lb / 100ft 2 Up to 38lb / 100ft 2 , 16lb / 100ft 2 Up to 37lb / 100ft 2 , 16lb / 100ft 2 Up to 36lb / 100ft 2 , 16lb / 100ft 2 Up to 35lb / 100ft 2 , 17lb / 100ft 2 Up to 40lb / 100ft 2 , 17lb / 100ft 2 Up to 39lb / 100ft 2 , 17lb / 100ft 2 Up to 38lb / 100ft 2 , 17lb / 100ft 2 Up to 37lb / 100ft 2 , 17lb / 100ft 2 Up to 36lb / 100ft 2 , 17lb / 100ft 2 Up to 35lb / 100ft 2 , 18lb / 100ft 2 Up to 40lb / 100ft 2 , 18lb / 100ft 2 Up to 39lb / 100ft 2 , 18lb / 100ft 2 Up to 38lb / 100ft 2 , 18lb / 100ft 2 Up to 37lb / 100ft2 , 18lb / 100ft 2 Up to 36lb / 100ft 2 , 18lb / 100ft 2 Up to 35lb / 100ft 2 , 19lb / 100ft 2 Up to 40lb / 100ft 2 , 19lb / 100ft 2 Up to 39lb / 100ft 2 , 19lb / 100ft 2 Up to 38lb / 100ft 2 , 19lb / 100ft 2 Up to 37lb / 100ft 2 , 19lb / 100ft 2 Up to 36lb / 100ft 2 , 19lb / 100ft 2 Up to 35lb / 100ft 2 , 20lb / 100ft 2 Up to 40lb / 100ft 2 , 20lb / 100ft 2 Up to 39lb / 100ft 2 , 20lb / 100ft 2 Up to 38lb / 100ft 2 , 20lb / 100ft 2 Up to 37lb / 100ft 2 , 20lb / 100ft 2 Up to 36lb / 100ft 2 , or 20lb / 100ft 2 Up to 35lb / 100ft 2 .

[0083] In some embodiments, the drilling fluid composition exhibits a yield point at 80°C of greater than 8 lb / 100 ft 2 , for example greater than 9lb / 100ft 2 , greater than 176lb / 100ft 2 , greater than 11lb / 100ft 2 , greater than 12lb / 100ft 2 , or greater than 13lb / 100ft 2 As an upper limit, the yield point of the drilling fluid composition at 80°C may be less than 30 lb / 100 ft 2 , for example less than 29lb / 100ft 2 , less than 28lb / 100ft 2, less than 27lb / 100ft 2 , less than 26lb / 100ft 2 , or less than 25lb / 100ft 2 In terms of range, the yield point of a drilling fluid composition at 80°C may be 8 lb / 100 ft 2 Up to 30lb / 100ft 2 , for example 8lb / 100ft 2 Up to 29lb / 100ft 2 , 8lb / 100ft 2 Up to 28lb / 100ft 2 , 8lb / 100ft 2 Up to 27lb / 100ft 2 , 8lb / 100ft 2 Up to 26lb / 100ft 2 , 8lb / 100ft 2 Up to 25lb / 100ft 2 , 9lb / 100ft 2 Up to 30lb / 100ft 2 , 9lb / 100ft 2 Up to 29lb / 100ft 2 , 9lb / 100ft 2 Up to 28lb / 100ft 2 , 9lb / 100ft 2 Up to 27lb / 100ft 2 , 9lb / 100ft 2 Up to 26lb / 100ft 2 , 9lb / 100ft 2 Up to 25lb / 100ft 2 , 176lb / 100ft 2 Up to 30lb / 100ft 2 , 176lb / 100ft 2 Up to 29lb / 100ft 2 , 176lb / 100ft 2 Up to 28lb / 100ft 2 , 176lb / 100ft 2 Up to 27lb / 100ft 2 , 176lb / 100ft 2 Up to 26lb / 100ft 2 , 176lb / 100ft 2 Up to 25lb / 100ft 2 , 11lb / 100ft 2 Up to 30lb / 100ft2 , 11lb / 100ft 2 Up to 29lb / 100ft 2 , 11lb / 100ft 2 Up to 28lb / 100ft 2 , 11lb / 100ft 2 Up to 27lb / 100ft 2 , 11lb / 100ft 2 Up to 26lb / 100ft 2 , 11lb / 100ft 2 Up to 25lb / 100ft 2 , 12lb / 100ft 2 Up to 30lb / 100ft 2 , 12lb / 100ft 2 Up to 29lb / 100ft 2 , 12lb / 100ft 2 Up to 28lb / 100ft 2 , 12lb / 100ft 2 Up to 27lb / 100ft 2 , 12lb / 100ft 2 Up to 26lb / 100ft 2 , 12lb / 100ft 2 Up to 25lb / 100ft 2 , 13lb / 100ft 2 Up to 30lb / 100ft 2 , 13lb / 100ft 2 Up to 29lb / 100ft 2 , 13lb / 100ft 2 Up to 28lb / 100ft 2 , 13lb / 100ft 2 Up to 27lb / 100ft 2 , 13lb / 100ft 2 Up to 26lb / 100ft 2 , or 13lb / 100ft 2 Up to 25lb / 100ft 2 .

[0084] According to standard API 13A, the ratio between yield point and plastic viscosity should be less than 1.50. In some embodiments, the drilling fluid composition shows a ratio between yield point and plastic viscosity of less than 2, such as less than 1.75, less than 1.50, less than 1.25, or less than 1. In terms of lower limits, the drilling fluid composition can show a ratio between yield point and plastic viscosity greater than 0.1, such as greater than 0.2, greater than 0.3, greater than 0.4, or greater than 0.5. In terms of ranges, the drilling fluid composition can exhibit a ratio between yield point and plastic viscosity in the range of 0.1-2, such as 0.1-1.75, 0.1-1.50, 0.1-1.25, 0.1-1; 0.2-2, such as 0.2-1.75, 0.2-1.50, 0.2-1.25, 0.2-1; 0.3-2, such as 0.3-1.75, 0.3-1.50, 0.3-1.25, 0.3-1; 0.4-2, such as 0.4-1.75, 0.4-1.50, 0.4-1.25, 0.4-1; 0.5-2, such as 0.5-1.75, 0.5-1.50, 0.5-1.25, or 0.5-1.

[0085] Preparation of drilling fluid composition

[0086] The present invention also provides methods for preparing the drilling fluid compositions described herein. These methods include reacting a trifunctional amine and a fatty acid (as described in detail below) to form a condensation product, and adding the condensation product to an oil-based fluid to form a drilling fluid composition. In some embodiments, the method further includes adding a viscosity improver, a pH improver, a density improver, a filtration improver, an aqueous component, a shale inhibitor, or a combination thereof to the oil-based fluid.

[0087] The inventors have developed a synthetic route for preparing the condensation products of the present invention without the need for the use of hazardous reagents. In some embodiments, the condensation reaction is carried out by combining a trifunctional amine and a fatty acid and heating the mixture. In some embodiments, for example, in a laboratory-scale synthesis operation, the mixture can be heated with standard laboratory equipment, such as a Bunsen burner, a steam bath, an electric heating mantle, or a hot plate. In these embodiments, the mixture can be heated under reflux using methods known to those skilled in the art.

[0088] In one embodiment, the condensation reaction comprises heating the trifunctional amine and the fatty acid to a temperature of at least 100° C., e.g., at least 105° C., at least 110° C., at least 115° C., at least 120° C., or at least 125° C. In terms of upper limits, the condensation reaction can comprise heating the reaction mixture to a temperature of less than 300° C., e.g., less than 275° C., less than 250° C., less than 225° C., less than 200° C., or less than 175° C. In terms of ranges, the condensation reaction may include heating the reaction mixture to a temperature in the range of 100°C to 300°C, e.g., 110°C to 300°C, 115°C to 300°C, 120°C to 300°C, 125°C to 300°C, 100°C to 275°C, 110°C to 275°C, 115°C to 275°C, 120°C to 275°C, 125°C to 275°C, 100°C to 250°C, 110°C to 250°C, 115°C to 250°C, 120°C to 300°C, 125°C to 300°C, to 250°C, 125°C to 250°C, 100°C to 225°C, 110°C to 225°C, 115°C to 225°C, 120°C to 225°C, 125°C to 225°C, 100°C to 200°C, 110°C to 200°C, 115°C to 200°C, 120°C to 200°C, 125°C to 200°C, 100°C to 175°C, 110°C to 175°C, 115°C to 175°C, 120°C to 175°C, or 125°C to 175°C.

[0089] In one embodiment, the condensation reaction comprises heating the trifunctional amine and the fatty acid for a period of at least 10 hours, such as at least 12 hours, at least 14 hours, at least 16 hours, at least 18 hours, or at least 20 hours. In terms of upper limits, the condensation reaction may comprise heating the reaction mixture for a period of less than 50 hours, such as less than 45 hours, less than 40 hours, less than 35 hours, less than 30 hours, or less than 25 hours. In terms of ranges, the condensation reaction may comprise heating the reaction mixture for a period of 10-50 hours, such as 12-50 hours, 14-50 hours, 16-50 hours, 18-50 hours, 20-50 hours, 10-45 hours, 12-45 hours, 14-45 hours, 16-45 hours, 18-45 hours, 20-45 hours, 10-40 hours, 12-40 hours, 14-40 hours, 16-40 hours, 18- 40 hours, 20-40 hours, 10-35 hours, 12-35 hours, 14-35 hours, 16-35 hours, 18-35 hours, 20-35 hours, 10-30 hours, 12-30 hours, 14-30 hours, 16-30 hours, 18-30 hours, 20-30 hours, 10-25 hours, 12-25 hours, 14-25 hours, 16-25 hours, 18-25 hours, or 20-25 hours.

[0090] In some embodiments, the operation of conducting the condensation reaction as described above obtains a condensation product comprising less than 15 wt % impurities, e.g., less than 14 wt %, less than 13 wt %, less than 12 wt %, less than 11 wt %, or less than 10 wt %.

[0091] In some cases, the progress of the condensation reaction and / or the purity of the condensation product can be monitored by spectroscopy. 1 H NMR spectroscopy is used to monitor the progress and / or purity. In these embodiments, a sample of the reaction mixture and / or condensation product can be diluted in a deuterated solvent, such as deuterated water, deuterated acetone, deuterated methanol, deuterated dimethyl sulfoxide (DMSO), or deuterated chloroform. In a preferred embodiment, the sample is diluted in deuterated DMSO. Figure 1 As shown, the progress and / or purity can be assessed by the disappearance of the peak representing carboxylic acid protons (about 12 ppm) and the appearance of the peak representing amide protons (about 7 ppm).

[0092] The progress of the condensation reaction and / or the purity of the condensation product can also be detected by other spectroscopic or spectral methods. For example, the progress and / or purity can be detected by infrared spectroscopy, Raman spectroscopy, GC-MS, LC-MS, HPLC and other conventional methods known to those skilled in the art.

[0093] In some embodiments, a condensation reaction occurs during use of the drilling fluid composition. For example, the condensation product can be formed in situ. Because the condensation reaction involves heating the trifunctional amine and the fatty acid and does not require the use of additional reagents, the condensation reaction can be carried out in any high temperature environment. In some embodiments, the trifunctional amine and the fatty acid can be used for high temperature metal substrates.

[0094] In some embodiments, for example, the trifunctional amine and the fatty acid can be pumped into an underground formation or a wellbore, and a condensation product can be formed in the underground formation. In the underground formation or wellbore, one or more metal substrates can be exposed to an elevated temperature. The metal substrate can be exposed to a temperature high enough to drive the condensation reaction. In one embodiment, the metal substrate is exposed to a temperature of at least 100°C, such as at least 105°C, at least 110°C, at least 115°C, at least 120°C, or at least 125°C.

[0095] As described herein, the method of the present invention includes adding the condensation product to an oil-based fluid to form a drilling fluid composition, and optionally adding a viscosity modifier, a pH modifier, a density modifier, a filtration modifier, an aqueous component, a shale inhibitor, or a combination thereof to the oil-based fluid. In each case, there are no particular limitations on the method of addition, and any conventional means may be used. In some embodiments, for example, the operation for adding the condensation product to the oil-based fluid includes stirring, mixing, vibrating, and / or agitating the mixture, for example, by mechanical means.

[0096] Application of drilling fluid composition

[0097] The drilling fluid composition can be used in the same manner as conventional drilling fluids. In particular, the drilling fluid composition can be used during conventional oil and gas operations. In some cases, for example, the drilling fluid composition can be pumped into a wellbore during drilling. Example

[0098] The present invention may be better understood with reference to the following non-limiting examples.

[0099] Example 1

[0100] Several drilling fluid compositions were prepared, which contained condensation products of triaminononane (TAN) and tall oil fatty acid (TOFA). The condensation products were prepared at a weight ratio of 1:1 between TAN and TOFA. These drilling fluid compositions were prepared using different amounts of the condensation products to achieve the final concentration in the entire drilling fluid composition. In each case, the drilling fluid composition contained a viscosity improver (modified hectorite, organo-attapulgite), a pH improver (lime), a density improver (calcium carbonate), a filtration improver (organic affinity lignite) and a shale inhibitor (calcium chloride). These compositions are shown in Table 1 below.

[0101] Table 1: Exemplary Drilling Fluid Compositions

[0102]

[0103] The results were obtained using a rotational viscometer ( Grace M3600) was used to test the rheological properties. The rheological tests were carried out at fixed speeds of 600 rpm, 300 rpm, 200 rpm, 100 rpm, 60 rpm, 30 rpm, 6 rpm and 3 rpm, respectively, which resulted in Newtonian shear rates of 102.38 s on the internal fixed cylinder. -1 , 510.67s -1 、340.46s -1 、170.32s -1 , 102.14s -1, 51.069s -1 、10.21s -1 and 5.11s -1 The rotation at each rotation speed was continued for 60 seconds and the values ​​were read every 10 seconds. Six values ​​were averaged and recorded. The yield stress was determined from the rheogram (shear stress versus shear rate) by obtaining an extrapolated curve for zero shear rate and fitting a suitable rheological model. Table 2 lists the results of the rheological tests, in particular the plastic viscosity (PV) and yield point (YP) at different temperatures.

[0104] Table 2: Rheological Behavior of Exemplary Drilling Fluid Compositions

[0105]

[0106] As shown in Table 2, the drilling fluid compositions exhibit desirable high plastic viscosity and yield point. Except for Examples 1 and 2 at 93°C, all compositions tested exhibited plastic viscosities greater than 10 cP measured according to API 13A. In addition, Examples 1-4 each exhibited a desirable low ratio between yield point and plastic viscosity. In particular, none of the compositions tested exhibited a ratio greater than 1.5, and some of the compositions even exhibited a ratio less than 1.

[0107] Example 2

[0108] Another test was conducted to evaluate the stability of the drilling fluid composition. In particular, this test evaluated the ability of the condensation product to maintain an emulsion. For this test, a condensation product of TAN and TOFA was prepared as described above using a 1:1 weight ratio between TAN and TOFA. The condensation product was added to a mixture of 20 volume % water and 80 volume % mineral oil at various concentrations. These mixtures were vibrated to form an emulsion and observed over time to determine whether the emulsion was stable. Table 3 reports the results.

[0109] Table 3: Stabilizing effect of condensation products

[0110]

[0111] As shown in Table 3, at all concentrations, the condensation products remained stable emulsions for a period of at least 2 hours. As the concentration increased, the stability of the emulsions also increased. These results indicate that the condensation products, especially at higher concentrations, can suitably emulsify typical water-in-oil emulsions in drilling fluid compositions.

[0112] Implementation

[0113] The present invention contemplates the following embodiments. All combinations of these features and embodiments are contemplated.

[0114] Embodiment 1: A drilling fluid composition comprising: 0.1 wt % to 10 wt % of a condensation product of a trifunctional amine and a fatty acid, wherein the weight ratio between the trifunctional amine and the fatty acid in the condensation product is in the range of 0.1:1 to 10:1; and an oil-based fluid.

[0115] Embodiment 2: An embodiment according to embodiment 1, wherein the weight ratio between the trifunctional amine and the fatty acid in the condensation product is 0.3:1 to 2:1.

[0116] Embodiment 3: The embodiment according to embodiment 1 or 2, wherein the drilling fluid composition exhibits a plastic viscosity at 25°C greater than 15 cP.

[0117] Embodiment 4: The embodiment according to any one of embodiments 1-3, wherein the drilling fluid composition exhibits a plastic viscosity at 80°C greater than 10 cP.

[0118] Embodiment 5: An embodiment according to any one of embodiments 1-4, wherein the drilling fluid composition exhibits a yield point at 25°C greater than 15 lb / 100 ft 2 .

[0119] Embodiment 6: An embodiment according to any one of embodiments 1-5, wherein the drilling fluid composition exhibits a yield point at 80°C greater than 10 lb / 100 ft 2 .

[0120] Embodiment 7: The embodiment according to any one of embodiments 1-6, wherein the drilling fluid composition exhibits a ratio between yield point and plastic viscosity of less than 2.

[0121] Embodiment 8: The embodiment according to any one of embodiments 1-7, further comprising a viscosity improver, a pH improver, a density improver, a filtration improver, an aqueous component, a shale inhibitor, or a combination thereof.

[0122] Embodiment 9: The embodiment according to any one of embodiments 1-8, wherein the oil-based fluid comprises diesel, mineral oil, linear olefins, linear alkanes, or combinations thereof.

[0123] Embodiment 10: An embodiment according to any one of embodiments 1-9, wherein the trifunctional amine contains 6-12 carbon atoms.

[0124] Embodiment 11: An embodiment according to any one of embodiments 1-10, wherein the trifunctional amine has the following chemical formula:

[0125] C x H y (NH2)3,

[0126] where x is 6-12; and

[0127] Where y is less than or equal to 23.

[0128] Embodiment 12: An embodiment according to any one of embodiments 1-11, wherein the fatty acid comprises palmitic acid, oleic acid, linoleic acid, abietic acid, (Z)-6-hexadecenoic acid, palmitoleic acid, myristic acid, elaidic acid, 11-octadecenoic acid, or tall oil, isomers thereof, or combinations thereof.

[0129] Embodiment 13: A method for preparing a drilling fluid composition, comprising:

[0130] reacting a trifunctional amine and a fatty acid at a temperature of at least 100° C. for at least 10 hours to form a condensation product; and

[0131] adding the condensation product to an oil-based fluid to form a drilling fluid composition;

[0132] The condensation product contains less than 15% by weight of impurities.

[0133] Embodiment 14: According to the embodiment described in Embodiment 13, it also includes adding a viscosity improver, a pH improver, a density improver, a filtration improver, an aqueous component, a shale inhibitor or a combination thereof to the oil-based fluid.

[0134] Embodiment 15: The embodiment according to embodiment 13 or 14, wherein the oil-based fluid comprises diesel, mineral oil, linear olefins, linear alkanes or combinations thereof.

[0135] Embodiment 16: An embodiment according to embodiments 13-15, wherein the trifunctional amine contains 6-12 carbon atoms.

[0136] Embodiment 17: According to the embodiment described in embodiment 13-16, wherein the trifunctional amine has the following chemical formula:

[0137] C x H y (NH2)3,

[0138] where x is 6-12; and

[0139] Where y is less than or equal to 23.

[0140] Embodiment 18: According to the embodiment described in embodiments 13-17, the fatty acid comprises palmitic acid, oleic acid, linoleic acid, abietic acid, (Z)-6-hexadecenoic acid, palmitoleic acid, myristic acid, elaidic acid, 11-octadecenoic acid, or tall oil, its isomers, or a combination thereof.

Claims

1. A drilling fluid composition comprising: 0.1 to 10 wt % of a condensation product of a trifunctional amine and a fatty acid, wherein the weight ratio between the trifunctional amine and the fatty acid is in the range of 0.1:1 to 10:1; and Oil-based fluids; The condensation product corresponds to formula 1: wherein R1 is an alkyl, alkenyl or alkynyl group having 8 to 24 carbon atoms, R2 is an alkyl, alkenyl or alkynyl group having 1 to 4 carbon atoms, R3 is an alkyl, alkenyl or alkynyl group having 1 to 4 carbon atoms, R4 is HN-alkyl having 1 to 4 carbon atoms.

2. The drilling fluid composition of claim 1, wherein the weight ratio between the trifunctional amine and the fatty acid is in the range of 0.3:1 to 2:

1.

3. The drilling fluid composition of claim 1, wherein the condensation product corresponds to Formula 2b:

4. The drilling fluid composition of claim 1, wherein the drilling fluid composition exhibits a plastic viscosity at 25°C greater than 15 cP, or a plastic viscosity at 80°C greater than 10 cP.

5. The drilling fluid composition of claim 1, wherein the drilling fluid composition exhibits a yield point at 25°C greater than 15 lb / 100 ft 2 , or the yield point at 80℃ is greater than 10lb / 100ft 2 .

6. The drilling fluid composition of claim 1, wherein the drilling fluid composition shows a ratio between yield point and plastic viscosity according to standard API 13A of less than 2.

7. The drilling fluid composition of claim 1, further comprising a viscosity improver, a pH improver, a density improver, a filtration improver, an aqueous component, a shale inhibitor or a combination thereof, wherein the filtration improver comprises lignite, bitumen and a polymer material with organic affinity and wherein the aqueous component is water or brine.

8. The drilling fluid composition of claim 1, wherein the oil-based fluid comprises mineral oil, linear olefins, linear alkanes, or combinations thereof.

9. The drilling fluid composition of claim 1, wherein the trifunctional amine contains 6 to 12 carbon atoms.

10. The drilling fluid composition of claim 1, wherein the trifunctional amine has the following chemical formula: C x H y (NH2)3, where x is 6-12; and Where y is less than or equal to 23.

11. The drilling fluid composition of claim 1, wherein the fatty acid comprises palmitic acid, oleic acid, linoleic acid, abietic acid, (Z)-6-hexadecenoic acid, palmitoleic acid, myristic acid, elaidic acid, 11-octadecenoic acid, or tall oil, isomers thereof, or combinations thereof.

12. The drilling fluid composition of claim 1, wherein the oil-based fluid comprises diesel fuel.

13. A method for preparing a drilling fluid composition according to any one of claims 1 to 12, comprising: reacting a trifunctional amine with a fatty acid at a temperature of at least 100° C. for at least 10 hours to form a condensation product; and adding the condensation product to an oil-based fluid to form a drilling fluid composition; The condensation product contains less than 15% by weight of impurities.

14. The method of claim 13, further comprising adding a viscosity improver, a pH improver, a density improver, a filtration improver, an aqueous component, a shale inhibitor or a combination thereof to an oil-based fluid, wherein the oil-based fluid comprises mineral oil, linear olefins, linear alkanes or a combination thereof, wherein the filtration improver comprises lignite, asphalt and polymer materials with organic affinity and wherein the aqueous component is water or brine.

15. The method of claim 13, wherein the trifunctional amine has the following formula: C x H y (NH2)3, where x is 6-12; and Where y is less than or equal to 23.

16. The method of claim 13, wherein the fatty acid comprises palmitic acid, oleic acid, linoleic acid, abietic acid, (Z)-6-hexadecenoic acid, palmitoleic acid, myristoleic acid, elaidic acid, 11-octadecenoic acid, or tall oil, isomers thereof, or combinations thereof.

17. The method of claim 13, wherein the trifunctional amine comprises 6 to 12 carbon atoms.

18. The method of claim 13, wherein the oil-based fluid comprises diesel fuel.

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