Self-aggregating particles for leak stoppage materials and related methods

Abstract

The leak stoppage material may include a plurality of self-aggregating particles having a degradable coating, where the self-aggregating particles are capable of binding into a plurality of aggregated particles via mechanical interaction, electrical interaction, magnetic interaction, chemical interaction, or any combination thereof. The aggregated particles have a larger effective size and are capable of sealing large openings / bores underground that result in cyclic leakage during wellbore drilling operations.

Description

Technical Field

[0001] This disclosure generally relates to sealing materials and related methods. Background Technology

[0002] Lost circulation can occur at any stage of operation and happens when some or all of the drilling fluid (such as drilling mud) pumped into the well returns to the surface. While some degree of fluid loss is expected, excessive fluid loss is undesirable from a safety, economic, or environmental perspective. Lost circulation is associated with well control problems, borehole instability, stuck pipe, failed well tests, poor post-completion oil and gas production, and formation damage due to mud particles clogging pores and throats. In extreme cases, lost circulation problems can force well abandonment.

[0003] Circulating leakage can occur in various formations, such as naturally fractured formations, cave-like formations, and highly permeable formations (e.g., formations with permeability greater than 500 millidarcy). Based on the amount of fluid or mud lost, circulating leakage can be classified as seepage, moderate, severe, and complete leakage.

[0004] To reduce circulating losses, plugging materials can be included in the drilling fluid. These plugging materials are materials such as particles, large enough to block permeable portions of the formation. Examples of plugging materials include nut shells and swellable polymers. The extent of fluid loss and the ability to control circulating losses using plugging materials depend on the type of formation in which the circulating losses occur. Summary of the Invention

[0005] The following summary outlines various details of this disclosure to provide a basic understanding. This summary is not an exhaustive overview of the disclosure, nor is it intended to identify certain elements of the disclosure or to define its scope. Rather, the primary purpose of this summary is to present some of the concepts of the disclosure in a simplified form before a more detailed description follows.

[0006] According to embodiments consistent with this disclosure, a method may include: drilling at least a portion of a wellbore through an underground formation using a drilling fluid comprising: a base fluid; a plurality of self-aggregating particles having a degradable coating, wherein the self-aggregating particles are capable of binding into a plurality of aggregate particles via mechanical interaction, electrical interaction, magnetic interaction, chemical interaction, or any combination thereof; and exposing the plurality of particles to a stimulus that causes a reduction in the thickness of the degradable coating, thereby exposing the bindable portions of the plurality of self-aggregating particles and allowing the plurality of self-aggregating particles to bind into a plurality of aggregate particles.

[0007] In another embodiment, the drilling fluid may include: a base fluid; and a plurality of self-aggregating particles having a biodegradable coating, wherein the self-aggregating particles are capable of aggregating into a plurality of aggregated particles via mechanical interaction, electrical interaction, magnetic interaction, chemical interaction, or any combination thereof.

[0008] In another embodiment, a composition may include: a plurality of self-aggregating particles having a biodegradable coating, wherein the self-aggregating particles are capable of combining into a plurality of aggregated particles via mechanical interaction, electrical interaction, magnetic interaction, chemical interaction, or any combination thereof.

[0009] Any combination of the various embodiments and implementations disclosed in this specification may be used in another embodiment consistent with this disclosure. The above and other aspects and features will be understood from the following description, drawings, and claims of certain embodiments proposed according to this disclosure. Attached Figure Description

[0010] Figure 1 A method for binding the self-aggregating particles of this disclosure is shown.

[0011] Figure 2A A plastic ball with hook-shaped protrusions is shown.

[0012] Figure 2B It shows a product coated with gelatin. Figure 2A A plastic ball with hook-shaped protrusions.

[0013] Figure 2C The image shows a ball coated with gelatin in stirred water at 22°C.

[0014] Figure 2D The images show balls in stirred water at 32°C after at least some gelatin has dissolved and plastic balls with hook-like protrusions have mechanically bonded together to form aggregated particles. Detailed Implementation

[0015] Embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. For consistency, similar elements may be denoted by similar reference numerals in the various drawings. Furthermore, numerous specific details are set forth in the following detailed description of embodiments of the present disclosure to provide a more thorough understanding of the claimed subject matter. However, it will be apparent to those skilled in the art that the embodiments disclosed herein may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description. Additionally, it will be apparent to those skilled in the art that the scale of the elements presented in the drawings may vary without departing from the scope of the present disclosure.

[0016] This disclosure generally relates to leak sealing materials (LCMs) and related methods. More specifically, the LCMs of this disclosure are self-aggregating particles with a biodegradable coating, wherein, upon exposure to a stimuli, the biodegradable coating at least partially degrades and allows multiple self-aggregating particles to combine into multiple aggregated particles.

[0017] Figure 1 A method 100 for binding the self-aggregating particles 104 of this disclosure is shown. The self-aggregating particles 104 have a biodegradable coating 102. The self-aggregating particles 104 shown include physical features (specifically, hook-shaped protrusions 106) that allow binding of the self-aggregating particles 104 to occur when the biodegradable coating 102 is at least partially degraded. The biodegradable coating 102 degrades upon exposure to a stimuli. The degradation of the biodegradable coating 102 exposes the hook-shaped protrusions 106, which causes the self-aggregating particles 104 to form interparticle binding forces 108 to produce aggregated particles 110.

[0018] Figure 1 An example of self-aggregating particles is shown, wherein the binding force 108 that generates aggregated particles 110 is mechanical (specifically, a hook). More generally, the self-aggregating particles of this disclosure can be bound together to generate aggregated particles via mechanical interactions, electrical interactions, magnetic interactions, chemical interactions, etc., or any combination thereof. The binding can be physical binding, chemical binding, magnetic binding, or a combination thereof.

[0019] The mechanical interactions that cause bonding can be achieved through the physical characteristics of the self-aggregating particles. Examples of physical characteristics can include, but are not limited to, hooks, protrusion-cavity pairs (e.g., protrusions that engage with cavities), complementary particle shapes, and any combination thereof. For a protrusion-cavity pair, each self-aggregating particle can have both a cavity and a protrusion. Alternatively, the self-aggregating particles can include a first particle with a cavity but no protrusions and a second particle with protrusions but no cavities. Complementary particle shapes are shapes in which particles interlock based on a multi-bend shape, like an S. Similar to protrusion-cavity pairs, this can be achieved through a single set of shape-interlocking particles, or through a pair (or more) of particles with different shapes that achieve mechanical bonding (e.g., a helical shape with a multi-bend shape).

[0020] The electrical interactions that cause bonding can be achieved through electrostatic attraction between particles with opposite charges, van der Waals interactions in submicron fine particles, or dipole-dipole interactions between electric dipoles.

[0021] The magnetic interactions that induce bonding can be achieved by magnetic particles or non-magnetic particles with embedded magnets, wherein the thickness of the degradable coating is used to control the magnetic interactions between the particles. For example, a sufficiently thick degradable coating can mitigate magnetic interactions. Then, upon sufficient degradation to a thinner coating thickness, self-aggregating magnetic particles can undergo magnetic bonding to produce larger aggregated particles.

[0022] The chemical interactions that cause bonding can include, but are not limited to, hydrophobic interactions (e.g., hydrophobic particles agglomerating in a hydrophilic environment), hydrophilic interactions (e.g., hydrophilic particles agglomerating in a hydrophobic environment), and capillary interactions at the interface. The ability of self-aggregating particles to bond using chemical interactions can be achieved through the material of the self-aggregating particles or through a coating (not a biodegradable coating) on ​​the self-aggregating particles.

[0023] The combination of the above can be used to generate aggregated particles. For example, both mechanical and chemical interactions can be used, where the surface of the self-aggregating particles facilitates bonding via chemical interactions, and the self-aggregating particles can be shaped (e.g., have protrusions) to facilitate bonding via mechanical interactions. Thus, if changes in the environment in which the aggregated particles are located weaken the chemical interactions, mechanical interactions can maintain the structural integrity of the aggregated particles.

[0024] Self-aggregating particles may have an average diameter of 0.1 mm to 2 mm (or 0.1 mm to 1 mm, or 0.5 mm to 2 mm, or 1 mm to 2 mm). Unless otherwise specified, the diameter of the particle or particle aggregate is the diameter of the smallest sphere into which the particle or particle aggregate can be placed. Unless otherwise specified, the average diameter of the particle or particle aggregate is the weight-average diameter.

[0025] Self-aggregating particles can have any shape, including but not limited to cones, capsules, spheres, ovals, discs, and any mixture thereof, with or without protrusions or other features for aggregation.

[0026] Self-aggregating particles can be formed from any suitable material. Examples of materials include, but are not limited to, polymers, ceramics, glass, metals, and any combination thereof. Examples of polymers include, but are not limited to, polyethylene (PE) (e.g., ultra-high density PE), polycarbonate (PC), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS) (e.g., high-impact PS), polymethyl methacrylate (PMMA), polyamides (e.g., including nylon, such as nylon 12 and glass fiber reinforced nylon), silicone, fluoropolymers (e.g., Polytetrafluoroethylene (PTFE), thermoplastic polyurethane (TPU), acrylonitrile-butadiene-styrene (ABS) triblock polymer, acrylic-styrene-acrylonitrile triblock polymer (ASA), polyarylether ether ketone (PAEK), polyether ether ketone (PEEK), polyetherimide (PEI), polyethylene terephthalate (PET), polylactic acid, epoxy resin, etc., and any combination thereof. Examples of ceramics and glasses may include, but are not limited to, crystalline oxides or glassy oxides, nitrides, silicates, carbides, etc., and any combination thereof. For example, ceramics and glasses may include alumina, aluminosilicate glass, aluminum nitride, boron nitride, borosilicate glass, cordierite, Corningware, etc. Graphite, volcanic rock (Grade A), lead glass, Mullite, quartz, sapphire, porcelain, silicon, silicon carbide, silicon nitride, soda-lime glass, Zirconia and any combination thereof. Examples of metals may include, but are not limited to, aluminum, brass, bronze, cobalt, chromium, copper, gold, platinum, steel (including stainless steel), silver, and titanium, their composites, and their alloys. The materials used for self-aggregating particles should be selected, at least in part, based on the environment to which the aggregated particles are exposed, so that the aggregated particles maintain sufficient structural integrity.

[0027] Self-aggregating particles can also come from natural sources. For example, seeds of the Tribulus terrestris plant can aggregate through protrusions on their surface.

[0028] Degradable coatings can be formed from any suitable material that thins upon exposure to a stimulus. Degradation can be chemical degradation (where the material is chemically transformed into another substance) and / or dissolution (where the material is removed from the coating by dissolving in the surrounding environment) and / or thinning (or shrinking) of the coating in response to a stimulus.

[0029] Examples of stimuli may include, but are not limited to, exposure to aqueous fluids, exposure to oily fluids, increases in temperature, externally applied electric fields, changes in pH, changes in ion concentration, and any combination thereof.

[0030] Examples of materials used for biodegradable coatings that will degrade the coating by dissolution when exposed to water (optionally accompanied by an additional temperature rise) may include, but are not limited to, gelatin, polyvinyl alcohol, polyethylene glycol, polysaccharides, carboxymethyl cellulose, polyacrylamide, polyacrylic acid, polyamine, polyethyleneimine, polyvinyl methyl ether, carboxylated polymethylene, polyvinylpyrrolidone, poly(N-alkyl)-substituted acrylamide, poly(N-vinylalkylamide), polyethylene oxide, polyester, polyether, and any combination thereof.

[0031] Examples of materials for biodegradable coatings that will degrade the coating via chemical degradation (and / or dissolution) when exposed to water (optionally accompanied by additional temperature rise) may include, but are not limited to, polylactide or polylactic acid (PLA), polyglycolic acid, polyglycolic acid (PGA), and any combination thereof.

[0032] Examples of materials used for biodegradable coatings that will degrade the coating by dissolution when exposed to oily fluids (optionally accompanied by additional temperature rise) may include, but are not limited to, polystyrene, polyethylene, polypropylene, and any combination thereof.

[0033] Examples of materials for biodegradable coatings that reduce swelling and cause the coating to shrink when exposed to different pH values ​​may include, but are not limited to, chitosan, guar gum, alginate, carboxymethyl dextran, and any combination thereof.

[0034] A biodegradable coating can be applied to all or some of the self-aggregating particles. For example, 25% to 100% of the surface area of ​​the self-aggregating particles can be coated with a biodegradable coating. For example, the biodegradable coating can cover the portion of the self-aggregating particles that can bond together, and minimally cover (if any) the other portions of the self-aggregating particles.

[0035] Degradable coatings can be single-layer (e.g., as shown in the image) Figure 1 (as shown) or multiple layers. When using multiple layers, these layers may include at least two different materials suitable for the biodegradable coating, which are different and respond to different stimuli. For example, a dual-coating layer may include: an outer layer comprising a material that is water-soluble at moderate temperatures; and an inner layer that is water-soluble at higher temperatures.

[0036] Biodegradable coatings (cumulative multilayers) can have a maximum thickness of 1 μm to 100 μm. The biodegradable coating (before degradation) can account for 10% or less of the particle diameter (or 0.1% to 10%, or 0.1% to 5%, or 1% to 10%).

[0037] Aggregates can have an average diameter of 3 mm or larger (or 3 mm to 10 mm). Alternatively, aggregates may not have a fixed size, as their size can continue to increase over time.

[0038] The self-aggregating particles disclosed herein can be used as plugging materials in wellbore fluids (e.g., drilling fluids).

[0039] Drilling fluids may include a base fluid and self-aggregating particles of this disclosure having a biodegradable coating.

[0040] Self-aggregating particles with a biodegradable coating can be included in the drilling fluid in amounts ranging from 1 pound per barrel (ppb) to 60 ppb (or 1 ppb to 30 ppb, or 15 ppb to 45 ppb, or 30 ppb to 60 ppb).

[0041] The base fluid of drilling fluid can be an oil-based fluid or a water-based fluid.

[0042] Oily fluids can be any suitable fluid, such as oil or a solution containing oil and one or more organic or inorganic compounds dissolved in or otherwise completely miscible with the oil. Oily fluids can include at least one oil of a natural or synthetic origin. Oily fluids can include oils derived from petroleum, such as mineral oil; diesel oil; straight-chain or branched olefins; polyolefins; alkanes; paraffin wax; fatty acid esters; straight-chain, branched, or cyclic alkyl ethers of fatty acids; other petroleum-derived oils; or any combination thereof. Oily fluids can contain esters, ethers, acetals, dialkyl carbonates, hydrocarbons, or any combination thereof. Oily fluids can also include oils derived from, for example, animals or plants. Oily fluids can also include other oils, such as, but not limited to, polydiorganosiloxanes, siloxanes, organosiloxanes, other silicone-based oils, or combinations thereof.

[0043] Aqueous fluids can be any suitable fluid, such as water or a solution containing water and one or more organic or inorganic compounds dissolved in or otherwise completely miscible with water. Examples of water sources may include, but are not limited to, fresh water, well water, filtered water, distilled water, seawater, brine, produced water, formation brine, and any combination thereof. For example, aqueous fluids may contain brine, including natural and synthetic brine. Aqueous fluids may include water containing water-soluble organic compounds (e.g., alcohols, organic acids, amines, aldehydes, ketones, esters, or other polar organic compounds) or salts dissolved in water. In some embodiments, aqueous fluids may include salts, water-soluble organic compounds, or both, as impurities dissolved in water. Furthermore, aqueous fluids may include salts, water-soluble organic compounds, or both, to alter at least one property of the aqueous fluid, such as density or ion concentration. Increasing the amount of salts, water-soluble organic compounds, or both can increase the density of the drilling fluid. Examples of salts that can exist in aqueous fluids include, but are not limited to, metal salts such as sodium salts, calcium salts, cesium salts, zinc salts, aluminum salts, magnesium salts, potassium salts, strontium salts, silicates, lithium salts, and any combination thereof. Metal salts can be in the form of chlorides, bromides, carbonates, hydroxides, iodides, chlorates, bromates, formates, nitrates, sulfates, phosphates, oxides, fluorides, and any combination thereof.

[0044] Drilling fluids may also include other components, including but not limited to wetting agents, organophilic clays, thickeners, surfactants, dispersants, interfacial tension reducers or emulsifiers, rheology modifiers, pH buffers, mutual solvents, diluents, thinners, weighting agents, detergents, and any combination thereof.

[0045] Drilling fluids comprising a base fluid, self-aggregating particles with a biodegradable coating, and optional other components can be used in drilling operations, where the self-aggregating particles serve as a plugging material. For example, during drilling operations, drilling fluid is continuously pumped into the wellbore to clean and sanitize the wellbore and drilling debris (also known as drill cuttings). Drilling fluid is typically pumped from the mud pit into the wellbore and then returned to the surface. When the flow rate of drilling fluid returning to the surface is less than the flow rate of drilling fluid pumped into the wellbore, a circulating loss zone is encountered. This reduction or absence of returning drilling fluid is called circulating loss.

[0046] Drilling fluids containing self-aggregating particles with a biodegradable coating can be used in all or part of the drilling wellbore. For example, when encountering a circulating lost circulation zone, self-aggregating particles with a biodegradable coating can be added to the drilling fluid. Alternatively, self-aggregating particles with a biodegradable coating can be included in the drilling fluid regardless of whether a circulating lost circulation zone is encountered.

[0047] Once introduced into the wellbore, self-aggregating particles with a biodegradable coating may encounter stimuli. For example, circulating lost circulation zones containing formation-native fluids (e.g., water, acid (causing pH changes), or oil) can act as stimuli, causing the biodegradable coating to thin and exposing the bindable portions of the self-aggregating particles. This allows multiple self-aggregating particles to combine into multiple aggregates. In another example, bottomhole circulating temperature can serve as a stimuli. Multiple stimuli may be encountered upon introduction into the wellbore. Aggregates possess a larger effective size and are capable of sealing large openings / holes underground.

[0048] As an alternative to or in combination with natural stimuli, additives can be added to drilling fluids as stimuli. For example, after introducing self-aggregating particles with a biodegradable coating, water, oil, acid, or alkali can be introduced into the wellbore via drilling fluid (or via a separatory fluid). Thus, drilling fluid containing self-aggregating particles with a biodegradable coating can enter the formation in circulating lost circulation zones. Subsequently introduced additives can then contact the self-aggregating particles with the biodegradable coating, causing the biodegradable coating to thin and exposing the binding portions within the self-aggregating particles. This allows multiple self-aggregating particles to combine into multiple aggregates. The aggregates have a larger effective size and are capable of sealing large openings / holes underground.

[0049] Example

[0050] Bunchem balls (plastic balls with hook-shaped protrusions) Figure 2ACoated with gelatin ( Figure 2B Place the gelatin-coated Bunchem balls in stirred water at 22°C. Figure 2C The water temperature rose to 32℃. Figure 2D This causes the gelatin to dissolve in the water, and the Bunchem balls mechanically bind together to form aggregated particles.

[0051] Exemplary embodiments

[0052] The first exemplary embodiment disclosed in this specification includes: a method comprising: drilling at least a portion of a wellbore through an underground formation using a drilling fluid comprising: a base fluid; a plurality of self-aggregating particles having a degradable coating, wherein the self-aggregating particles are capable of binding into a plurality of aggregate particles via mechanical interaction, electrical interaction, magnetic interaction, chemical interaction, or any combination thereof; and exposing the plurality of particles to a stimulus that causes a reduction in the thickness of the degradable coating, thereby exposing the bindable portions of the plurality of self-aggregating particles and allowing the plurality of self-aggregating particles to bind into a plurality of aggregate particles. A first exemplary embodiment may have one or more of the following elements: Element 1: The method further includes introducing an additive into the wellbore, wherein the additive is a stimulant; Element 2: The biodegradable coating comprises a polymer selected from the group consisting of gelatin, polyvinyl alcohol, polyethylene glycol, polysaccharides, carboxymethyl cellulose, polyacrylamide, polyacrylic acid, polyamine, polyethyleneimine, polyvinyl methyl ether, carboxylated polymethylene, polyvinylpyrrolidone, poly(N-alkyl)-substituted acrylamide, poly(N-vinylalkylamide), polyethylene oxide, polyester, polyether, and any combination thereof; Element 3: The biodegradable coating comprises a polymer selected from the group consisting of polystyrene, polyethylene, polypropylene, etc., and any combination thereof; Element 4: The stimulant includes exposure to an aqueous fluid, exposure to an oily fluid, an increase in temperature, an externally applied electric field, a change in pH, a change in ion concentration, exposure to light, or any combination thereof; Element 5: The biodegradable coating covers 25% to 100% of the surface area of ​​the aggregated particles. Element 6: wherein the degradable coating comprises 10% or less of the diameter of the self-aggregating particles having the degradable coating; Element 7: wherein the degradable coating comprises at least two degradable materials that degrade in response to different stimuli; Element 8: wherein the degradable coating comprises multiple layers, wherein at least two of the multiple layers are formed of different degradable materials that degrade in response to different stimuli; Element 9: wherein the mechanical interaction utilizes one or more physical features of the particles, the one or more physical features being selected from the group consisting of: hook-shaped protrusions, protrusion-cavity pairs, complementary particle shapes, and any combination thereof; Element 10: wherein the plurality of particles comprises a first particle shape and a second particle shape, the first particle shape and the second particle shape being complementary to achieve the mechanical interaction; Element 11: wherein the chemical interaction is a hydrophobic interaction or capillary interaction between the plurality of self-aggregating particles; and Element 12: wherein the average diameter of the plurality of self-aggregating particles is from 0.1 mm to 2 mm, and wherein the average diameter of the plurality of aggregated particles is 3 mm or greater.Examples of combinations include: combining element 1 with one or more of elements 2-12; combining element 2 with one or more of elements 3-12; combining element 3 with one or more of elements 4-12; combining element 4 with one or more of elements 5-12; combining element 5 with one or more of elements 6-12; combining element 6 with one or more of elements 7-12; combining element 7 with one or more of elements 8-12; combining element 8 with one or more of elements 9-12; combining element 9 with one or more of elements 10-12; and combining two or more of elements 10-12.

[0053] The second exemplary embodiment disclosed in this specification includes: a drilling fluid comprising: a base fluid; and a plurality of self-aggregating particles having a degradable coating, wherein the self-aggregating particles are capable of combining into a plurality of aggregated particles via mechanical interaction, electrical interaction, magnetic interaction, chemical interaction, or any combination thereof. The second exemplary embodiment may have one or more of the following elements: Element 13: wherein the degradable coating comprises a polymer selected from the group consisting of gelatin, polyvinyl alcohol, polyethylene glycol, polysaccharides, carboxymethyl cellulose, polyacrylamide, polyacrylic acid, polyamine, polyethyleneimine, polyvinyl methyl ether, carboxylated polymethylene, polyvinylpyrrolidone, poly(N-alkyl)-substituted acrylamide, poly(N-vinylalkylamide), polyethylene oxide, polyester, polyether, and any combination thereof; Element 14: wherein the degradable coating comprises a polymer selected from the group consisting of polystyrene, polyethylene, polypropylene, etc., and any combination thereof; Element 15: wherein the degradable coating covers 25% to 100% of the surface area of ​​the self-aggregating particles; Element 16: wherein the degradable coating accounts for 10% or less of the diameter of the self-aggregating particles having the degradable coating; Element 17: wherein the degradable coating comprises at least two degradable materials that degrade in response to different stimuli; Element 18 Element 19: The biodegradable coating comprises multiple layers, wherein at least two of the multiple layers are formed of different biodegradable materials that degrade in response to different stimuli; Element 20: The mechanical interaction utilizes one or more physical features of the particles, the one or more physical features being selected from the group consisting of: hook-like protrusions, protrusion-cavity pairs, complementary particle shapes, and any combination thereof; Element 21: The plurality of particles comprises a first particle shape and a second particle shape, the first particle shape and the second particle shape being complementary to achieve the mechanical interaction; Element 22: The chemical interaction is a hydrophobic interaction or capillary interaction between the plurality of self-aggregating particles; Element 23: The plurality of self-aggregating particles have an average diameter of 0.1 mm to 2 mm, and the plurality of aggregated particles have an average diameter of 3 mm or greater; Element 24: The plurality of self-aggregating particles are present in the drilling fluid at 0.1 wt% to 10 wt% based on the weight of the base fluid; and Element 25: The drilling fluid also includes additives as stimuli. Examples of combinations include: combining element 13 with one or more of elements 14-24; combining element 14 with one or more of elements 15-24; combining element 15 with one or more of elements 16-24; combining element 16 with one or more of elements 17-24; combining element 17 with one or more of elements 18-24; combining element 18 with one or more of elements 19-24; combining element 19 with one or more of elements 20-24; and combining two or more of elements 20-24.

[0054] The third exemplary embodiment disclosed in this specification includes: a composition comprising: a plurality of self-aggregating particles having a biodegradable coating, wherein the self-aggregating particles are capable of combining into a plurality of aggregated particles via mechanical interaction, electrical interaction, magnetic interaction, chemical interaction, or any combination thereof. A third exemplary embodiment may have one or more of the following elements: Element 25: wherein the degradable coating comprises a polymer selected from the group consisting of gelatin, polyvinyl alcohol, polyethylene glycol, polysaccharides, carboxymethyl cellulose, polyacrylamide, polyacrylic acid, polyamine, polyethyleneimine, polyvinyl methyl ether, carboxylated polymethylene, polyvinylpyrrolidone, poly(N-alkyl)-substituted acrylamide, poly(N-vinylalkylamide), polyethylene oxide, polyester, polyether, and any combination thereof; Element 26: wherein the degradable coating comprises a polymer selected from the group consisting of polystyrene, polyethylene, polypropylene, etc., and any combination thereof; Element 27: wherein the degradable coating covers 25% to 100% of the surface area of ​​the self-aggregating particles; Element 28: wherein the degradable coating accounts for 10% or less of the diameter of the self-aggregating particles having the degradable coating; Element 29: wherein the degradable coating comprises at least two substances that degrade in response to different stimuli. Degradable material; Element 30: wherein the degradable coating comprises multiple layers, wherein at least two of the multiple layers are formed of different degradable materials that degrade in response to different stimuli; Element 31: wherein the mechanical interaction utilizes one or more physical features of the particles, the one or more physical features being selected from the group consisting of: hook-like protrusions, protrusion-cavity pairs, complementary particle shapes, and any combination thereof; Element 32: wherein the plurality of particles comprise a first particle shape and a second particle shape, the first particle shape and the second particle shape being complementary to achieve the mechanical interaction; Element 33: wherein the chemical interaction is a hydrophobic interaction or capillary interaction between the plurality of self-aggregating particles; Element 34: wherein the plurality of self-aggregating particles have an average diameter of 0.1 mm to 2 mm, and wherein the plurality of aggregated particles have an average diameter of 3 mm or greater; and Element 35: wherein the plurality of self-aggregating particles are present in the drilling fluid at a weight of 0.1 wt% to 10 wt% based on the base fluid. Examples of combinations include: element 25 combined with one or more of elements 26-35; element 26 combined with one or more of elements 27-35; element 27 combined with one or more of elements 28-35; element 28 combined with one or more of elements 29-35; element 29 combined with one or more of elements 30-35; element 30 combined with one or more of elements 31-35; element 31 combined with one or more of elements 32-35; and two or more of elements 32-35 combined.

[0055] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, as used in this disclosure, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to also include the plural forms. It should also be understood that when the terms “comprising,” “containing,” and / or “including,” and variations thereof are used in this specification, they specify the presence of the stated feature, integral, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, and / or components.

[0056] The directional terminology used in this disclosure is for convention and reference purposes only and should not be construed as limiting. However, it should be understood that these terms may be used by reference to an operator or user. Therefore, no limitation is implied or inferred. Furthermore, the use of ordinal numbers (e.g., first, second, third, etc.) is for distinction rather than for counting. For example, the use of “third” does not necessarily imply a corresponding “first” or “second”. In addition, if used in this disclosure, the terms “coupled” or “coupled to” or “connected” or “attached” or “attached to” may indicate the establishment of a direct or indirect connection, and are not limited to either, unless so expressly stated.

[0057] While several exemplary embodiments have been described in this disclosure, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from the spirit and scope of the invention. Furthermore, those skilled in the art will understand that many modifications can be made to adapt specific instruments, situations, or materials to embodiments of this disclosure without departing from the essential scope of the invention. Therefore, the invention is not limited to the specific embodiments disclosed or the best mode for carrying out the invention, but rather will include all embodiments falling within the scope of the appended claims. Furthermore, any reference in the appended claims to a device or system or a component of a device or system adapted to, arranged to, be enabled to, be configured to, be operable to, or be able to perform a specific function covers that device, system, or component, regardless of whether the device, system, or component or the specific function is activated, turned on, or unlocked, provided that the device, system, or component is so adapted, arranged, enabled, configured to, be operable to, or be able to perform.

Claims

1. A composition comprising: Multiple self-aggregating particles having a biodegradable coating, wherein the self-aggregating particles can combine into multiple aggregated particles via mechanical interaction, electrical interaction, magnetic interaction, chemical interaction, or any combination thereof.

2. A method comprising: Drilling at least a portion of a wellbore through underground formations using drilling fluid, said drilling fluid comprising: Base liquid; Includes a plurality of self-aggregating particles of the composition according to claim 1; and The plurality of particles are exposed to a stimulus that causes a reduction in the thickness of the degradable coating, thereby exposing the binding portions of the self-aggregating particles and allowing the plurality of self-aggregating particles to combine into a plurality of aggregated particles.

3. The method according to claim 2, further comprising: An additive is introduced into the wellbore, wherein the additive is the stimulant.

4. The method according to claims 2 to 3, wherein, The biodegradable coating comprises a polymer selected from the group consisting of: gelatin, polyvinyl alcohol, polyethylene glycol, polysaccharides, carboxymethyl cellulose, polyacrylamide, polyacrylic acid, polyamine, polyethyleneimine, polyvinyl methyl ether, carboxylated polymethylene, polyvinylpyrrolidone, poly(N-alkyl)-substituted acrylamide, poly(N-vinylalkylamide), polyethylene oxide, polyester, polyether, and any combination thereof.

5. The method according to claims 2 to 4, wherein, The biodegradable coating comprises a polymer selected from the group consisting of polystyrene, polyethylene, polypropylene, and any combination thereof.

6. The method according to claims 2 to 5, wherein, The stimuli include exposure to aqueous fluids, exposure to oily fluids, increased temperature, externally applied electric fields, changes in pH, changes in ion concentration, exposure to light, or any combination thereof.

7. The method according to claims 2 to 6, wherein, The biodegradable coating covers 25% to 100% of the surface area of ​​the self-aggregating particles.

8. The method according to claims 2 to 7, wherein, The biodegradable coating comprises 10% or less of the diameter of the self-aggregating particles having the biodegradable coating.

9. The method according to claims 2 to 8, wherein, The biodegradable coating comprises at least two biodegradable materials that degrade in response to different stimuli.

10. The method according to claims 2 to 9, wherein, The biodegradable coating comprises multiple layers, at least two of which are formed of different biodegradable materials that degrade in response to different stimuli.

11. The method according to claim 2, wherein, The mechanical interaction utilizes one or more physical features of the particles, which are selected from the group consisting of hook-shaped protrusions, protrusion-cavity pairs, complementary particle shapes, and any combination thereof.

12. The method according to claim 2, wherein, The plurality of particles include a first particle shape and a second particle shape, the first particle shape and the second particle shape being complementary to achieve the mechanical interaction.

13. The method according to claim 2, wherein, The chemical interaction is a hydrophobic interaction or capillary interaction between the plurality of self-aggregating particles.

14. The method according to claim 2, wherein, The plurality of self-aggregating particles have an average diameter of 0.1 mm to 2 mm, and wherein the plurality of aggregated particles have an average diameter of 3 mm or greater.

15. A drilling fluid, comprising: Base liquid; as well as A plurality of self-aggregating particles having the composition according to claim 1.

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