Emulsifiers for drilling operations

Abstract

Provided is a composition including an oleaginous continuous phase, a non-oleaginous discontinuous phase, and an acylated polyolefin emulsifier, wherein each molecule of the acylated polyolefin emulsifier includes an oil-soluble polyolefin portion and, on average across all molecules of the acylated polyolefin emulsifier, at least one acyl group attached to the oil-soluble polyolefin portion, wherein the oil-soluble polyolefin portion has a number-average molecular weight of 450 to 3000 Daltons, and wherein at least 25 mol% of all the at least one acyl groups present in the acylated polyolefin emulsifier contain at least one of an ester group, a carboxylic acid group, or a carboxylate salt.

Description

EMULSIFIERS FOR DRILLING OPERATIONS

[0001] The disclosed technology relates to emulsifiers and compositions including the emulsifiers, which may be used in oilfield drilling applications.

[0002] During wellbore operations, various fluids may be used in the well for a variety of functions. The fluids may be circulated through a bore hole, which may subsequently flow upward through the wellbore to the surface. During this circulation, the drilling fluid may remove drill cuttings from the bottom of the hole to the surface, to suspend cuttings and weighting material when circulation is interrupted, to control subsurface pressures, to maintain the integrity of the wellbore until the well section is cased and cemented, to isolate the fluids from the formation by providing sufficient hydrostatic pressure to prevent the ingress of formation fluids into the wellbore, to cool and lubricate the drill string and bit, and / or to maximize penetration rate.

[0003] Wellbore fluids may take the form of oil-based fluids, such as invert emulsion muds. The components of the invert emulsion fluids generally include an oleaginous liquid, such as hydrocarbon oil, which serves as a continuous phase, a non-oleaginous liquid, such as water or brine solution, which serves as a discontinuous phase, and at least one emulsifier. Emulsifiers may be used to lower the interfacial tension of the liquids so that the non-oleaginous liquid may form a stable dispersion of fine droplets in the oleaginous liquid. Additionally, such invert emulsion fluids may contain one or more weighting agents, surfactants, viscosifiers, fluid loss control agents, and / or bridging agents.

[0004] Invert emulsion drilling fluid systems may be formulated using primary and secondary emulsifiers. Primary emulsifiers are generally used to reduce interfacial tension between the liquid phases and hence make the internal phase dispersible in the continuous phase, while secondary emulsifiers consolidate stability of the dispersed phase and / or stability of the emulsion. In inverted emulsion systems, stability is usually a significant issue. Stability of such systems is generally determined by measuring electrical stability (“ES”). The voltage required to destabilize the dispersed phase is recorded as the ES value. The higher the ES value, the more stable the emulsion. Not only is a high ES needed for invert emulsion drilling fluid systems, but the emulsifiers also should maintain rheological properties of the systems to improve functionality.

[0005] The disclosed technology provides emulsifiers which can be used as primary and / or secondary emulsifiers in drilling fluid compositions and, at least in certain embodiments, may provide more efficient emulsifiers and / or eliminate the need to use separate emulsifier compositions to achieve the objectives previously achieved by using separate primary and secondary emulsifiers.

[0006] The subject matter disclosed herein provides a composition comprising an oleaginous continuous phase, a non-oleaginous discontinuous phase, and an acylated polyolefin emulsifier. In certain embodiments, each molecule of the acylated polyolefin emulsifier consists of an oil-soluble polyolefin portion and, on average across all molecules of the acylated polyolefin emulsifier, at least one acyl group attached to the oil-soluble polyolefin portion. In certain embodiments, the oil-soluble polyolefin portion has a number-average molecular weight of 450 to 3000 Daltons. In certain embodiments, at least 25 mol% of all the at least one acyl groups present in the acylated polyolefin emulsifier contain at least one of an ester group, a carboxylic acid group, or a carboxylate salt. The composition may be used as a drilling fluid in drilling applications, such as in wellbore drilling operations.

[0007] The following embodiments of the present subject matter are contemplated:

[0008] 1. A composition comprising an oleaginous continuous phase, a non- oleaginous discontinuous phase, and an acylated polyolefin emulsifier, wherein each molecule of the acylated polyolefin emulsifier consists of an oil-soluble polyolefin portion and, on average across all molecules of the acylated polyolefin emulsifier, at least one acyl group attached to the oil-soluble polyolefin portion, wherein the oil-soluble polyolefin portion has a number-average molecular weight of 450 to 3000 Daltons, and wherein at least 25 mol% of all the at least one acyl groups present in the acylated polyolefin emulsifier contain at least one of an ester group, a carboxylic acid group, or a carboxylate salt.

[0009] 2. The composition of embodiment 1, wherein the acylated polyolefin emulsifier comprises at least one polymer of branched or linear 1 -olefin monomers having from 4 to 8 carbon atoms.

[0010] 3 The composition of either embodiment 1 or embodiment 2, wherein the acylated polyolefin emulsifier comprises at least one polymer of branched or linear monomers having from 4 to 6 carbon atoms, and wherein at least 90 mol percent of the monomers are 1- butene and / or isobutylene.

[0011] 4 The composition of any one of embodiments 1 to 3, wherein ester groups are present in the acylated polyolefin, and the ester groups comprise at least one hydrocarbyl group having from 2 to 18 carbon atoms.

[0012] 5. The composition of embodiment 4, wherein the at least one hydrocarbyl group further comprises at least one additional heteroatom comprising at least one of nitrogen or oxygen.

[0013] 6. The composition of either embodiment 4 or embodiment 5, wherein the ester group comprises a hydrocarbyl group substituted with at least one secondary or tertiary nitrogen group.

[0014] 7. The composition of any one of embodiments 1 to 6, wherein the acylated polyolefin emulsifier has a total base number of at least 20 mg KOH / g.

[0015] 8. The composition of any one of embodiments 1 to 7, wherein the acylated polyolefin emulsifier has a total acid number of at least 10 mg KOH / g.

[0016] 9. The composition of any one of embodiments 1 to 8, wherein the acylated polyolefin emulsifier has a total base number and a total acid number, wherein the total acid number is at least 50% of the value of the total base number.

[0017] 10. The composition of any one of embodiments 1 to 9, wherein each molecule of the acylated polyolefin emulsifier consists of an oil-soluble polyolefin portion and, on average across all molecules of the acylated polyolefin emulsifier, at least two acyl groups attached to the oil-soluble polyolefin portion, wherein, on average across all molecules of the acylated polyolefin emulsifier, at least one of the at least two acyl groups present in the acylated polyolefin emulsifier is an ester group, and wherein the ester group is an ester of an alkanolamine and the alkanolamine comprises a tertiary or secondary amine.

[0018] 11. The composition of embodiment 10, wherein the alkanolamine comprises at least one of diethanolamine, diethyl ethanolamine, triethanolamine, monomethyl ethanolamine, methyl diethanolamine, or aminoethyl ethanolamine.

[0019] 12. The composition of any one of embodiments 1 to 11, wherein the acylated polyolefin emulsifier is present in an amount of from 0.1 to 15 weight percent, based on the total weight of the composition.

[0020] 13. The composition of any one of embodiments 1 to 12, wherein the composition further comprises a viscosifier.

[0021] 14. The composition of embodiment 13, wherein the viscosifier comprises at least one organophilic clay, wherein the organophilic clay comprises at least one of attapulgite, sepiolite, or bentonite.

[0022] 15. The composition of either embodiment 13 or embodiment 14, wherein the viscosifier is present in the composition in an amount from 0.1 to 10 weight percent, based on the total weight of the composition.

[0023] 16. The composition of any one of embodiments 1 to 15, wherein the composition further comprises at least one weighting agent.

[0024] 17. The composition of embodiment 16, wherein the weighting agent comprises at least one of hematite, magnetite, iron oxide, ilmenite, barite, siderite, celestite, dolomite, calcite, manganese oxide, or halite.

[0025] 18. The composition of either embodiment 16 or embodiment 17, wherein the weighting agent is present in the composition in an amount such that the density of the composition is up to 22 pounds per gallon.

[0026] 19. The composition of any one of embodiments 16 to 18, wherein the weighting agent is present in the composition in an amount of from 5 to 30 pounds per gallon, based on the total volume of the composition.

[0027] 20. The composition of any one of embodiments 1 to 19, wherein the composition further comprises lime.

[0028] 21. The composition of embodiment 20, wherein the lime is present in the composition in an amount from 0.1 to 2 weight percent, based on the total weight of the composition.

[0029] Various features and embodiments of the present subject matter will be described below by way of non-limiting illustration.

[0030] As used herein, the term “condensation product” is intended to encompass esters, amides, imides and other such materials that may be prepared by a condensation reaction of an acid or a reactive equivalent of an acid (e.g., an acid halide, anhydride, or ester) with an alcohol or amine, irrespective of whether a condensation reaction is actually performed to lead directly to the product. Thus, for example, a particular ester may be prepared by a transesterification reaction rather than directly by a condensation reaction. The resulting product is still considered a condensation product.

[0031] The amount of each chemical component described herein is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, that is, on an active chemical basis, unless otherwise indicated. Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade.

[0032] As used herein, the term “hydrocarbyl” refers to a group having a carbon atom directly attached to the remainder of the molecule, where the group includes at least carbon and hydrogen atoms. If the hydrocarbyl group comprises more than one carbon atom, then those carbons need not necessarily be linked to each other. For example, at least two of the carbons may be linked via a suitable element or group. In various embodiments, the term “hydrocarbyl” refers to a group having a carbon atom directly attached to the remainder of the molecule, where the group consists of carbon, hydrogen, optionally one or more heteroatoms provided the heteroatoms do not alter the predominantly hydrocarbon nature of the substituent. The heteroatom may to link at least two of the carbons in the hydrocarbyl group, and optionally no more than two non-hydrocarbon substituents. Suitable heteroatoms will be apparent to those skilled in the art and include, for instance, sulphur, nitrogen, oxygen, phosphorus and silicon. Where the hydrocarbyl contains heteroatoms, optionally, no more than two heteroatoms will be present for every ten carbon atoms in the hydrocarbyl group. Suitable non-hydrocarbon substituents will also be apparent to those skilled in the art and include, for instance, halo, hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulphoxy.

[0033] Examples of hydrocarbyls within the context of the present technology therefore include: (i) hydrocarbon groups selected from aliphatic (e.g. alkyl or alkenyl), alicyclic (e.g. cycloalkyl, cycloalkenyl, cycloalkadienyl), and aromatic groups; (ii) substituted hydrocarbon groups, selected from hydrocarbon groups defined in (i) substituted with no more than two non- hydrocarbon substituents and / or one or more hydrocarbon substituents, the non-hydrocarbon substituents being selected from the group consisting of halo, hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulphoxy; and / or (iii) hetero-containing hydrocarbon groups, selected from hydrocarbon groups defined in (i) containing one or more heteroatom in the ring or chain, provided that the group has no more than two heteroatoms present for every ten carbon atoms in the group, the heteroatoms being selected from sulphur, nitrogen, oxygen, phosphorusand silicon. The hetero-containing hydrocarbon groups may be substituted with no more than two non-hydrocarbon substituents and / or one or more hydrocarbon substituents. In certain embodiments, the term “hydrocarbyl” refers to a group having a carbon atom directly attached to the remainder of the molecule, where the group consists of carbon and hydrogen atoms.

[0034] It is known that some of the materials described herein may interact in the final formulation, so that the components of the final formulation may be different from those that are initially added. For instance, metal ions (of, e.g., a detergent) may migrate to other acidic or anionic sites of other molecules. The products formed thereby, including the products formed upon employing the composition of the present subject matter in its intended use, may not be susceptible of easy description. Nevertheless, all such modifications and reaction products are included within the scope of the present subject matter; the present subject matter encompasses the composition prepared by admixing the components described herein.

[0035] As used herein, the indefinite article “a” / “an” is intended to mean one or more than one. As used herein, the phrase “at least one” means one or more than one of the following terms. Thus, “a” / “an” and “at least one” may be used interchangeably. For example “at least one of A, B or C” means that just one of A, B or C may be included, and any mixture of two or more of A, B and C may be included, in alternative embodiments.

[0036] As used herein, the term “substantially” means that a value of a given quantity is within ±10% of the stated value. In other embodiments, the value is within ±5% of the stated value. In other embodiments, the value is within ±2.5% of the stated value. In other embodiments, the value is within ±1% of the stated value.

[0037] As used herein, the term “substantially free of’ means that a component does not include any intentional addition of the material which the component is “substantially free of’. For example, the component may include a material which the component is “substantially free of’ at no more than impurity levels, which may be the result of incomplete chemical reactions and / or unintended / undesired (but perhaps unavoidable) reaction products.

[0038] As used herein, the transitional term “comprising,” which is synonymous with “including,” “containing,” or “characterized by,” is inclusive or open-ended and does not exclude additional, un-recited elements or method steps. However, in each recitation of “comprising” herein, it is intended that the term also encompass, as alternative embodiments, the phrases “consisting essentially of’ and “consisting of,” where “consisting of’ excludes anyelement or step not specified and “consisting essentially of’ permits the inclusion of additional un-recited elements or steps that do not materially affect the essential or basic and novel characteristics of the composition or method under consideration.

[0039] Provided is a composition comprising an oleaginous continuous phase, a non- oleaginous discontinuous phase, and an acylated polyolefin emulsifier, wherein each molecule of the acylated polyolefin emulsifier consists of an oil-soluble polyolefin portion and, on average across all molecules of the acylated polyolefin emulsifier, at least one acyl group attached to the oil-soluble polyolefin portion, wherein the oil-soluble polyolefin portion has a number-average molecular weight of 450 to 3000 Daltons, and wherein at least 25 mol% of all the at least one acyl groups present in the acylated polyolefin emulsifier contain at least one of an ester group, a carboxylic acid group, or a carboxylate salt. In the context of the previous sentence, “consists of’ means that the acylated polyolefin emulsifier does not include anything other than what it is described as, in the ordinary interpretation of “consists of’ under the laws and / or case law of the United States. However, this does not exclude the possibility of the composition including other emulsifiers, or any other ingredients.

[0040] In certain embodiments, the oil-soluble polyolefin portion has a number-average molecular weight of 450 to 3000 (such as from 500 to 3000, from 550 to 3000, from 600 to 3000, from 700 to 3000, from 800 to 3000, from 900 to 3000, from 1000 to 3000, from 1200 to 3000, from 1500 to 3000, from 450 to 2500, from 500 to 2500, from 550 to 2500, from 600 to 2500, from 700 to 2500, from 800 to 2500, from 900 to 2500, from 1000 to 2500, from 1200 to 2500, from 1500 to 2500, from 450 to 2000, from 500 to 2000, from 550 to 2000, from 600 to 2000, from 700 to 2000, from 800 to 2000, from 900 to 2000, from 1000 to 2000, from 1200 to 2000, from 1500 to 2000, from 450 to 1500, from 500 to 1500, from 550 to 1500, from 600 to 1500, from 700 to 1500, from 800 to 1500, from 900 to 1500, from 1000 to 1500, or from 1200 to 1500) Daltons.

[0041] In certain embodiments, at least 25 (such as at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, or at least 75) mol% of all the at least one acyl groups present in the acylated polyolefin emulsifier contain at least one of an ester group, a carboxylic acid group, or a carboxylate salt.

[0042] In certain embodiments, the acylated polyolefin emulsifier comprises at least one polymer of branched or linear 1 -olefin monomers having from 4 to 8 (such as from 4 to 7, from4 to 6, from 4 to 5, from 5 to 8, from 5 to 7, from 5 to 6, from 6 to 8, from 6 to 7, from 7 to 8, or 4, 5, 6, 7, or 8) carbon atoms. In the context of the previous sentence, “comprises” means that that the acylated polyolefin emulsifier includes the described material, and may also include any other material which falls within the above description of what the acylated polyolefin emulsifier consists of.

[0043] In certain embodiments, the acylated polyolefin emulsifier comprises at least one polymer of branched or linear monomers having from 4 to 6 (such as from 4 to 5, from 5 to 6, or 4, 5, or 6) carbon atoms, and wherein at least 90 (such as at least 91, at least 92, at least 93, at least 94, at least 95, at least 96, at least 97, at least 98, or at least 99) mol percent of the monomers are 1 -butene and / or isobutylene. In the context of the previous sentence, “comprises” means that that the acylated polyolefin emulsifier includes the described material, and may also include any other material which falls within the above description of what the acylated polyolefin emulsifier consists of.

[0044] In certain embodiments, ester groups are present in the acylated polyolefin, and the ester groups comprise at least one hydrocarbyl group having from 2 to 18 (such as from 4 to 18, from 6 to 18, from 8 to 18, from 10 to 18, from 12 to 18, from 14 to 18, from 16 to 18, from 2 to 16, from 4 to 16, from 6 to 16, from 8 to 16, from 10 to 16, from 12 to 16, from 14 to 16, from 2 to 14, from 4 to 14, from 6 to 14, from 8 to 14, from 10 to 14, from 12 to 14, from 2 to 12, from 4 to 12, from 6 to 12, from 8 to 12, from 10 to 12, from 2 to 10, from 4 to 10, from 6 to 10, from 8 to 10, from 2 to 8, from 4 to 8, from 6 to 8, from 2 to 6, from 4 to 6, from 2 to 4, or 2, 4, 6, 8, 10, 12, 14, 16, or 18) carbon atoms.

[0045] In certain embodiments, the at least one hydrocarbyl group further comprises at least one additional heteroatom comprising at least one of nitrogen or oxygen.

[0046] In certain embodiments, the ester group comprises a hydrocarbyl group substituted with at least one secondary or tertiary nitrogen group.

[0047] In certain embodiments, the acylated polyolefin emulsifier has a total base number of at least 20 mg KOH / g. In certain embodiments, the acylated polyolefin emulsifier has a total acid number of at least 10 mg KOH / g. In certain embodiments, the acylated polyolefin emulsifier has a total base number and a total acid number, wherein the total acid number is at least 50% (such as at least 100%) of the value of the total base number.

[0048] In certain embodiments, each molecule of the acylated polyolefin emulsifier consists of an oil-soluble polyolefin portion and, on average across all molecules of the acylated polyolefin emulsifier, at least two acyl groups attached to the oil-soluble polyolefin portion, wherein, on average across all molecules of the acylated polyolefin emulsifier, at least one of the at least two acyl groups present in the acylated polyolefin emulsifier is an ester group, and wherein the ester group is an ester of an alkanolamine and the alkanolamine comprises a tertiary or secondary amine. In certain embodiments, the alkanolamine comprises at least one of diethanolamine, diethyl ethanolamine, triethanolamine, monomethyl ethanolamine, methyl diethanolamine, or aminoethyl ethanolamine.

[0049] In certain embodiments, the acylated polyolefin emulsifier is present in an amount of from 0.1 to 15 (such as from 0.5 to 15, from 1 to 15, from 2 to 15, from 3 to 15, from 4 to 15, from 5 to 15, from 0.1 to 12, from 0.5 to 12, from 1 to 12, from 2 to 12, from 3 to 12, from 4 to 12, from 5 to 12, from 0.1 to 10, from 0.5 to 10, from 1 to 10, from 2 to 10, from 3 to 10, from 4 to 10, or from 5 to 10) weight percent, based on the total weight of the composition. As described above, the acylated polyolefin emulsifier may be used as either or both of a primary emulsifier or a secondary emulsifier. When used as a primary emulsifier or a secondary emulsifier, the acylated polyolefin emulsifier may be used in an amount which is generally understood as acceptable by those of ordinary skill in the art in such situations. However, it is also possible that the acylated polyolefin emulsifier may be used as the only emulsifier in the composition, such that an additional primary or secondary emulsifier is not required; in these instances, use of the acylated polyolefin emulsifier in amounts similar to those generally used for primary emulsifiers may be sufficient, but in any event a person of ordinary skill in the art would be able to determine the appropriate amount for a particular composition by routine experimentation.

[0050] In certain embodiments, the oleaginous continuous phase comprises at least one of natural oils, synthetic oils, diesel oil, or mineral oil. In certain embodiments, the synthetic oils may comprise at least one of esters, olefins, or paraffins. In this context, esters are synthetic oils which may be derived from the reaction of an alcohol and an organic acid, and may include methyl ester and / or phthalate ester. In this context, olefins are synthetic oils, such as polyalphaolefins, which may be derived from the polymerization of alpha-olefins. In thiscontext, paraffins are synthetic oils which may be synthesized by isomerizing liner alpha- olefins.

[0051] In certain embodiments, the non-oleaginous discontinuous phase comprises at least one of water, sea water, or brine, optionally further comprising at least one water-soluble organic compound. In this context, the water may be fresh water and / or produced water. In certain embodiments, the non-oleaginous discontinuous phase comprises a brine, wherein the brine comprises water and at least one salt, wherein the at least one salt comprises sodium, calcium, aluminum, magnesium, potassium, strontium, and / or lithium salts of chlorides, bromides, carbonates, iodides, chlorates, bromates, formates, nitrates, oxides, sulfates, silicates, phosphates, and / or fluorides.

[0052] In certain embodiments, the ratio of the oleaginous continuous phase to the non- oleaginous discontinuous phase is from 40:60 to 95:5.

[0053] In certain embodiments, the composition further comprises a viscosifier, optionally wherein the viscosifier comprises at least one organophilic clay. In certain embodiments, the viscosifier comprises at least one organophilic clay, wherein the organophilic clay comprises at least one of attapulgite, sepiolite, or bentonite. In certain embodiments, the viscosifier is present in the composition in an amount from 0.1 to 10 (such as from 0.5 to 10, from 1 to 10, from 2 to 10, from 3 to 10, from 4 to 10, from 5 to 10, from 0.1 to 8, from 0.5 to 8, from 1 to 8, from 2 to 8, from 3 to 8, from 4 to 8, from 5 to 8, from 0.1 to 6, from 0.5 to 6, from 1 to 6, from 2 to 6, from 3 to 6, from 4 to 6, or from 5 to 6) weight percent, based on the total weight of the composition.

[0054] In certain embodiments, the composition further comprises at least one weighting agent. In certain embodiments, the weighting agent comprises at least one of hematite, magnetite, iron oxide, ilmenite, barite, siderite, celestite, dolomite, calcite, manganese oxide, or halite. In certain embodiments, the weighting agent is present in the composition in an amount such that the density of the composition is up to 22 pounds per gallon. In certain embodiments, the weighting agent is present in the composition in an amount of from 5 to 30 pounds per gallon, based on the total volume of the composition.

[0055] In certain embodiments, the composition further comprises lime. In certain embodiments, the lime is present in the composition in an amount from 0.1 to 2 (such as from0.1 to 1 .5, from 0.1 to 1, from 0.2 to 2, from 0.2 to 1 .5, or from 0.2 to 1) weight percent, based on the total weight of the composition.

[0056] As described above, the compositions described herein may be used as wellbore fluids in drilling and / or mining (or similar) operations. Wellbore fluids in accordance with the present disclosure may be prepared as an emulsion having a discontinuous aqueous phase within a continuous oleaginous phase. Base fluids useful for preparing emulsions in accordance with the present disclosure may include at least one of fresh water, sea water, brine, mixtures of water and water-soluble organic compounds, and mixtures thereof. The aqueous fluid may be a brine, which may include seawater, aqueous solutions wherein the salt concentration is less than that of sea water, or aqueous solutions wherein the salt concentration is greater than that of sea water. Salts that may be found in seawater include, but are not limited to, sodium, calcium, aluminum, magnesium, potassium, strontium, and lithium salts of chlorides, bromides, carbonates, iodides, chlorates, bromates, formates, nitrates, oxides, sulfates, silicates, phosphates and fluorides. Salts that may be incorporated in a brine include any one or more of those present in natural seawater or any other organic or inorganic dissolved salts. Suitable oleaginous or oil-based fluids which may be used to formulate emulsions may include a natural or synthetic oil and the oleaginous fluid may be selected from the group including: diesel oil; mineral oil; a synthetic oil, such as hydrogenated and unhydrogenated olefins including polyalpha olefins, linear and branch olefins and the like, polydiorganosiloxanes, siloxanes, or organosiloxanes, esters of fatty acids, specifically straight chain, branched and cyclical alkyl ethers of fatty acids, mixtures thereof and similar compounds known to one of skill in the art; and mixtures thereof.

[0057] The illustrative wellbore fluids may also contain wellbore fluid additives such as emulsifiers, wetting agents, organophilic clays, viscosifiers, bridging agents, fluid loss control agents, alkalinity control agents, and corrosion inhibitors, which may be added to the compositions disclosed herein so as to impart additional functional properties.

[0058] Wetting agents that may be suitable for use in combination with the emulsifiers described herein include, but are not limited to, crude tall oil, oxidized crude tall oil, surfactants, organic phosphate esters, ether carboxylic acids, fatty amines, amidoamines, modified imidazolines and amidoamines, fatty acid amidoamines (including dry fatty acid amidoamines) and salts thereof, ethoxylates, branched or linear primary alcohol ethoxylates, secondaryalcohol ethoxylates, branched decyltridecyl alcohol ethoxylates, branched or linear alkylphenol ethoxylates, branched or linear alkyl amine ethoxylates, alkyl ether amine ethoxylates, linear alcohol alkoxylates, alkyl aromatic sulfates and sulfonates such as alkyl benzene sulfonates, calcium dodecylbenzenesulphonate, and the like, and combinations or derivatives of these. VERSAWET™ and VERSACOAT™, NOVAMUL™, FAZEMUL™, FAZEWET™, MEGAMUL™, SUREMUL™, ONEMUL™, ACT1MUL RD™, and MUL-XT™ are nonlimiting examples of commercially-available wetting agents manufactured and distributed by M-I, L.L.C., which may be used in the illustrative wellbore fluids. Other suitable surfactants that are commercially available include SIL WET™ series of emulsifiers such as L-77, L-7001, L7605 and L-7622, which are distributed by Momentive.

[0059] The wetting agents may be carboxylic acid-based wetting agents such as, for example, di carboxylic fatty acids, dimer acids, or dimers of fatty acids. Dicarboxylic fatty acids have the general formula HOOC — R — COOH, wherein R is an alkyl or alkenyl group containing from 10 to 50 carbon atoms, and in particular embodiments from 20 to 40 carbon atoms. Wetting agents may include the dimerization products of unsaturated dicarboxylic fatty acids, for example, such as products prepared by dimerization of unsaturated fatty acids containing from 8 to about 18 carbon atoms, including 9-dodecenoic, 9-tetradecenoic, 9- octadecenoic, octadecatetranoic acids, and the like.

[0060] Organophilic clays, such as amine-treated clays, may be useful as viscosifiers in the illustrative wellbore fluids. Other viscosifiers and gellants, such as oil soluble polymers, polyamide resins, polycarboxylic acids, and soaps may also be used. Clays such as attapulgite, sepiolite, bentonite, and the like may also be used as viscosifiers. The amount of viscosifier used in the compositions may vary depending on downhole conditions, as understood by those skilled in the art. However, normally about 0.1% to 6% by weight range may be sufficient for most applications. VG-69™, VG-SUPREME™, VG-HT™, and VG-PLUS™ are organoclay products commercially available from M-I, L.L.C. (Houston, Tex.), and VERSA-HRP™ is a polyamide resin material available from M-I L.L.C. (Houston, Tex.) that may be used in the illustrative wellbore fluids.

[0061] Fluid loss control agents may act by coating the walls of a well. Suitable fluid loss control agents may include, but are not limited to, modified lignites, asphaltic compounds, gilsonite, organophilic humates, or tannins prepared by reacting humic acid or tannic acid withamides or polyalkylene polyamines, amine-treated tannins such as ONE-TROL-HT™, and latex polymers. The fluid loss control agent may include one or more of VERSATROL™, VERSALIG™, ECOTROL™ family of products, ONETROL-HT™, EMI 789, and NOVATECH™ F, which are all commercially available from MI SWACO (Houston, Tex.).

[0062] Corrosion inhibitors may also be added to the illustrative wellbore fluids to control corrosion of drilling equipment. Depending upon the type of corrosion encountered, the corrosion inhibitor may be organic or inorganic or some combination thereof. Non-limiting examples of corrosion inhibitors include phosphates, silicates, borates, zinc compounds, organic amines, benzoic acid, and benzoic acid derivatives, phosphate esters, heterocyclic nitrogen and sulfur compounds, organic acids, and the like. Non-limiting examples of commercially available corrosion inhibitors include sodium benzoate and benzotri azole.

[0063] Weighting agents or density materials suitable for use in the illustrative wellbore fluid formulations include, but are not limited to, hematite, magnetite, iron oxides, illmenite, barite, siderite, celestite, dolomite, calcite, manganese oxides, halites and the like. Weighting agents in accordance with the present disclosure may include commercially-available additives such as M-I WATE™ available from M-I L.L.C. (Houston, Tex.). In other embodiments, the weighting agent may be a micronized weighting agent, optionally coated with a dispersant.

[0064] The weighting agent may be coated, for example, with dispersants such as oleic acid and polybasic fatty acids, alkylbenzene sulphonic acids, alkane sulphonic acids, linear alphaolefin sulphonic acids, phospholipids such as lecithin, including salts thereof and including mixtures thereof. Synthetic polymers may also be used including polyacrylate esters such as polymers of stearyl methacrylate and / or butyl acrylate. The corresponding acids, methacrylic acid and / or acrylic acid, may be used.

[0065] The quantity of the coated or uncoated weighting agent added, if any, may depend upon the desired density of the final composition. Weighting agents may be added to result in a density of up to about 22 pounds per gallon (ppg). The weighting agent may be added to achieve a density of up to 20 ppg or up to 19.5 ppg.

[0066] The subject matter disclosed herein may be better understood with reference to the following examples, which are set forth merely to further illustrate the subject matter disclosed herein. The illustrative examples should not be construed as limiting the subject matter in any manner.

[0067] The stability of invert emulsion wellbore compositions formulated with various types of acylated polyolefin-based emulsifiers was assessed under simulated downhole conditions in the following examples. Acylated polyolefin emulsifiers as shown in Table 1 were prepared from polyisobutylene (PIB) acylated with maleic anhydride to form succinated polyisobutylene (PIBsa). The resulting PIBsa is then reacted with alcohols and / or amines to form esters, amides, imides, and combinations thereof. Incomplete conversion of the succinate resulted in formation of ester / acids which then react with pendant amines to form ester / acid salts. The resulting emulsifiers are characterized by total base number (TBN, total acid number (TAN), and nitrogen content (wt% N).Table 11. Acylation methods include chlorination (Cl) followed by Diels Alder and thermal ene (TE) of high vinylidene polyisobutylene2. Polyamine amine bottoms, also called heavy polyamines, comprise polyethylene polyamines with an average composition of hexaethylene heptamine3. Mixture of tall oil fatty acid (TOFA) and amides of TOFA and diethylene triamine

[0068] Testing Group 1 (Primary Emulsifiers 250°F): The samples were formulated as invert emulsions at 75:25 oifwater ratio as shown in Table 2. The mixing procedure for the primary emulsifier in accordance with the present invention involves the following steps: No. 2 diesel fuel, organo clay, primary emulsifier, and lime were combined in a sample cup. The resulting mixture was then mixed on medium speed for 5 minutes using a Hamilton Beach 3- speed mixer. Next, an aqueous solution containing 30% CaCh was added, and the resultingmixture was further mixed on medium speed for 10 minutes. Finally, barite was added, and the final mixture was mixed on high speed for 30 minutes. This mixing procedure ensures thorough blending of the components, resulting in a well-mixed primary emulsifier for further applications.Table 2

[0069] The test muds were evaluated for plastic Viscosity (PV), Yield Point (YP), Ten Second- and Ten-Minute gel strengths, Emulsion Stability (ES) and High Temperature / High Pressure Fluid Loss both before and after hot rolling, as shown in Table 3. The plastic viscosity (PV) of the drilling fluid is calculated by subtracting the 300-rpm shear stress (R300) from the 600-rpm shear stress (R600). The yield point of the drilling fluid (YP) is calculated by subtracting the PV from the R300 reading. The gel strength is the shear stress measured at low shear rate after a mud has set quiescently for a period of time. Emulsion stability is determined by measuring the voltage necessary to break the invert emulsion at standard temperature and pressure. The rheology and electrical stability (ES) of the sample were measured at 150°F, and the data was recorded before hot rolling (BHR); next, the samples were subjected to hot rolling for 16 hours in aging cells at 250°F under a constant pressure of 100 psi; after hot rolling (AHR), the samples were cooled, transferred to a sample cup, and remixed for 15 minutes; the rheology and ES were measured again at 150°F. The fluid loss of the samples was evaluated under high- temperature, high-pressure (HTHP) conditions at 250°F. These testing procedures providevaluable insights into the performance and characteristics of the invention, aiding in the assessment of its effectiveness and suitability for wellbore applications.Table 3

[0070] A second group of primary emulsifiers was evaluated at 350°F. The preparation and testing of the muds was similar to the procedure above with the following changes or additions: organophilic Clay will be changed from Bentone 150 to Bentone 38 for thermal stability; the aqueous brine was calcium bromide (54%). Test muds for higher temperature testing are summarized below in Table 4.Table 4

[0071] As above, the test muds were evaluated for plastic Viscosity (PV), Yield Point (YP), Ten Second- and Ten-Minute gel strengths, Emulsion Stability (ES) and High Temperature / High Pressure Fluid Loss both before and after hot rolling, as shown in Table 5.

[0072] In a filter cake drilling mud lab test, the drilling mud sample is prepared and then placed in a testing cell or a filter press, along with a porous medium like a filter paper or a ceramic disc that mimics the wellbore formation. A controlled pressure is applied to the drilling mud sample, simulating the pressure during drilling. This pressure forces the mud to flow through the porous medium, forming a filter cake on its surface. The filtrate, the liquid that passes through the filter cake, is collected and measured to evaluate the drilling mud's filtration properties and fluid loss control. Once the test is complete, the filter cake is carefully removed and analyzed to determine its thickness, permeability, and other characteristics. The filter cake properties under HTHP conditions are determined using a specialized HTHP filter press. The filter cake thickness is measured using a slide ruler, converted into millimeters from 32nds. For these example HPHT filter press was used at 500 psi on the top of the filter and with a 100 psi pressure on the bottom at 300°F for 30 minutes.Table 5

[0073] Testing Group 3 (Secondary Emulsifiers 250°F with Calcium Bromide Brine): The samples were formulated as invert emulsions at 75:25 oil:water ratio as shown in Table 6. This mixing procedure ensures thorough blending of the components, resulting in a well-mixed primary emulsifier for further applications. The mixing procedure for the secondary emulsifier is as follows: In a sample cup, combine 280 m of diesel, 6g of organo clay, and 10 m of the secondary emulsifier (A, B, C or D). Mix the contents on medium speed for 5 minutes using a Hamilton Beach 3-speed mixer. Next, add 70 mb of 10.8 ppg CaC12 or 14.2 ppg CaBr2 and continue mixing on medium speed for 10 minutes. Finally, add 200g of barite and mix on high speed for 30 minutes.Table 6

[0074] The testing procedures for these samples involves the following steps: first, the rheology and electrical stability (ES) of the sample are measured at 150°F, and the data is recorded (denoted as BHR); next, the samples are subjected to hot rolling for 16 hours in aging cells at 250°F under a constant pressure of 100 psi; after hot rolling, the samples are cooled, transferred to a sample cup, and remixed for 15 minutes; the rheology and ES are measured again at 150°F, and the data is recorded (denoted AHR), with an ES value exceeding 600 considered desirable after hot rolling; finally, the fluid loss of the samples is evaluated under high-temperature, high-pressure (HTHP) conditions at 250°F. Sample compositions and results based on these procedures are shown in the following tables. These testing procedures provide valuable insights into the performance and characteristics of the invention, aiding in the assessment of its effectiveness and suitability for wellbore applicationsTable 7Table 8Table 9

[0075] Additional samples were prepared and tested as follows, with compositions and resting results shown in the following tables: The evaluation of the samples was conducted utilizing the following testing procedures specifically designed for Oil-Based Drilling Fluids.The mixing procedure involved combining 280 mL of diesel, 6g of organophilic clay, 8g of lime, 10 mL of primary emulsifier, 4.5 mL of secondary emulsifier, 70 mL of 10.8 ppg CaCh or 14.2 ppg CaBn, and 150 g of barite in a sample cup using a Hamilton Beach 3-speed mixer. The components were mixed at different speeds, starting with medium speed for 5 minutes for the initial combination of the first four components. Subsequently, the secondary emulsifier was added and mixed for an additional 5 minutes on medium speed. The mixture was further mixed for 10 minutes on medium speed after adding the CaCh or CaBn solution. Finally, the barite was added, and the mixture was mixed on high speed for 30 minutes. The testing procedure involved several steps. Firstly, the rheology and electrical stability (ES) of the sample were checked at 150°F, and the data obtained from these measurements were recorded.Subsequently, the sample was subjected to hot rolling for 16 hours in aging cells at a temperature of 35O°F, with the cells pressurized to 250 psi. After the hot rolling process, the samples were allowed to cool, poured into a sample cup, and remixed for 15 minutes. Rheology and ES measurements were then taken again at 150°F, with an ES value exceeding 600considered desirable after hot rolling. Additionally, the fluid loss and filter cake were evaluated under high-temperature, high-pressure (HTHP) conditions. These testing procedures provide valuable information on the rheological properties, electrical stability, fluid loss, and filter cake formation of the Oil-Based Drilling Fluid samples. Table 10Table 11Table 12Table 13Table 14Table 15Table 16Table 17Table 18Table 19

[0076] The above experimental results illustrate that the utilization of acylated polyolefin emulsifiers, such as PIBSA-based emulsifiers, in the tested fluid led to consistent rheological properties and maintained good emulsion stability throughout the testing process, both before and after hot rolling. These findings demonstrate the effectiveness of PIBSA-based chemistry, specifically the use of a polyolefin anhydride combined with diethylethanolamine as a primary emulsifier and / or a polyolefin anhydride combined with diethanolamine as a secondary emulsifier. This combination proved to be successful in achieving desired performance characteristics in the emulsion.

[0077] Except in the Examples, or where otherwise explicitly indicated or required by context, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word “about”. As used herein, the term “about” means that a value of a given quantity is within ±20% of the stated value. In other embodiments, the value is within ±15% of the stated value. In other embodiments, the value is within ±10% of the stated value. In other embodiments, the value is within ±5% of the stated value. In other embodiments, thevalue is within ±2.5% of the stated value. In other embodiments, the value is within ±1% of the stated value. In other embodiments, the value is within a range of the explicitly-described value which would be understood by those of ordinary skill, based on the disclosures provided herein, to perform substantially similarly to compositions including the literal amounts described herein.

[0078] It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined, and that any amount within a disclosed range is contemplated to provide a minimum or maximum of a narrower range in alternative embodiments (with the proviso, of course, that the minimum amount of a range must be lower than the maximum amount of the same range). Similarly, the ranges and amounts for each element of the subject matter disclosed herein may be used together with ranges or amounts for any of the other elements.

[0079] While certain representative embodiments and details have been shown for the purpose of illustrating the subject matter disclosed herein, it will be apparent to those skilled in this art that various changes and modifications may be made therein without departing from the scope of the subject matter. In this regard, the scope of the invention is to be limited only by the following claims.

Claims

What is claimed is:

1. A composition comprising an oleaginous continuous phase, a non-oleaginous discontinuous phase, and an acylated polyolefin emulsifier, wherein each molecule of the acylated polyolefin emulsifier consists of an oil-soluble polyolefin portion and, on average across all molecules of the acylated polyolefin emulsifier, at least one acyl group attached to the oil-soluble polyolefin portion, wherein the oil-soluble polyolefin portion has a numberaverage molecular weight of 450 to 3000 Daltons, and wherein at least 25 mol% of all the at least one acyl groups present in the acylated polyolefin emulsifier contain at least one of an ester group, a carboxylic acid group, or a carboxylate salt.

2. The composition of claim 1, wherein the acylated polyolefin emulsifier comprises at least one polymer of branched or linear 1 -olefin monomers having from 4 to 8 carbon atoms.

3. The composition of either claim 1 or claim 2, wherein the acylated polyolefin emulsifier comprises at least one polymer of branched or linear monomers having from 4 to 6 carbon atoms, and wherein at least 90 mol percent of the monomers are 1 -butene and / or isobutylene.

4. The composition of any one of claims 1 to 3, wherein ester groups are present in the acylated polyolefin, and the ester groups comprise at least one hydrocarbyl group having from 2 to 18 carbon atoms.

5. The composition of claim 4, wherein the at least one hydrocarbyl group further comprises at least one additional heteroatom comprising at least one of nitrogen or oxygen.

6. The composition of either claim 4 or claim 5, wherein the ester group comprises a hydrocarbyl group substituted with at least one secondary or tertiary nitrogen group.

7. The composition of any one of claims 1 to 6, wherein the acylated polyolefin emulsifier has a total base number of at least 20 mg KOH / g.

8. The composition of any one of claims 1 to 7, wherein the acylated polyolefin emulsifier has a total acid number of at least 10 mg KOH / g.

9. The composition of any one of claims 1 to 8, wherein the acylated polyolefin emulsifier has a total base number and a total acid number, wherein the total acid number is at least 50% of the value of the total base number.

10. The composition of any one of claims 1 to 9, wherein each molecule of the acylated polyolefin emulsifier consists of an oil-soluble polyolefin portion and, on average across all molecules of the acylated polyolefin emulsifier, at least two acyl groups attached to the oilsoluble polyolefin portion, wherein, on average across all molecules of the acylated polyolefin emulsifier, at least one of the at least two acyl groups present in the acylated polyolefin emulsifier is an ester group, and wherein the ester group is an ester of an alkanolamine and the alkanolamine comprises a tertiary or secondary amine.

11. The composition of claim 10, wherein the alkanolamine comprises at least one of diethanolamine, diethyl ethanolamine, triethanolamine, monomethyl ethanolamine, methyl diethanolamine, or aminoethyl ethanolamine.

12. The composition of any one of claims 1 to 11, wherein the acylated polyolefin emulsifier is present in an amount of from 0.1 to 15 weight percent, based on the total weight of the composition.

13. The composition of any one of claims 1 to 12, wherein the composition further comprises a viscosifier.

14. The composition of claim 13, wherein the viscosifier comprises at least one organophilic clay, wherein the organophilic clay comprises at least one of attapulgite, sepiolite, or bentonite.

15. The composition of either claim 13 or claim 14, wherein the viscosifier is present in the composition in an amount from 0.1 to 10 weight percent, based on the total weight of the composition.

16. The composition of any one of claims 1 to 15, wherein the composition further comprises at least one weighting agent.

17. The composition of claim 16, wherein the weighting agent comprises at least one of hematite, magnetite, iron oxide, ilmenite, barite, siderite, celestite, dolomite, calcite, manganese oxide, or halite.

18. The composition of either claim 16 or claim 17, wherein the weighting agent is present in the composition in an amount such that the density of the composition is up to 22 pounds per gallon.

19. The composition of any one of claims 16 to 18, wherein the weighting agent is present in the composition in an amount of from 5 to 30 pounds per gallon, based on the total volume of the composition.

20. The composition of any one of claims 1 to 19, wherein the composition further comprises lime.

21. The composition of claim 20, wherein the lime is present in the composition in an amount from 0.1 to 2 weight percent, based on the total weight of the composition.

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