阅读说明：本技术 包含层状双氢氧化物作为流变改性剂并且包含氨基酰胺作为乳化剂的油基钻井流体组合物 (Oil-based drilling fluid composition comprising a layered double hydroxide as rheology modifier and an aminoamide as emulsifier ) 是由 木萨拉特·哈利玛·穆罕默德 休·克里斯托弗·格林威尔 安德鲁·怀廷 莫纳·艾尔巴塔尔 马诺哈 于 2018-08-10 设计创作，主要内容包括：本申请公开了钻井流体组合物、用于制备钻井流体的方法和用于利用钻井流体钻地下井的方法。根据一个实施例,一种钻井流体组合物可以包含油相、水相、乳化剂和流变改性剂。所述乳化剂可以包含氨基酰胺,并且所述流变改性剂可以包含层状双氢氧化物,例如肉豆蔻酸Mg/Al层状双氢氧化物。(Disclosed herein are drilling fluid compositions, methods for preparing drilling fluids, and methods for drilling subterranean wells with drilling fluids. According to one embodiment, a drilling fluid composition may include an oil phase, an aqueous phase, an emulsifier, and a rheology modifier. The emulsifier may comprise an aminoamide and the rheology modifier may comprise a layered double hydroxide, for example a Mg/Al layered double hydroxide of myristic acid.)

1. An oil-based drilling fluid composition comprising:

a base oil in an oil phase;

water in the aqueous phase;

a rheology modifier comprising a layered double hydroxide;

comprises a formula of R-CO-NH-R' -NH₂The emulsifier of (1); and

one or more additives selected from the group consisting of wetting agents, fluid loss control additives, and weighting additives.

2. The oil-based drilling fluid composition of claim 1, wherein the oil-based drilling fluid comprises 0.1 wt.% to 2 wt.% myristic acid Mg/Al layered double hydroxide drilling fluid, measured on the total weight of the oil-based drilling fluid.

3. The oil-based drilling fluid composition of any of the preceding claims, wherein the oil-based drilling fluid comprises from 0.1 wt.% to 5 wt.% of a composition having the formula R-CO-NH-R' -NH-R "-NH", based on the total weight of the oil-based drilling fluid₂The amino acid amide of (1).

4. The oil-based drilling fluid composition of any preceding claim, wherein the oil-based drilling fluid comprises one or more of:

the base oil in an amount of 10 wt.% to 20 wt.%, based on the total weight of the oil-based drilling fluid;

one or more wetting agents in an amount of 0.1 wt.% to 2 wt.%, based on the total weight of the oil-based drilling fluid;

one or more fluid loss control additives in an amount of 0.5 wt.% to 2 wt.%, based on the total weight of the oil-based drilling fluid; or

One or more weighting additives in an amount of 50 wt.% to 90 wt.%, based on the total weight of the oil-based drilling fluid.

5. The oil-based drilling fluid composition as claimed in any preceding claim, wherein the layered double hydroxide comprises one or more of:

a myristate salt; or

One or more of aluminum cations or magnesium cations.

6. A method for preparing an oil-based drilling fluid composition, comprising:

mixing a base oil, an aqueous component, an emulsifier, and a rheology modifier to form an oil-based drilling fluid composition, wherein:

the oil-based drilling fluid composition comprises an oil phase and an aqueous phase, the oil phase comprising the base oil and the aqueous phase comprising the water;

the rheology modifier comprises a layered double hydroxide; and is

The emulsifier has the formula R-CO-NH-R' -NH₂The amino acid amide of (1).

7. The method of claim 6, wherein the oil-based drilling fluid comprises Mg/Al layered double hydroxide myristate in an amount of 0.1 wt.% to 2 wt.%, based on the total weight of the oil-based drilling fluid.

8. The method of any of claims 6 or 7, wherein the oil-based drilling fluid comprises a fluid having the formula R-CO-NH-R' -NH-R "-NH₂In an amount of 0.1 wt.% to 5 wt.%, based on the total weight of the oil-based drilling fluid.

9. The method of any of claims 6 to 8, wherein the oil-based drilling fluid comprises one or more of:

the base oil in an amount of 10 wt.% to 20 wt.%, based on the total weight of the oil-based drilling fluid;

one or more wetting agents in an amount of 0.1 wt.% to 2 wt.%, based on the total weight of the oil-based drilling fluid;

one or more fluid loss control additives in an amount of 0.5 wt.% to 2 wt.%, based on the total weight of the oil-based drilling fluid; or

One or more weighting additives in an amount of 50 wt.% to 90 wt.%, based on the total weight of the oil-based drilling fluid.

10. The method of any one of claims 6 to 9, further comprising mixing one or more additives selected from wetting agents, fluid loss control additives, and weighting additives with the base oil, the aqueous component, the emulsifier, and the rheology modifier.

11. A method for drilling a subterranean well, the method comprising:

providing an oil-based drilling fluid composition, wherein the oil-based drilling fluid composition comprises:

a base oil in an oil phase;

water in the aqueous phase;

a rheology modifier comprising a layered double hydroxide;

comprises a compound having the formula R-CO-NH-R' -NH₂Wherein R is a fatty acid alkyl group, R' is an alkyl group, and R "is an alkyl group; and

one or more additives selected from the group consisting of wetting agents, fluid loss control additives, and weighting additives; and

operating a drill bit in a wellbore in the presence of the oil-based drilling fluid composition.

12. The method of claim 11, wherein the wellbore comprises one or more of:

wellbore temperature greater than 300 ° f;

a pressure greater than 10,000 psi; or

The surface temperature is 0 ℃ or less.

13. The method of any of claims 11 or 12, wherein the oil-based drilling fluid comprises a fluid having the formula R-CO-NH-R' -NH-R "-NH₂In an amount of 0.1 wt.% to 5 wt.%, based on the total weight of the oil-based drilling fluid.

14. The method of any of claims 11 to 13, wherein the oil-based drilling fluid comprises one or more of:

the base oil in an amount of 10 wt.% to 20 wt.%, based on the total weight of the oil-based drilling fluid;

comprising one or more wetting agents in an amount of 0.1 wt.% to 2 wt.%, based on the total weight of the oil-based drilling fluid;

one or more fluid loss control additives in an amount of 0.5 wt.% to 2 wt.%, based on the total weight of the oil-based drilling fluid; or

One or more weighting additives in an amount of 50 wt.% to 90 wt.%, based on the total weight of the oil-based drilling fluid.

15. The method of any one of claims 11 to 14, wherein the layered double hydroxide comprises one or more of:

a myristate salt; or

One or more of aluminum cations or magnesium cations.

Technical Field

Embodiments of the present disclosure relate generally to materials and methods utilized in natural resource wells, and more particularly to oil-based drilling fluids used in high pressure and high temperature drilling operations.

Acronyms

Throughout this disclosure, the following units of measure or other abbreviated terms are as follows:

degree is equal to degree;

DEG C is centigrade;

f ═ Fahrenheit;

percent is percentage;

al ═ aluminum;

cP is centipoises;

ex. ═ example;

fig. 1;

g is gram;

h is h;

g ═ storage modulus;

g ═ loss modulus;

HTHP is high temperature, high pressure;

mmol to millimole;

mg ═ mg;

mg is Mg;

m L ═ ml;

MPa ═ MPa;

psi pounds per square inch;

pa · s ═ pascal seconds;

s^-1the reciprocal of seconds; and is

wt.% ═ weight percent.

Background

Drilling operations for drilling new wellbores for hydrocarbon extraction, for example, involve the conventional practice of continuously circulating drilling fluid (alternatively referred to as drilling mud) through the wellbore during the drilling operation. Drilling fluid is pumped into the drill pipe and to the bottom of the borehole, from where it then flows up through the annular space between the borehole wall and the drill pipe and finally back to the surface and out of the borehole, where it is recovered for secondary treatment. During drilling, drilling solids (e.g., a portion of the geological formation being drilled) may be carried by the drilling fluid to the surface from at or near the bottom of the wellbore. After the drilling fluid returns to the surface, it may be mechanically or chemically treated to remove the captured solids and cuttings from the drilling fluid and then recirculated back through the wellbore.

Disclosure of Invention

In some drilling processes, the drilling fluid may experience a relatively wide range of environments based on a variety of factors (e.g., ambient temperature and physical strain applied to the drilling fluid). For example, the strain exerted on the drilling fluid may be different based on whether the drilling fluid is in circulation or alternatively in stagnation (e.g., when drilling is stopped). Additionally, the drilling fluid may experience relatively low temperatures at or near the surface of the wellbore (e.g., approximately the air temperature at the surface), but may experience high pressure, high temperature (HPHT) environmental conditions deeper in the geological formation. As the depth of the wellbore increases, the pressure and temperature at the base of the wellbore may increase. The industry-defined definition of HPHT conditions generally includes a wellbore temperature greater than 300 ° F (149 ℃) and a wellbore pressure greater than 10,000psi (68.9 MPa).

Given the circulating nature of the drilling fluid and its function of capturing solids and cuttings during drilling operations, the drilling fluid should flow freely during circulation at a relatively low viscosity to facilitate economical pumping while having sufficient mass to retain and transport cuttings and other solids and suspend the weighting material to maintain a mud column of uniform density in the wellbore under static and circulating conditions. The drilling fluid should also have a gel strength sufficient to suspend solids and cuttings in the event that circulation of the drilling fluid is stopped, to prevent the solids from accumulating at the bottom of the wellbore. The accumulation of solids at the bottom of the wellbore can lead to blockage of the drill bit and physical blockage of the drilling fluid flow path.

However, developing drilling fluids that can operate in HPHT environments is challenging. High temperatures may adversely affect some drilling fluids, causing decomposition of components that cannot withstand high temperatures. Additionally, at high temperatures, some drilling fluids may begin to solidify or experience an increase in viscosity, which may impede circulation. Additionally, drilling fluids suitable for HPHT environments may not operate properly in non-HPHT environments (e.g., at temperatures experienced at the surface and at low depth portions of the wellbore). At these relatively low temperatures, conventional drilling fluids may have relatively high viscosities both when experiencing relatively little strain (e.g., when drilling and fluid circulation is stopped) and when experiencing relatively large amounts of strain (e.g., when drilling is being conducted and when drilling fluid is being circulated).

Accordingly, there is a continuing need for drilling fluids that are thermally stable under HPHT conditions while providing suitable rheological properties at relatively low temperatures, such as those experienced when surface temperatures are relatively low (e.g., at or below 0 ℃, such as in the north). For example, an ideal drilling fluid (e.g., those currently described) may have a lower viscosity for different applied shear stresses at a temperature of 0 ℃ than some conventional drilling fluids. Thus, the presently described drilling fluids may require less energy to circulate while having acceptable solids retention properties when drilling is stopped. Without being bound by theory, it is believed that the incorporation of specific rheology modifiers, emulsifiers, or both may contribute to the desired rheological properties of the presently disclosed drilling fluids. In particular, the addition of layered double hydroxides as rheology modifiers, amino amides as emulsifiers, or both may promote the rheological properties of the drilling fluid, which facilitates drilling in certain environments (e.g., locations where an HPHT environment is present at the bottom of the wellbore at or near freezing surface temperatures).

In accordance with one or more embodiments, an oil-based drilling fluid composition may include a base oil, water, a rheology modifier, an emulsifier, and one or more additives selected from wetting agents, fluid loss control additives, and weighting additives. The base oil may be in the oil phase and the water may be in the water phase. The rheology modifier may comprise a layered double hydroxide. The emulsifier may comprise a compound having the formula R-CO-NH-R' -NH₂The amino acid amide of (1).

According to another embodiment, an oil-based drilling fluid composition may be prepared by a method comprising mixing a base oil, an aqueous component, an emulsifier, and a rheology modifier to form the oil-based drilling fluid composition. The oil-based drilling fluid composition may include an oil phase including a base oil and an aqueous phase, anAnd the aqueous phase comprises water. The rheology modifier may comprise a layered double hydroxide. The emulsifier may comprise a compound having the formula R-CO-NH-R' -NH₂The amino acid amide of (1).

According to yet another embodiment, a subterranean well can be drilled by a method comprising: an oil-based drilling fluid composition is provided, and a drill bit is operated in a wellbore in the presence of the oil-based drilling fluid composition. The oil-based drilling fluid composition may include a base oil in an oil phase, water in an aqueous phase, a rheology modifier, an emulsifier, and one or more additives selected from wetting agents, fluid loss control additives, and weighting additives. The rheology modifier may comprise a layered double hydroxide. The emulsifier may comprise a compound having the formula R-CO-NH-R' -NH₂The amino acid amide of (1).

Additional features and advantages of the described embodiments will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the described embodiments, including the detailed description which follows and the claims.

Drawings

The following detailed description of illustrative embodiments can be understood when read in conjunction with the following drawings.

Fig. 1 is a graph depicting the viscosity of various tested drilling fluids as a function of shear rate at 0 ℃ and 50 ℃, in accordance with one or more embodiments of the present disclosure.

FIG. 2 is a graph depicting the storage modulus (G ') and loss modulus (G') of various tested drilling fluids as a function of percent strain at 50 ℃ in accordance with one or more embodiments of the present disclosure.

Fig. 3 is a graph depicting the phase angle of various tested drilling fluids as a function of percent strain at 50 ℃, in accordance with one or more embodiments of the present disclosure.

Detailed Description

Embodiments of the present disclosure relate to emulsifiers and rheology modifiers for oil-based drilling fluids, and additionally to oils incorporating the disclosed emulsifiers and rheology modifiersA base drilling fluid composition. Oil-based drilling fluids are a combination of a continuous oil phase, an aqueous phase, and at least one emulsifier. The emulsifier may comprise an aminoamide, for example of the formula R-CO-NH-R '-NH-R' -NH₂The emulsifier of (1). The rheology modifier may comprise a layered double hydroxide, such as a Mg/Al layered double hydroxide of myristic acid. For convenience, throughout this disclosure, have the formula R-CO-NH-R' -NH₂The aminoamide emulsifier of (a) may alternatively also be referred to as "formula 1" emulsifier.

To drill a subterranean well, a drill string containing a drill bit and drill collars to weight the drill bit is inserted into a pre-drilled hole and rotated so that the drill bit cuts into the rock at the bottom of the hole. The drilling operation produces rock fragments. To remove rock debris from the bottom of the wellbore, drilling fluid (e.g., an oil-based drilling fluid composition) is pumped down through the drill string to the drill bit. The drilling fluid cools the drill bit, provides lubrication, and lifts rock fragments (known as cuttings) away from the drill bit. As the drilling fluid is recirculated back to the surface, the drilling fluid carries the cuttings upward. At the surface, cuttings are removed from the drilling fluid by secondary operations, and the drilling fluid may be recirculated back down the drill string to the bottom of the wellbore to collect more cuttings. Those skilled in the art will appreciate that multiple terms familiar to those skilled in the art may be used to describe the same item. For example, a subterranean well can alternatively be referred to as a well or a wellbore, and the use of a single term is also intended to encompass each related term.

The drilling fluid comprises drilling mud, packer fluid, suspension, and completion fluid. Typically, drilling fluids have multiple functions, with different types dedicated to specific functions. In one or more embodiments, the oil-based drilling fluid composition suspends the drill cuttings, and the weighting material transports the drill cuttings along with the oil-based drilling fluid composition to the wellbore surface. Additionally, the oil-based drilling fluid composition may absorb gases in the wellbore, such as carbon dioxide (CO)₂) Hydrogen sulfide (H)₂S) and methane (CH)₄) And conveys them to the wellbore surface for release, sequestration, or burnout. The oil-based drilling fluid composition may additionally provide buoyancy to the drill string to follow the wellboreThe increase in length relieves the tension on the drill string. In one or more embodiments, the oil-based drilling fluid composition also provides cooling and lubricating functions for cooling and lubricating the drill bit and drill string used in the drilling operation. In other embodiments, the oil-based drilling fluid composition also controls subsurface pressures. In particular, the oil-based drilling fluid composition may provide hydrostatic pressure in the wellbore to provide support to the sidewall of the wellbore and prevent the sidewall from collapsing and collapsing on the drill string. Additionally, the oil-based drilling fluid composition may provide hydrostatic pressure in the wellbore to prevent fluids in the downhole formation from flowing into the wellbore during drilling operations.

Under certain extreme downhole conditions (e.g., excessive temperatures or complex formations), some properties of the drilling fluid may change. For example, interaction of the drilling fluid with a formation having swelling or dispersible clays or both, or exposure of the drilling fluid to extreme downhole temperatures may result in thickening or dilution of the drilling fluid, excessive increase or decrease in viscosity, or any combination of these. For example, drilling fluids used in High Pressure and High Temperature (HPHT) operations may experience wellbore temperatures greater than 300 ° f (about 149 ℃) and wellbore pressures greater than 10,000psi (about 68.9MPa), which is an industry-defined definition of HPHT conditions. Under HPHT conditions, conventional drilling fluids may decompose or undergo undesirable changes in rheology. In further embodiments, the presently disclosed drilling fluids may behave as desired even under undesirable downhole conditions (e.g., gas influx, which may dilute or chemically destabilize the drilling fluid, or evaporite formation, which may destabilize the drilling fluid).

Embodiments of oil-based drilling fluid compositions are formulated to provide improved rheology. In particular, the oil-based drilling fluid composition may be formulated to include a viscosity at a low shear rate that is similar or greater than that of a conventional HPHT oil-based drilling fluid, a viscosity at a high shear rate that is less or similar, or both (as compared to a conventional HPHT oil-based drilling fluid). The greater viscosity at low shear rates allows the oil-based drilling fluid composition to effectively retain drill cuttings when drilling operations are stopped. Conversely, less high shearThe viscosity at shear rate results in less power being required to circulate the oil-based drilling fluid composition during the drilling operation. As presently stated, a low shear rate may be described as, for example, less than or equal to 10s^-1And high shear rates may describe, for example, greater than or equal to 100s^-1The shear rate of (c).

In one or more embodiments, the oil phase comprises a base oil. The oil phase of oil-based drilling fluids may comprise synthetic oils or natural petroleum products as base oils. The natural petroleum derived product may comprise an oil, such as diesel or mineral oil. Synthetic oils may include esters or olefins. Furthermore, synthetic oils or natural petroleum products may be composed of hydrocarbons, such as n-paraffins, iso-paraffins, cyclo-paraffins, branched paraffins or mixtures thereof. For example, the base oil may comprise C8 to C26 straight or branched chain saturated alkyl hydrocarbons, such as may be found in Saraline 185V, commercially available from Shell. Additional base oils may include, but are not limited to, DF-1 and EDC99-DW available from Total and Escaid 110 available from Exxon Mobil. Additional suitable base oils may comprise one or more of mineral oil, paraffin, or diesel. In various embodiments, the oil-based drilling fluid composition may comprise 5 wt.% to 45 wt.% (e.g., 5 wt.% to 30 wt.%, 5 wt.% to 20 wt.%, 5 wt.% to 15 wt.%, 5 wt.% to 10 wt.%, 10 wt.% to 45 wt.%, 15 wt.% to 45 wt.%, 20 wt.% to 45 wt.%, 30 wt.% to 45 wt.%, 5 wt.% to 25 wt.%, or 10 wt.% to 20 wt.%) base oil, based on the total weight of the oil-based drilling fluid composition.

The aqueous phase of the oil-based drilling fluid may comprise water and a salt source. In one or more embodiments, the water comprises one or more of: deionized water, tap water, distilled water or fresh water; or natural, brackish and saturated saline; natural, salt dome, hydrocarbon formation produced or synthetic brines; filtered or untreated seawater; mineral water; and other drinking and non-drinking water containing one or more dissolved salts, minerals or organic substances. In some embodiments, the aqueous phase may include, for example, a brine comprised of water and a salt selected from one or more of calcium chloride, calcium bromide, sodium chloride, sodium bromide, and combinations thereof. The oil-based drilling fluid may contain from 2 wt.% to 10 wt.% of an aqueous phase, based on the total weight of the oil-based drilling fluid. In various embodiments, the oil-based drilling fluid composition may have 2 to 12 wt.% (e.g., 4 to 10 wt.%, 2 to 8 wt.%, 2 to 6 wt.%, 2 to 5 wt.%, 3 to 10 wt.%, 3 to 8 wt.%, 3 to 6 wt.%, 4 to 10 wt.%, 4 to 8 wt.%, 4 to 6 wt.%, or 4 to 5 wt.%) aqueous phase, based on the total weight of the oil-based drilling fluid composition. In some embodiments, the oil-based drilling fluid may have an oil-to-water volume ratio of 50:50 to 95:5, 75:20 to 95:5, 85:15 to 95:5, or 90:10 to 95:5, for example. The oil-to-water ratio of an oil-based drilling fluid composition is a volume ratio calculated as: the oil part of water, namely base oil, surfactant, emulsifier, wetting agent and layered double hydroxide, and the water part of water and saline water. As an example and not by way of limitation, wherein the brine may be X% water (by volume), X% of the brine volume is included as water by volume.

The oil-based drilling fluid comprises at least one emulsifier. The emulsifier may assist in forming an emulsion of the aqueous phase of the oil-based drilling fluid composition within the oil phase of the oil-based drilling fluid composition. The inclusion of an emulsifier in the oil-based drilling fluid composition may help prevent separation of the oil and water phases.

In one or more embodiments, the emulsifier comprises an aminoamide. The aminoamide may be a compound comprising an amino functionality (-NH)₂) And any molecule that is amide functional. In some embodiments, the aminoamide can include the structure depicted in chemical structure 1.

The aminoamide of chemical structure 1 may be referred to as "emulsifier of formula 1" or include the formula R-CO-NH-R' -NH-R "-NH₂The molecule of (1).

In one or more embodiments, the amount of the emulsifier of formula 1 in the drilling fluid composition may be from 0.05 weight percent (wt.%) to 5 wt.%, from 0.1 wt.% to 2 wt.%, from 0.1 wt.% to 1.5 wt.%, from 0.1 wt.% to 1 wt.%, from 0.5 wt.% to 2.5 wt.%, based on the total weight of the drilling fluid compositionThe oil-based drilling fluid may comprise additional emulsifiers, further exemplary emulsifiers comprise fatty acids, reverse emulsifiers and oil wetting agents of a synthetic-based drilling fluid system, such as L E super mu L available from haliiburton Energy Services, inc^TMAnd MU L XT L E SUPERMU L, commercially available from M-I SWACO^TMIs a carboxylic acid terminated polyamide.

In one or more embodiments, the total amount of emulsifier in the drilling fluid composition comprising the emulsifier of formula 1 and the additional emulsifier can be 0.05 wt.% to 5 wt.%, 0.1 wt.% to 2.5 wt.%, 0.1 wt.% to 1.5 wt.%, 0.1 wt.% to 1 wt.%, 0.5 wt.% to 2.5 wt.%, 0.5 wt.% to 2 wt.%, 0.5 wt.% to 1.5 wt.%, 0.5 wt.% to 1 wt.%, 0.75 wt.% to 2 wt.%, 0.75 wt.% to 1.5 wt.%, 0.75 wt.% to 1 wt.%, 0.8 wt.% to 1 wt.%, or 0.9 wt.% to 1.1 wt.% (() based on the total weight of the drilling fluid composition.

In one or more embodiments, include the formula R-CO-NH-R' -NH₂The R group in the aminoamide of (1) includes a hydrocarbon group. As described, "hydrocarbyl" refers to a group formed by removing one or more hydrogen atoms from a hydrocarbon (i.e., removing one hydrogen from a group (e.g., R) attached to a backbone structure at one point, removing two hydrogens from a group (e.g., R' and R ") attached to a backbone structure at two points, and the like₁₇H₃₅. In another embodiment, the R group may be linear or notSaturated hydrocarbon groups, including alkene groups containing 1 to 100 carbon atoms (such as, for example, 1 to 50 carbon atoms, 1 to 25 carbon atoms, 10 to 25 carbon atoms, 15 to 20 carbon atoms, or 16 to 18 carbon atoms₇H₁₄CHCHC₈H₁₇。

In one or more embodiments, the R' group, R "group, or both, can include a linear hydrocarbon group, such as an alkyl or alkenyl group. The R' group, R "group, or both can contain 1 to 20 carbon molecules, such as 1 to 10 carbon atoms, 1 to 5 carbon atoms, or 1 to 3 carbon atoms. For example, the R 'group, the R' group, or both can include a dicarbalkyl group (i.e., -CH)₂CH₂-)。

According to one embodiment, the emulsifier of formula 1 may have a formula of-C₁₇H₃₅R group of (A) and-CH₂CH₂The R 'and R' groups of (A-B). This embodiment is depicted as chemical structure 2.

In an embodiment, the oil-based drilling fluid composition comprises a rheology modifier. For example, the rheology modifier may be a viscosifier to impart non-newtonian fluid rheology to the oil-based drilling fluid composition to facilitate the entrainment and transport of cuttings to the wellbore surface. In one or more embodiments, the oil-based drilling fluid may include a layered double hydroxide (e.g., a Mg/Al myristic acid layered double hydroxide) as a rheology modifier. As used in this disclosure, layered double hydroxide refers to a layered double hydroxide having the general layer sequence [ ACBZADB]_nWherein C and D layers represent metal cations, a and B layers represent hydroxide anion layers, Z represents another ionic layer, and n represents the number of repeating units in the structure. According to one or more embodiments, the C and D layers may comprise different metal cations. For example, layer C may comprise magnesium cations, such as divalent magnesium cations, and layer D may comprise aluminum cations, such as trivalent aluminum cations. However, other metal cations are contemplated in the present disclosure, such as any metal that can form a cation. For exampleBut are not limited to, L i, cations of Zn, Co, Ni, Ca, Fe, or Ga may be contained in the layered double hydroxide, the Z layer may contain a myristate salt, which is a salt or ester of myristic acid, myristic acid having the general formula (CH)₃)(CH₂)₁₂COOH, and the myristate ion contained in the layered double hydroxide may have the general formula (CH)₃)(CH₂)₁₂COO^-. According to one or more embodiments, the layered double hydroxide has the formula:

[C_1-xD_x(OH)₂]^Y+(OOC(CH₂)₁₂CH₃)^Y-

wherein x is from 0.1 to 0.33 and Y represents the ionic charge of the metal cation and the myristate anion.

According to one or more embodiments, the layered double hydroxide may be manufactured by a process comprising mixing a cationic salt and a myristate salt in water, followed by hydrothermal treatment of the mixture at an elevated temperature (e.g., at least 100 ℃, at least 125 ℃, or 150 ℃ or higher (e.g., 100 ℃ to 200 ℃)) for 4 hours to one week (e.g., 6 hours to 48 hours). After the reaction by the hydrothermal treatment, the double layered hydroxide may be separated from other substances by dispersing the reaction product in a solvent (e.g., acetone) and optionally stirring at room temperature for at least 1 minute (e.g., 15 minutes to 45 minutes). After the acetone treatment, the double layered hydroxide can be recovered by heating to high temperature in an oven and then washing with hot water.

In one or more embodiments, the bi-layered hydroxide may include magnesium and aluminum, and the molar ratio of magnesium to aluminum may be from 0.5 to 10, such as from 1 to 5. In further embodiments, the molar ratio of myristate to total metal cations may be 1 to 3, for example 1 to 2 or 1.5. According to one or more embodiments, the use of Mg (NO) can be used₃)₂·6H₂O、Al(NO₃)₃·9H₂O, urea and sodium myristate, to prepare the layered double hydroxide.

According to an embodiment, the layered doubleIn some embodiments, the oil-based drilling fluid composition may optionally comprise an organophilic hectorite clay, such as VERSAGE L HT commercially available from MI-SWACO, Houston, Texas, or an organophilic clay, such as VERSAGE L HT commercially available from Elements Specialties Inc, Haysian (Highstown), N.J., a polymer blend of a polymer with a polymer having a cross-linking index of greater than one and greater than one42。

An exemplary oil-based drilling fluid composition may comprise 0.1 wt.% to 0.8 wt.% rheology modifier (based on the total weight of the oil-based drilling fluid composition). In some embodiments, the oil-based drilling fluid composition may comprise 0.1 wt.% to 0.7 wt.% layered double hydroxide, such as Mg/Al myristic acid layered double hydroxide. For example, at least 0.1 wt.%, at least 0.2 wt.%, at least 0.3 wt.%, at least 0.4 wt.%, at least 0.5 wt.%, at least 0.6 wt.%, at least 0.7 wt.%, or at least 0.8 wt.% of the oil-based drilling fluid may be a rheology modifier.

The oil-based drilling fluid composition further comprises one or more additives. Exemplary additives include, but are not limited to, wetting agents, fluid loss control additives, and weighting additives. The oil-based drilling fluid composition may also optionally include alkalinity modifiers, electrolytes, glycols, glycerin, dispersion aids, corrosion inhibitors, defoamers, and other additives or combinations of additives.

In embodiments, the oil-based drilling fluid composition may include weighting additives to increase the weight, density, or both of the oil-based drilling fluid. Weighting additives may be used to control formation pressure and help resist the effects of shale collapse or collapse that may be encountered in a stress zone. Any substance that is denser than water and does not adversely affect other properties of the drilling fluid may be used as the weighting material. In some embodiments, the weighting material may be a composite material havingA particulate solid of a Specific Gravity (SG) sufficient to increase the density of the drilling fluid composition without the addition of excess weighting material by an amount such that the drilling fluid composition cannot be circulated through the wellbore. The weight material may have a Specific Gravity (SG) of 2 grams per cubic centimeter (g/cm)³) To 6g/cm³. An example of a weight or density modifier includes barite (BaSO)₄) Galena (PbS), hematite (Fe)₂O₃) Magnetite (Fe)₃O₄) Artificial iron oxide, ilmenite (FeO. TiO)₂) Siderite (FeCO)₃) Celestite (SrSO)₄) Dolomite (CaCO)₃·MgCO₃) And calcite (CaCO)₃)。

The oil-based drilling fluid composition may include an amount of a weighting additive sufficient to increase the density of the drilling fluid composition to allow the drilling fluid composition to support the wellbore and prevent fluid in the downhole formation from flowing into the wellbore. In an embodiment, the oil-based drilling fluid composition may comprise 1 wt.% to 80 wt.% of a weighting additive, based on the total weight of the oil-based drilling fluid composition. In some embodiments, the oil-based drilling fluid composition may comprise 1 wt.% to 90 wt.%, 20 wt.% to 80 wt.%, 20 wt.% to 75 wt.%, 50 wt.% to 80 wt.%, 50 wt.% to 75 wt.%, 60 wt.% to 80 wt.%, 60 wt.% to 75 wt.%, 65 wt.% to 80 wt.%, or 70 wt.% to 80 wt.% weighting additive, based on the total weight of the oil-based drilling fluid composition. In some embodiments, the oil-based drilling fluid composition may comprise 50 wt.% to 90 wt.% of a weighting additive, based on the total weight of the oil-based drilling fluid composition.

The oil-based drilling fluid composition may optionally comprise at least one alkalinity modifier. In embodiments, the oil-based drilling fluid composition may optionally comprise at least one alkaline compound to adjust the pH of the oil-based drilling fluid composition. Examples of alkaline compounds may include, but are not limited to, lime (calcium hydroxide or calcium oxide), soda ash (sodium carbonate), sodium hydroxide, potassium hydroxide, other strong bases, or combinations of these alkaline compounds. It should be noted that pK_aConjugate bases of acids greater than about 13 are considered strong bases. The alkaline compound can be used for drillingGases (e.g., CO) encountered by fluid compositions during drilling operations₂Or H₂S) reacting to prevent gas hydrolysis of components of the water-based drilling fluid composition. Some example water-based drilling fluid compositions may optionally include 0.1 wt.% to 3 wt.%, 0.4 wt.% to 2 wt.%, or 0.6 wt.% to 0.8 wt.% lime.

In one or more embodiments, surfactants (e.g., wetting agents) may be added to enhance the stability of suspensions or emulsions in oil-based drilling fluid compositions. Suitable wetting agents may include fatty acids, organic phosphate esters, modified imidazolines, amidoamines, alkyl aromatic sulfates and sulfonates. For example, commercially available from M-I SWACO, Houston, TexIs an oil-based wetting agent and secondary emulsifier that can be used to wet fines and drilling solids to prevent solids from being wetted by water. In addition to this, the present invention is,can improve thermal stability, rheological stability, filtration control, emulsion stability of wellbore fluids, commercially available from M-I LL C, Houston, TexIs another wetting agent that is particularly effective in hematite systems that are difficult to wet. Exemplary oil-based drilling fluid compositions may optionally comprise 0.1 wt.% to 2 wt.% wetting agent, based on the total weight of the oil-based drilling fluid composition. In some embodiments, the oil-based drilling fluid composition may optionally comprise 0.25 wt.% to 0.75 wt.% of each(based on the total weight of the oil-based drilling fluid composition). Other suitable wetting agents may optionally be included in the oil-based drilling fluid composition without departing from the scope of the present subject matter.

In one or more embodiments, the fluid may be lostExamples of fluid loss control additives include organophilic (e.g., amine-treated) lignite, bentonite, man-made polymers, and diluents or antiflocculants when used, they may constitute from 0.5 wt.% to 3 wt.% of the oil-based drilling fluid composition, in various embodiments, the fluid loss control additives may constitute from 0.5 wt.% to 1.5 wt.%, from 0.5 wt.% to 1.25 wt.%, from 0.75 wt.% to 2 wt.%, from 0.75 wt.% to 1.5 wt.%, from 1.75 wt.% to 1.25 wt.%, from 1 wt.% to 1.25 wt.%, or from 1 wt.% to 1.25 wt.% of the oil-based drilling fluid composition, based on the total weight of the drilling fluid, in various embodiments, the fluid loss control additives include versat L ro, an exemplary fluid loss control additive comprising ro, from 0.75 wt.% to 1.25 wt.%, from 1 wt.% to 1.25 wt.%, or from 1 wt.% to 1.25wt^TM、VERSALIG^TM、ECOTROL^TMRD、ONETROL^TMHT, EMI 789 and NOVATECH^TMF (all commercially available from MI SWACO, Houston, Tex.) and(commercially available from Halliburton Energy Services, inc.) in some embodiments, the oil-based drilling fluid composition may optionally include about 10:1 weight ratios of ONETRO L, respectively^TMHT and ECOTRO L^TMRD。

An optional suspension may be added to the oil-based drilling fluid composition to adjust the viscosity of the oil-based drilling fluid composition to have a yield point at a low shear rate sufficient to suspend all of the drilling fluid components, whereby settling of the components of the oil-based drilling fluid composition may be avoided. An example of a suspension comprises a fatty acid and a fibrous material. When suspensions are used, they may constitute from about 0.0 wt.% to about 1.0 wt.% or 0.01 to 0.5 wt.% of the oil-based drilling fluid composition, based on the total weight of the drilling fluid.

In accordance with one or more embodiments, maintaining a suspension of solids and cuttings in the oil-based drilling fluid composition during low-speed drilling or between drilling operations, a viscosity above a threshold at a lower shear rate is advantageous. At one or moreIn the examples, the oil-based drilling fluid has a shear rate of 10.22s measured at 50 ℃ or 0 ℃ at atmospheric pressure^-1The viscosity at time is at least 385cP, at least 1000cP or even at least 1850 cP.

In accordance with one or more embodiments, it is advantageous to allow the oil-based drilling fluid composition to circulate without the need for excessive energy during viscosity below a threshold at higher shear rates. In one or more embodiments, the oil-based drilling fluid has a shear rate of 170s measured at 50 ℃ or 0 ℃ at atmospheric pressure^-1The viscosity of less than or equal to 222cP, less than or equal to 175cP, or even less than or equal to 128 cP.

Having described the oil-based drilling fluid composition in accordance with various embodiments, an illustrative method for preparing the oil-based drilling fluid composition will now be described. A method for preparing an oil-based drilling fluid may include mixing a base oil, at least one emulsifier, and at least one wetting agent to form a first mixture, wherein the at least one emulsifier comprises an amino amide comprising the formula R-CO-NH-R' -NH-R "-NH ″₂. The ingredients of the first mixture may be added to provide the amounts previously described with respect to the embodiments of the oil-based drilling fluid composition. The method for preparing an oil-based drilling fluid composition may optionally comprise mixing at least one rheology modifier (e.g., a Mg/Al layered double hydroxide myristate) and an alkalinity regulator into the first mixture to form a second mixture. Likewise, the ingredients of the second mixture may be added to provide the amounts previously described with respect to the embodiments of the oil-based drilling fluid composition. The method for preparing an oil-based drilling fluid composition may optionally comprise mixing at least one fluid loss control additive into the second mixture to form a third mixture. Likewise, the ingredients of the third mixture may be added to provide the amounts previously described with respect to the embodiments of the oil-based drilling fluid composition. The method for preparing an oil-based drilling fluid composition may further comprise mixing a brine solution into the first mixture or the third mixture to form a fourth mixture. The ingredients of the fourth mixture may be added to provide the amounts previously described with respect to the embodiments of the oil-based drilling fluid composition. For makingThe method of preparing an oil-based drilling fluid composition may further comprise mixing a weighting additive into the fourth mixture to form the oil-based drilling fluid composition. The ingredients of the oil-based drilling fluid composition may be added to provide the amounts previously described with respect to the embodiments of the oil-based drilling fluid composition.

The previously described oil-based drilling fluid compositions may be well suited for drilling operations in subterranean formations, particularly drilling operations conducted under HPHT conditions where the wellbore pressure is greater than 10,000psi and the wellbore temperature is greater than 300 ° f (149 ℃). Accordingly, embodiments of a method for drilling a well in a subterranean well under high pressure and high temperature conditions may comprise providing an oil-based drilling fluid composition according to any of the embodiments described herein. A method for drilling a well in a subterranean well under high pressure and temperature conditions includes operating a drill bit in a wellbore in the presence of an oil-based drilling fluid composition.

Examples of the invention

The following examples illustrate one or more additional features of the present disclosure. It should be understood that these examples are not intended to limit the scope of the present disclosure or appended claims in any way.

The emulsifier of chemical structure 2 was synthesized by adding stearic acid (0.28g, 1mmol), boric acid (3.09mg, 0.05mmol) and toluene (3ml) to a flask equipped with a Dean-Stark trap, to which a reflux condenser was fitted. Diethylenetriamine (0.11g, 1.1mmol) was added to the reaction mixture with stirring. The reaction mixture was heated to reflux overnight (at least 14 hours). The mixture was allowed to cool to room temperature and then poured into hexane with stirring, resulting in immediate precipitation of a solid, which was filtered off and washed with hexane to give a solution comprising the formula R-CO-NH-R' -NH-R "-NH according to an example of the present disclosure₂The desired aminoamide emulsifier.

Mg/Al layered double hydroxide myristic acid was produced. Mg (NO)₃)₂·6H₂O、Al(NO₃)₃·9H₂O, urea and sodium myristate were purchased from Sigma Aldrich as starting materials and used without further purification. During the whole synthesis process, the catalyst is prepared byPurifying purified water treated by the water purification system and decarbonating the water by heating at 75 ℃ to avoid any CO₂And (4) pollution. To form the layered double hydroxide, 11.596g of Mg (NO)₃)₂·6H₂O、8.35g Al(NO₃)₃·9H₂O and 12.16g of urea were placed in a Teflon lined 1000m L autoclave, the Mg/Al molar ratio was 2, and the urea to metal molar ratio was 3. to this mixture 25.34g of sodium myristate and 500m L hot decarbonated brine were added to form a mixture with a myristate/metal molar ratio of 1.5. the resulting reaction mixture was hydrothermally treated at 150 ℃ for 24 hours.

To compare the physical and rheological properties of a drilling fluid containing the emulsifier of chemical structure 2 and the Mg/Al layered double hydroxide rheology modifier of myristic acid with those of a drilling fluid containing industry standard emulsifiers and rheology modifiers, two drilling fluids were prepared. Both drilling fluids are based on M-I SWACO RHADIANT^TMA system comprising a blend of a proprietary emulsifier, wetting agent, and fluid loss control additive customized for an oil-based fluid formulation. In particular, use is made ofComparative drilling fluids (comparative example a) were prepared as emulsifiers and using VERSAGE L HT and Bentone 42 as rheology modifiers by replacing the emulsifier of chemical structure 2And substituting myristic acid Mg/Al layered double hydroxideInstead of VERSAGE L HT and Bentone 42 to prepare a second drilling fluid (example 1) it should be noted that the total amount of emulsifiers in example 1 is less than the total amount of emulsifiers in comparative example A and the total amount of rheology modifiers in example 1 is less than the total amount of rheology modifiers in comparative example A. thus, example 1 will have better environmental properties than comparative example A.

Comparative example a and example 1 drilling fluids were formulated using the following ingredients: saraline 185V, a synthetic oil drilling base fluid, available from Shell;an amidoamine surfactant is commercially available from M-I SWACO, &lTtT transfer = LL "&gTt LL &lTt/T &gTt C (Houston, Tex., USA);a wetting agent is available from M-I SWACO, &lTtTtransfer = LL "&" gTt LL &/T & "gTt C (Houston, Tex., USA); MU L XT, an emulsifier for non-aqueous fluid systems, available from M-I SWACO, &lTtTtransfer = LL" &gTtLL &/T &/gTt C (Houston, Tex., USA); VERSAGE L HT, a hectorite tackifier for aiding in filtration control, available from M-I SWACO, &lTtTtransfer = LL & "gTtTtT &/T &" gTt C (Houston, Tex., USA); (U.S.) (Bentsingtone 42, New Yongte) incorporated L)^TMHT, an amine treated tannin filtration control additive designed for oil and synthetic based drilling fluid systems, available from M-I SWACO, &lTtTtransformation = LL "&gTtLL &lTt/T &gTtC (Houston, Tex., USA), ECOTRO L RD, a filtration control additive designed for oil and synthetic based drilling fluid systems, available from M-I SWACO, &lTtransformation = TtTtLL &/T &gTtC (Houston, Tex., USA), and barite (BaSO)₄) Weighting additives, commercially available from M-I SWACO, &lTtTtransformation = LL "&gTtLL &lTt/T &gTtC (Houston, Tex., USA.) additionally, lime was used, which had a specific gravity of 2.24 at 20 ℃ and a bulk density of 400kg/M³；CaCl₂Saline is available from Schlumberger; and contains fresh water.

30.88g and 25.27g of the drilling fluids of comparative example A and example 1, respectively, were prepared using a magnetic stir bar. Are provided in Table 1Formulations of the drilling fluids of comparative example a and example 1 are shown. To prepare the drilling fluid, the base oil, emulsifier and wetting agent are first mixed together for 10 minutes during phase 1. Specifically, willWas added to comparative example a as an emulsifier and the emulsifier of formula 1 was added to example 1 as an emulsifier. Then, the rheology modifier was added during stage 2 and mixed for an additional 20 minutes, with the Mg/Al layered double hydroxide of myristic acid used in example 1 (but not used in comparative example a). Next, in stage 3, the fluid loss control additive was added and mixed for 20 minutes, followed by the addition of brine and fresh water in stage 4 and barite in stage 5, mixed for 30 and 40 minutes, respectively. The amount of base oil and wt.% of barite used was slightly different for comparative example a and example 1, such that the specific gravity of comparative example a and example 1 was 2.20 and the oil/water ratio was 90.0. It should be noted that in the examples, the oil to water ratio does not include the oil portion of the layered double hydroxide.

Table 1: formulation and mixing procedure for HPHT oil-based drilling fluids

After 17 hours of mixing, the drilling fluids of comparative example a and example 1 were left to stand and then examined for sag and fluid separation prior to rheological measurements. Fluid separation and sagging were visually inspected. Specifically, an inspection of the visual separation of solids and liquids was performed. Sag can also be checked by inserting a micro-spatula into the mud to check if the mud is the same texture from top to bottom (subjectively hard or soft) and if there is separation and settling of solids so that the solids are no longer evenly distributed throughout the drilling fluid. If there is a sag phenomenon (as evidenced by separation and settling of solids), the mud will appear softer at the top of the vessel where the drilling fluid is standing and harder at the bottom. As described, sag refers to the situation where solids settle with increased density, such as where heavier materials (e.g., barite) move to the bottom, and vigorous mixing may be required to disperse the solids back into solution. Fluid separation means that the fluid is separated at the top, but the contents of the components remain dispersed, while no heavy solids are separated from the rest of the components and settle at the bottom.

The viscosity of the drilling fluid was measured using a stress and strain controlled Rheometer (TA Instrument, necauser, discover hybrid Rheometer in tera). The geometry used in the rheometer was 25mm rough stainless steel parallel plates. This geometry was chosen because of the presence of particulate barite in the sample. The gap between the stainless steel plates was set to 300 μm. Shear rate was carried out at atmospheric pressure at 0 ℃ and 50 ℃ (0.004 to 2000 s)^-1) Measurement of the changed viscosity. When no force is applied, the drilling fluids of comparative example a and example 1 gelled and were strong enough to hold the drilling solids and weighting material (e.g., barite). In addition, shear rate experiments provide useful fluid viscosity information and whether the fluid has zero shear or shear dilution. Shear rate experiments also indicate the shear rate at which the drilling fluid deforms.

Figure 1 depicts the viscosity of the test samples as a function of shear rate at 0 ℃ and 50 ℃. In addition, selected results from rheological measurements are shown in FIG. 1

Table 2: HPHT oil-based drilling fluid rheology

Referring to fig. 1 and table 2, both comparative example a and example 1 exhibited shear thinning behavior regardless of their formulations and test temperatures. However, at 50 ℃, example 1 had a greater relatively lower shear rate (e.g., 10.22 s) than comparative example a at the same temperature and shear rate^-1) And thus the example 1 drilling fluid was able to better hold solids while being fixed (compared to the comparative example a drilling fluid at 50 ℃). However, at 50 deg.CExample 1, below, has a greater shear rate of 170s^-1This means that additional energy will be required during the fluid circulation. The relative viscosities of example 1 and comparative example a at 50 ℃ show that example 1 will hold the solids better while stationary due to the greater viscosity at low shear rate when compared to comparative example a, but will require more power during circulation of the drilling fluid due to the greater viscosity at high shear rate. Thus, the example 1 drilling fluid may be superior to the comparative example a drilling fluid if increased viscosity is required to maintain solids during stagnation.

As shown in FIG. 1 and Table 2, the drilling fluid of example 1 was at 0 deg.C for 10.22s^-1Lower viscosity than comparative example A drilling fluid phase and 170s at 0 deg.C^-1The viscosity of the drilling fluid is also less than that of comparative example a. Thus, although the gel strength of example 1 during drilling stagnation may be slightly lower than comparative example a, less energy would be required to circulate the example 1 drilling fluid at 0 ℃. Thus, the example 1 drilling fluid may be superior to the comparative example a drilling fluid at 0 ℃ as long as the viscosity of the example 1 drilling fluid is acceptable for maintaining solids during stagnation.

Additionally, the example 1 drilling fluids exhibited the characteristic of a brittle gel, such that they gelled once the stress was removed. This is related to the fact that once drilling is stopped, the drilling fluid will gel, so that the drilling fluid will effectively support the cuttings.

Table 3: oil-based drilling fluids: strain at deformation and fluid separation%

Neither example 1 nor comparative example a showed sagging and showed only trace or no separation after 17 hours of standing after preparation. As shown in table 3 and fig. 2-3, both example 1 and comparative example a deformed at about the same strain at 50 ℃, so both would require similar power to initiate drilling.

The storage modulus (G ') and loss modulus (G') are plotted as a function of% strain at 50 deg.C in FIG. 2. In addition, the phase angle as a function of% strain at 50 ℃ is depicted in fig. 3. The storage modulus (G') of example 1 is greater than the loss modulus (G "), indicating that it has solid-like properties similar to comparative example a. Both G' and G "values for comparative example a are greater than comparative example a, but it deforms at 50 ℃ with a slightly greater strain and therefore does not require excessive power when starting the drilling, but will require more power during the cycle because it will remain semi-liquid for a longer period of time due to the greater strain/shear it will undergo when deforming to the liquid state, thus requiring more power. Similar to the comparative example a drilling fluid, the phase angle of the example 1 drilling fluid exhibited solid-like behavior at small strains, while the liquid behavior at larger strains. A large strain is required before the drilling fluid of example 1 begins to behave like a liquid at 50 ℃.

Additionally, it is contemplated that drilling fluids with reduced amounts of brine may have reduced viscosity because an increase in viscosity is observed during the preparation of the drilling fluid upon addition of brine. It is contemplated that reducing the brine or using another brine (e.g., NaCl) may reduce the viscosity.

It should be noted that the total amount of emulsifier used in example 1 was less than comparative example a. It is therefore contemplated that the example 1 drilling fluid may be more environmentally friendly than the comparative example a drilling fluid.

It should be understood that any two quantitative values assigned to a property may constitute a range for the property, and all combinations of ranges formed from all of the quantitative values for a given property are contemplated in this disclosure. It is understood that in some embodiments, the compositional range of a chemical component in a composition or formulation should be understood to contain a mixture of isomers of the component. It is to be understood that the examples provide compositional ranges for the various compositions, and that the total amount of isomers of a particular chemical composition can comprise a range.

It is noted that one or more of the following claims use the term "wherein" as a transitional phrase. For the purpose of defining the present technology, it is noted that this term is introduced in the claims as an open transition phrase that is used to introduce a recitation of a series of characteristics of a structure, and is to be interpreted in a similar manner as the more commonly used open-ended preface term "comprising".

It should be understood that any two quantitative values assigned to a property may constitute a range for the property, and all combinations of ranges formed from all of the quantitative values for a given property are contemplated herein.

It will be apparent to those skilled in the art that various modifications can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the present specification cover the modifications and variations of the various embodiments described, provided such modifications and variations come within the scope of the appended claims and their equivalents.

The presently described subject matter may incorporate one or more aspects that should not be viewed as limiting the teachings of this disclosure. The first aspect may comprise an oil-based drilling fluid composition comprising: a base oil in an oil phase; water in the aqueous phase; a rheology modifier comprising a layered double hydroxide; comprises a formula of R-CO-NH-R' -NH₂The emulsifier of (1); and one or more additives selected from the group consisting of wetting agents, fluid loss control additives, and weighting additives.

A second aspect may comprise a method for preparing an oil-based drilling fluid composition comprising: mixing a base oil, an aqueous component, an emulsifier, and a rheology modifier to form an oil-based drilling fluid composition, wherein: the oil-based drilling fluid composition comprises an oil phase and an aqueous phase, the oil phase comprising the base oil and the aqueous phase comprising the water; the rheology modifier comprises a layered double hydroxide; and the emulsifier comprises a compound having the formula R-CO-NH-R' -NH₂The amino acid amide of (1).

A third aspect may include a method for drilling a subterranean well, the method comprising: providing an oil-based drilling fluid composition, wherein the oil-based drilling fluid composition comprises: a base oil in an oil phase; water in the aqueous phase; a rheology modifier comprising a layered double hydroxide; comprises a compound having the formula R-CO-NH-R' -NH₂Emulsification of the amino acid amides ofAn agent, wherein R is a fatty acid alkyl group, R' is an alkyl group, and R "is an alkyl group; and one or more additives selected from the group consisting of wetting agents, fluid loss control additives, and weighting additives; and operating the drill bit in the wellbore in the presence of the oil-based drilling fluid composition.

Another aspect includes any of the preceding aspects, wherein the oil-based drilling fluid comprises Mg/Al layered double hydroxide myristate in an amount of 0.1 wt.% to 2 wt.%, based on the total weight of the oil-based drilling fluid.

Another aspect includes any of the preceding aspects, wherein the oil-based drilling fluid comprises a fluid having the formula R-CO-NH-R' -NH₂In an amount of 0.1 wt.% to 5 wt.%, based on the total weight of the oil-based drilling fluid.

Another aspect includes any of the preceding aspects, wherein the oil-based drilling fluid comprises the base oil in an amount of 10 wt.% to 20 wt.%, based on the total weight of the oil-based drilling fluid.

Another aspect includes any of the preceding aspects, wherein the oil-based drilling fluid comprises one or more wetting agents in an amount of 0.1 wt.% to 2 wt.%, based on the total weight of the oil-based drilling fluid.

Another aspect includes any of the preceding aspects, wherein the oil-based drilling fluid comprises one or more fluid loss control additives in an amount of 0.5 wt.% to 2 wt.% (based on the total weight of the oil-based drilling fluid).

Another aspect includes any of the preceding aspects, wherein the oil-based drilling fluid comprises one or more weighting additives in an amount of 50 wt.% to 90 wt.%, based on the total weight of the oil-based drilling fluid.

Another aspect includes any of the preceding aspects, wherein the layered double hydroxide comprises a myristate salt.

Another aspect includes any of the preceding aspects, wherein the layered double hydroxide comprises aluminum cations.

Another aspect includes any of the preceding aspects, wherein the layered double hydroxide comprises a magnesium cation.

Another aspect includes any of the preceding aspects, wherein the layered double hydroxide is a Mg/Al layered double hydroxide myristate.

Another aspect comprises any of the preceding aspects, further comprising mixing one or more additives selected from wetting agents, fluid loss control additives, and weighting additives with the base oil, the aqueous component, the emulsifier, and the rheology modifier.

Another aspect includes any of the preceding aspects, wherein the wellbore comprises a wellbore temperature greater than 300 ° f.

Another aspect includes any of the preceding aspects, wherein the wellbore comprises a wellbore pressure greater than 10,000 psi.

Another aspect includes any of the preceding aspects, wherein the wellbore comprises a wellbore pressure greater than 10,000 psi.

Another aspect includes any of the preceding aspects, wherein the surface temperature is 0 ℃ or less.

While the subject matter of the present disclosure has been described in detail and with reference to specific embodiments thereof, it should be noted that the various details described in the present disclosure should not be construed as implying that such details relate to elements that are essential components of the various embodiments described in the present disclosure, even though specific elements are shown in each of the figures accompanying this specification. Rather, the appended claims should be construed broadly and as merely representative of the respective scope of the various embodiments described in the disclosure. In addition, it will be apparent to those skilled in the art that various modifications and variations can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the present specification cover the modifications and variations of the various embodiments described, provided such modifications and variations fall within the scope of the appended claims and their equivalents.