Abstract: Oil-based wellbore fluid in the form of an emulsion having a continuous phase containing an oil and, dispersed therein, a first dispersed liquid phase and a second separate dispersed liquid phase. The first dispersed liquid phase is a brine phase containing at least 5% by weight of a dissolved salt or a mixture of salts, and the second dispersed liquid phase is a polar organic liquid which is insoluble or sparingly soluble in the brine and contains the first dispersed liquid phase, but is soluble in pure water. The second dispersed liquid phase is in the form of droplets having an average diameter of not less than 5 microns.

Abstract: The use is described of oligoglycerol fatty acid esters, produced from (a) an acid component, selected from (a1) fatty acids of the general formula (I) R—COOH??(I) in which R stands for a saturated or unsaturated, branched or linear alkyl- or alkenyl radical with 7 to 21C atoms, and/or (a2) dicarboxylic acids and/or (a3) dimer fatty acids and/or (a4) oligomer fatty acids and/or (a5) hydroxy fatty acids with (b) a polyol component, which is selected from oligoglycerols or alkoxylates of oligoglycerols, as additive to oil-based drilling mud compositions to improve the lubricating effect of these mud systems.

Abstract: An invert emulsion wellbore fluid may include an oleaginous external phase; a non-oleaginous internal phase, wherein a ratio of the oleaginous external phase and non-oleaginous internal phase is less than 50:50; and an emulsifier stabilizing the oleaginous external phase and the non-oleaginous internal phase, wherein an average diameter of the non-oleaginous internal phase ranges from 0.5 to 5 microns.

Abstract: The present invention relates to a crosslinked glycerol or oligoglycerol ester which can be obtained by crosslinking a non-crosslinked glycerol or oligoglycerol ester which can be obtained by reacting an (A) acid phase comprising (a1) a fatty acid, (a2) a dicarboxylic acid, (a3) a dimeric fatty acid, (a4) an oligomeric fatty acid, (a5) a hydroxy fatty acid or (a6) a mixture of at least two thereof, with a (B) alcohol phase comprising (b1) monoglycerol, (b2) diglycerol, (b3) triglycerol, (b4) oligoglycerol made up of more than three glycerol units, (b5) an alkoxylate of glycerols (b1), (b2), (b3) or (b4), or (b6) a mixture of at least two thereof, forming a full or partial ester and crosslinking the full or partial ester by means of a crosslinking agent, wherein the crosslinking can take place during or after the formation of the full or partial ester.

Abstract: A wellbore fluid that includes an oleaginous continuous phase; a non-oleaginous phase; and a polymeric additive formed by mixing at least one lipophilic monomer and at least one crosslinking agent, wherein the at least one lipophilic monomer is at least one of an epoxide-functionalized derivative of at least one selected from soybean oil, linseed oil, rapeseed oil, cashew nut shell oil; perilla oil, tung oil, oiticia oil, safflower oil, poppy oil, hemp oil, cottonseed oil, sunflower oil, high-oleic triglycerides, triglycerides of euphorbia plants, peanut oil, olive oil, olive kernel oil, almond oil, kapok oil, hazelnut oil, apricot kernel oil, beechnut oil, lupine oil, maize oil, sesame oil, grapeseed oil, lallemantia oil, castor oil, herring oil, sardine oil, menhaden oil, whale oil, tall oil, and synthetic aliphatic or aromatic ethers, and the at least one crosslinking agent includes at least one selected from amines, alcohols, phenols, thiols, carbanions, carboxylates, and mixtures thereof is disclosed.

Abstract: Oligoglycerol esters of fatty acids, preferably of unsaturated fatty acids, can be used as thickeners in oil-based drilling mud compositions. The oligoglycerides are preferably employed in invert drilling muds, the oily phase of which contains paraffins.

Abstract: A method comprises providing a drilling fluid comprising: an aqueous fluid; and a microemulsion surfactant; and drilling a well bore in a subterranean formation comprising an oleaginous fluid using the drilling fluid, wherein the microemulsion surfactant forms a microemulsion with the oleaginous fluid within the well bore. In accordance with the method, the subterranean formation has a retained producibility greater than about 50%.

Abstract: The use of oligoglycerol fatty acid esters, prepared from (a) an acid component chosen from (a1) fatty acids of the general formula (I) R—COOH??(I) in which R represents a saturated or unsaturated, branched or linear alkyl or alkenyl radical having 7 to 21 C atoms, and/or (a2) dicarboxylic acids and/or (a3) dimer fatty acids and/or (a4) oligomer fatty acids and/or (a5) hydroxy fatty acids with (b) a polyol component which is chosen from oligoglycerols or alkoxylates of oligoglycerols, as an additive in water-based drilling mud compositions for improving the lubricating action of these mud systems, is described.

Abstract: A drilling fluid comprising: a non-ionic surfactant including: a branched alcohol ethoxylate and/or a capped alcohol ethoxylate; and a detergent builder.

Abstract: The lubricity of a drilling fluid or a completion fluid may be increased by incorporating into the fluid a water-soluble or water-dispersible salt of a sulfonated (sulfated) vegetable oil or a derivative thereof, such as a sulfonated (sulfated) castor oil. Suitable derivatives include the sodium, potassium, calcium, magnesium or ammonium salt. A non-ionic or anionic surfactant which is capable of enhancing the solubility of the salt may further be incorporated into the drilling fluid or completion fluid.

Abstract: The present invention relates to glycerol based drilling fluids. In particular, the invention relates to drilling fluids comprising a 95-20 volume % glycerol/water solution capable of stabilizing water-sensitive formations during drilling and the use of such solutions for drilling a well having water-sensitive formations.

Abstract: A drilling fluid comprising: a non-ionic surfactant including at least one of a branched alcohol ethoxylate and a capped alcohol ethoxylate, a detergent builder and a viscosifier.

Abstract: Fluids and associated methods useful in subterranean applications are provided. More particularly, methods of reducing drill string sticking are provided, which include: providing a spotting fluid composition comprising a water insoluble external phase fluid, a water soluble internal phase fluid, and an ether carboxylic acid emulsifying agent; introducing the spotting fluid to the vicinity of a desired portion of a drill string; and allowing the spotting fluid to interact with a portion of material surrounding the desired portion of the drill string spotting fluid. Compositions are provided that may be useful in subterranean applications for addressing, among other things, drill string sticking problems. Additional optional components may be used, such as viscosifiers, weighting agents, and wetting agents.

Abstract: Fluids and associated methods useful in subterranean applications are provided. Compositions are provided that may be useful in subterranean applications for addressing, among other things, drill string sticking problems. More particularly, spotting fluid compositions are provided having a water insoluble external phase fluid; a water soluble internal phase fluid; and an ether carboxylic acid emulsifying agent. Additional optional components may be used, such as viscosifiers, weighting agents, and wetting agents.

Abstract: A thermal insulation composition comprising: aqueous base; one or more primary viscosifier comprising a quantity of clay; and, an amount of one or more polymeric viscosifier comprising sulfonate moiety.

Abstract: A water-based drilling fluid and method of using same are presented in this disclosure, which fluid is used in drilling wells through a formation containing a shale that swells in the presence of water. The drilling fluid comprises an aqueous based continuous phase; a weighting material; and a shale hydration inhibition agent (SHIA) selected from the group consisting of propylamine derivatives, hydrogenated poly(propyleneimine) dendrimers (HPPID), and polyamine twin dendrimers (PTD). In some embodiments, the SHIA of this disclosure is not hydrolyzed at a temperature in the range of from about 100° F. to about 500° F. The drilling fluid may further comprise a fluid loss control agent, an encapsulating agent, other additives, and combinations thereof. A method of reducing shale swelling during wellbore drilling is also described. The method comprises circulating in the subterranean well a water-based drilling fluid comprising an aqueous based continuous phase, a weighting material, and a SHIA.

Abstract: A method of treating a well that includes selectively emplacing a fluid loss pill into the well, wherein the fluid loss pill includes at least one of diethylene glycol, triethylene glycol, and tetraethylene glycol, and wherein the at least one of diethylene glycol, triethylene glycol, and tetraethylene glycol reacts with a calcium brine present in the well to form a plug is disclosed.

Abstract: This invention relates to improved lubrication in drilling and completion fluids used in subterrane drilling for oil and gas. The addition of zinc dialkyl dithiophosphate (ZDDP) acts as a lubricant, an enhancer to other lubricants and rate of penetration enhancer.

Abstract: A drilling fluid comprising: a non-ionic surfactant including at least one of a branched alcohol ethoxylate and a capped alcohol ethoxylate, a detergent builder and a viscosifier.

Abstract: Wellbore fluids containing poly(trimethylene ether)glycols are provided. The wellbore fluids can provide enhanced functionality, improved cost effectiveness, and reduced environmental impact as compared to conventional wellbore fluids.

Abstract: Compositions comprising: (A) at least one surfactant of the general formula (I) (R1—[(O—(CH2)2)x1(O—CH(CH3)CH2)x2]O)kP(?O)(OH)3-k??(I) wherein the sequence of the alkyleneoxy units is arbitrary, each R1 independently represents a moiety selected from the group consisting of linear and branched C12-C22-alkyl, C12-C22-alkenyl, C12-C22-alkynyl, (C11-C21-alkyl)carbonyl, (C11-C21-alkenyl)carbonyl and (C11-C21-alkynyl)carbonyl, k represents 1 or 2 and x1 and x2 each independently represent an integer of 0 to 20, the sum of x1 and x2 being a number of 1 to 20; and (B) at least one thickener comprising at least two hydrophobic groups R2 which are linked to one another via a bridging hydrophilic group (?), wherein each R2, independently represents a moiety selected from the group consisting of C8-C32-alkyl, C8-C32-alkenyl, C8-C32-alkynyl, cycloalkyl, aryl, and aryl-C1-C32-alkyl, which in each case may have up to 3 hydroxyl substituents; wherein the composition has a pH which is viscosity-dependent.

Abstract: A water-based polymer drilling fluid, containing effective quantities of surfactants having HLB numbers equal to or greater than approximately 7, emulsifies oil and bitumen contained in oil sand cuttings, resulting in the oil and bitumen being dispersed into the mud as an emulsion. This eliminates or significantly reduces the ability of the oil, bitumen, and cuttings to clog the well or stick to drill string components when drilling a well through oil-bearing sands, particularly sands containing highly viscous oil or bitumen. The emulsification process separates the sand particles from the oil and bitumen, such that the sand particles can be removed when the mud is run through a conventional shale shaker or other suitable apparatus.

Abstract: In various aspects are provided a microfluidic and/or nanofluidic sensor that can provide an indication of the reliability of its measurement of the presence of an analyte in a sample under investigation, an analyte concentration in the sample under investigation, or both. The provided sensors, microfluidic devices, and methods of analyte detection, utilize two transduction mechanisms from the same molecule to determine analyte presence, analyte concentration, or both. An analyte sensing molecule is used that can provide both an optical signal and electrochemical signal when an analyte is recognized by an analyte binding portion of the sensing molecule.

Abstract: The invention concerns modified hydrophobic polyelectrolytes by amide formation of a hydrophilic skeleton by n-alkylamines whereof the alkyl chain comprises 6 to 22 carbon atoms. Preferably, the amide formation is obtained by di-n-dodecylamine. The hydrophilic skeleton is preferably a sodium polyacrylate or polyacrylic acid corresponding to a statistical acrylate-AMPS copolymer. Said polymers can be used for stabilizing direct or invert emulsions likely to be destabilized or inverted by a modification in the degree of salinity of the aqueous phase or a pH modification. The invention is particularly useful for stabilizing oil drilling fluids or the like in particular drilling, fracturation, acidification or completion fluids.

Abstract: Among the methods provided is a method of drilling a subterranean well with an invert emulsion fluid comprising: providing an invert emulsion fluid formed by combining components that comprise: an oil-based continuous phase; an aqueous discontinuous phase; and a polar hydrophobic additive that comprises a polar hydrophobe, wherein the polar hydrophobic additive may substantially increases the yield point, the low-shear yield point, or both of the invert emulsion fluid relative to a fluid without a polar hydrophobic additive while limiting the change in the plastic viscosity to no more than about 35% of the change in the property with the largest increase; and placing the invert emulsion fluid in a subterranean formation.

Abstract: A new class of secondary emulsifying agents for use in inverted mud and other inverted system is disclosed and method for making and using same.

Abstract: A new class of winterizing compositions are disclosed including a winterizing agents being a compound of general formula Z(R1)m, where Z is a polyol having between 5 and 30 carbon atoms, R1 is a carbyl group having between about 10 and about 40 carbon atoms, and where m is an integer having the value of 1 or 2, when m is 2, R1 can be the same or different and one or more carbon atoms of R1 can be replaced by B, N, O, Si, P, S, Ge and/or mixtures thereof and one or more of the hydrogen atoms in R1 can be replaced by F, Cl, Br, I, CONR22, COOR2, OR2, NR22, SR2, PR22, and/or mixtures thereof and where R2 can be a hydrogen atom, alkyl, aryl, alkylaryl or arylalkyl group having between 1-20 carbon atoms where one or more carbon or hydrogen atoms can be replaced as set forth for R1.

Abstract: A water based drilling fluid contains as additive one or more alkyl ethoxylates having the formula RO(CH2CH2O)nH; wherein: R is a C16-22alkyl group (preferably R is aliphatic and more preferably R is linear), and n is an integer in the range 2-30. The fluid further contains one or more viscosifying agents, and is substantially clay-free.

Abstract: The present invention relates to bridging agents for use in subterranean formations, to well drill-in and servicing fluids comprising such bridging agents, and to methods of using such bridging agents and well drill-in and servicing fluids in subterranean drilling operations. An example of a well drill-in and servicing fluid of the present invention comprises a viscosified fluid, a fluid loss control additive, and a bridging agent comprising a degradable material.

Abstract: The invention provides an oil-based wellbore fluid in the form of an emulsion which comprises a continuous phase comprising an oil and, dispersed therein, a first dispersed liquid phase and a second separate dispersed liquid phase, the first dispersed liquid phase being a brine phase, and the second dispersed liquid phase comprising a polar organic liquid, said polar organic liquid being insoluble or sparingly soluble in the brine comprising said first dispersed liquid phase, but being soluble in pure water. There is also provided a method of carrying out a wellbore operation, which includes the steps of (a) introducing into a wellbore a wellbore fluid of the invention; (b) allowing a filter-cake to form; and subsequently (c) allowing a further fluid to come into contact with the filter-cake, said further fluid having a level of salinity which is lower than the level of salinity of said first dispersed liquid phase, and being such that said polar organic liquid is soluble therein.

Abstract: Treatments fluids relating to the hydrolysis of water-hydrolysable materials are provided. In one embodiment, provided is a treatment fluid that comprises an aqueous liquid, a water-miscible solvent, and a water-hydrolysable material. Also provided is a hydrolysis retarder composition that comprises an aqueous liquid and a water-miscible solvent.

Abstract: A method of cleaning a wellbore prior to the production of oil or gas, wherein the wellbore has been drilled with an invert emulsion drilling mud that forms an invert emulsion filter cake is disclosed. The method may include circulating a breaker fluid into the wellbore, where the breaker fluid includes a non-oleaginous internal phase and an oleaginous external phase, where the non-oleaginous phase includes a water soluble polar organic solvent, a hydrolysable ester of a carboxylic acid, and a weighting agent, and the oleaginous external phase includes an oleaginous fluid and an emulsifier, and where the hydrolysable ester is selected so that upon hydrolysis an organic acid is released and the invert emulsion of the filter cake breaks.

Abstract: Of the many compositions and methods provided herein, an example method includes a method of treating a subterranean formation that comprises combining components comprising water and a density-matched suspension to prepare a treatment fluid, wherein the density-matched suspension comprises a suspending liquid and a solid particle suspended in the suspending liquid, and introducing the treatment fluid into a well bore. An example composition includes a suspension that comprises a suspending liquid comprising a hydrophobic liquid, wherein the hydrophobic liquid hydrolyzes when placed in contact with an aqueous fluid to form hydrophilic products, and a solid particle suspended in the suspending liquid, wherein the suspension is a density-matched suspension.

Abstract: Latex additives, methods for treating latex additives, drilling fluid systems, and lost circulation pills comprising the latex additives, the latex additive comprising latex particles having a particle size distribution before aging comprising an average particle diameter of about 1 micron or less; and a quantity of one or more water soluble oxygenated organic molecules comprising two or more oxygen atoms effective to maintain substantially the same particle size distribution before and after freezing the latex additive.

Abstract: A method of insulating pipeline bundles used in recovering hydrocarbons from wells is disclosed. A polymeric substance, such as an orthophosphate ester, is injected into the annulus between a carrier pipe and the hydrocarbon conveying tubulars. A ferric salt, such as ferric sulphate, may be added as a gelling agent. The mixture results in a gel having a dynamic viscosity of greater than (1000) PaS. The gel insulates the inner hydrocarbon-conveying tubulars from the surrounding seawater thus helping to maintain the relatively high temperature therewithin. This in turn reduces the likelihood for chemicals, such as hydrates, to be precipitated out of the oil phase.

Abstract: A well servicing composition containing an aqueous phase and an oil phase and an ether carboxylic acid of the formula: RO(CH2CH2O)x(CH2CHR1O)yCH2—COOX wherein, R is a saturated or unsaturated, branched or unbranched alkyl or alkenyl group containing 6 to 22 carbon atoms, x is a number from 1 to 20 and y is 0 or a number from 1 to 20, provided that the sum of x and y is at least 1 and at most 25, R1 is an alkyl group containing 1 to 4 carbon atoms and X comprises at least one member selected from the group consisting of a hydrogen atom, monovalent cations and polyvalent cations.

Abstract: The present invention provides a method of forming a viscosified treatment fluid comprising: providing a treatment fluid that comprises water and a gelling agent; contacting the treatment fluid with a boronic acid crosslinking agent so as to form a crosslinked gelling agent, wherein the boronic acid crosslinking agent comprises a compound having the formula: The present invention also provides methods of crosslinking gelling agent molecules, methods of treating a subterranean formation, methods of reusing viscosified treatment fluids, methods of fracturing subterranean formations, and methods of placing a gravel pack in subterranean formations. The present invention also provides boronic acid crosslinking agents and viscosified treatment fluids that comprise crosslinked gelling agents, the crosslinked gelling agent being formed from a reaction comprising a gelling agent and a boronic acid crosslinking agent.

Abstract: This invention relates to improved lubrication in drilling and completion fluids used in subterrain drilling for oil and gas. The addition of zinc dialkyl dithiophosphate (ZDDP) acts as a lubricant, an enhancer to other lubricants and rate of penetration enhancer.

Abstract: Nanoemulsions have been discovered to be useful to the oil field. More particularly water-in-oil (W/O), oil-in-water (O/W) and other classes of nanoemulsions have found beneficial application in drilling, completion, well remediation and other oil and gas industry related operations. Additionally, nanoemulsions may reduce friction pressure losses, as well as reduce subsidence of solid weight material during oil and gas operations. New preparation methods for nanoemulsions have also been discovered.

Abstract: A method of reducing wear in a cutting head of a tunnel boring machine, by means of the addition at the cutting head of a foamed aqueous liquid composition, which comprises a foaming agent and a lubricant, the lubricant being selected from the group consisting of high molecular weight polyethylene oxides and bentonite. Preferred foaming agents are anionic and nonionic surfactants. Wear rates of cutting elements of TBMs boring in hard rock are considerably reduced. A wear-reducing foamable concentrate is also described.

Abstract: Diesel oil-based invert emulsion drilling fluids having fragile gel properties and improved performance. Methods are also disclosed for drilling, running casing, cementing, and/or producing hydrocarbons in a subterranean formation.

Abstract: Single phase microemulsions improve the removal of filter cakes formed during drilling with invert emulsions. The single phase microemulsion removes oil and solids from the deposited filter cake. Optionally, an acid capable of solubilizing the filter cake bridging particles may also be used with the microemulsion. In one non-limiting embodiment the acid may be a polyamino carboxylic acid. Skin damage removal from internal and external filter cake deposition can be reduced.

Abstract: The invention relates to a borehole treatment composition containing an aqueous phase and a non-aqueous oil phase, emulsifiers and, where appropriate, further customary additives, the non-aqueous oil phase containing at least one of a) paraffins having from 5 to 22 carbon atoms; and b) internal olefins having from 12 to 30 carbon atoms in the molecule; in the form of a blend with c) carboxylic esters of the formula R—COO—R?, where R stands for a linear or branched, saturated or unsaturated alkyl radical having from 15 to 25 carbon atoms and R? denotes a saturated, linear or branched alkyl radical having from 3 to 22 carbon atoms. The ratio of the toxicity of internal olefins of chain length C16/C18 (standard IO) to the toxicity of the constituents of the non-aqueous oil phase, in each case measured by the Leptocheirus plumulosus acute, static 96 hour/10 day sediment toxicity test (in accordance with ASTM E 1367-92 & EPA/600/R-94/025, Section 11), is less than 1.

Abstract: A method for drilling, running casing in, and/or cementing a borehole in a subterranean formation without significant loss of drilling fluid is disclosed, as well as compositions for use in such method. The method employs a drilling fluid comprising a fragile gel or having fragile gel behavior and providing superior oil mud rheology and overall performance. The fluid is especially advantageous for use in deep water wells because the fluid exhibits minimal difference between downhole equivalent circulating density and surface density notwithstanding differences in drilling or penetration rates. When an ester and isomerized olefin blend is used for the base of the fluid, the fluid makes an environmentally acceptable and regulatory compliant invert emulsion drilling fluid. The fluid preferably contains no organophilic clays.

Abstract: A method of reducing the viscosity of invert emulsions and oil-based drilling fluids and well service fluids comprising such emulsions over a broad temperature range is disclosed. The method comprises adding to said invert emulsions of the invention a non-ionic surfactant alone or in combination with a co-thinner having the formula: R??—(C2H4O)n(C3H6O)m(C4H8O)k—H where R?? is a saturated or unsaturated, linear or branched, alkyl radical having about 8 to about 24 carbon atoms, n is a number ranging from about 1 to about 10, m is a number ranging from about 0 to about 10, and k is a number ranging from about 0 to about 10. The non-ionic surfactant is a reaction product of ethylene oxide, propylene oxide and/or butylene oxide with C10-22 carboxylic acids or C10-22 carboxylic acid derivatives containing at least in position 9/10 and/or 13/14 structural units of general formula (I) where R1 is a hydrogen atom or an OH group or a group OR2.

Abstract: Multi-component additive for incorporation into a drilling fluid, and a drilling fluid system comprising said multi-component additive. The additive preferably comprises three primary components: (1) a rate of penetration enhancer, namely one of a number of synthetic (non-toxic) ester-based or olefin-based oils as a carrier for other additives, such as surfactants; (2) a lubricant, namely one or more of a number of chlorinated waxes, chlorinated olefins, and plant based fatty acids; and (3) a clay inhibitor/stabilizer, such as a polyglycol. Preferably, the three components are pre-mixed in a single container, for ease in use in adding to a drilling fluid system. The additive may be incorporated into a drilling fluid system at a shore based facility, and the “liquid mud” transported to a drilling rig; or the additive may be brought to the drilling rig and incorporated into a drilling fluid system on site.

Abstract: A completion and workover fluid composition comprising, water and at least one rheology modifier and/or fluid loss control agent, and at least one other ingredient selected from the group consisting of inorganic salts, shale inhibitors, corrosion inhibitor, biocide, defoamers and finely divided solids particles (e.g., bentonite, attapulgite, sepiolite, calcium carbonate, etc.), depending upon the desired attributes, wherein the rheology modifier and/or the fluid loss control agent is an ethoxylated raw cotton linters or a modified ethoxylated raw cotton linters. The ethoxylated raw cotton linters provides comparable or better rheology and viscosity properties compared to high molecular weight commercial HECs made from purified cotton linters. These ethoxylated raw cotton linters derivatives are suitable for applications in oil-well servicing fluids, particularly to enhance functional properties of completion and workover fluids used during oil-well drilling operations.

Abstract: Drilling fluids, drilling lubricants for such drilling fluids, and methods of drilling wells, particularly oil and/or gas wells using such drilling fluids. The inclusion of lubricants affords lubrication in drilling fluids in which the lubricant compatibility and/or performance may be adversely affected by other components of the drilling fluid, particularly divalent cations such as calcium, formate salts or highly alkaline components such as alkali silicate.

Abstract: Methods for drilling, running casing in, and/or cementing a borehole in a subterranean formation without significant loss of drilling fluid are disclosed, as well as compositions for use in such methods. The methods employ drilling fluids comprising fragile gels or having fragile gel behavior and providing superior oil mud rheology and overall performance. The fluids are especially advantageous for use in offshore wells because the fluids exhibit minimal differences between downhole equivalent circulating densities and surface densities notwithstanding differences in drilling or penetration rates. When an ester and isomerized olefin blend is used for the base of the fluids, the fluids make environmentally acceptable and regulatory compliant invert emulsion drilling fluids.

Abstract: Methods for drilling, running casing in, and/or cementing a borehole in a subterranean formation without significant loss of drilling fluid are disclosed, as well as compositions for use in such methods. The methods employ drilling fluids comprising fragile gels or having fragile gel behavior and providing superior oil mud rheology and overall performance. The fluids are especially advantageous for use in offshore wells because the fluids exhibit minimal differences between downhole equivalent circulating densities and surface densities notwithstanding differences in drilling or penetration rates. When an ester and isomerized olefin blend is used for the base of the fluids, the fluids make environmentally acceptable and regulatory compliant invert emulsion drilling fluids.