Abstract: Methods are provided for stimulation of hydrocarbon production from low permeability formations by hydraulic fracturing, acid fracturing, and hydraulic fracturing followed by gravel packing in a single operation. The methods use a first injected viscous pad made with low concentration uncrosslinked polymer to initiate and propagate the fracture and control fluid loss, followed by a second injected fluid gelled with a viscoelastic surfactant for carrying proppant or acid into the fracture.

Abstract: Liquid water soluble polymer suspensions in non-aqueous solvents are extremely stable over long periods of time with minimum separation of the solvent and no hard packing of the dispersed water soluble polymer. The suspensions enable a user to rapidly add the suspension to water, being mixed at low speeds, without the formation of lumps or fisheyes and without generating fugitive dust in the process. The suspensions are environmentally safe and biodegradable. Unlike many other liquid polymer suspensions, the suspensions exhibit minimal oil or grease upon dilution. They contain no surfactants that can add to the oil and grease determination. The suspensions and the fluids produced by diluting the fluids to a working concentration of the water soluble polymer exhibit low toxicity to marine organisms and to humans. The suspensions can be manufactured from ingredients suitable for use in personal care applications such as cosmetics, shampoos and the like.

Abstract: The present invention provides methods and compositions for treating subterranean zones penetrated by well bores utilizing environmentally safe viscous fluids. A method of the invention comprises the following steps. A viscous treating fluid composition is provided comprised of water, a viscosity increasing polymer and a water soluble delayed polymer breaker that comprises a mixture of sodium perborate tetrahydrate and a solubility increasing boron complex or ester forming compound. The viscous treating fluid composition is introduced into the subterranean zone wherein the viscous treating fluid is allowed to break into a thin fluid of reduced viscosity.

Abstract: Disclosed is a hydrophilic, water soluble polymer concentrate for addition to aqueous liquids to enhance the properties thereof, particularly to increase the viscosity or decrease the fluid loss of well drilling and servicing fluids, the concentrate comprising a hydrophobic, water insoluble liquid, an organophilic clay suspension agent, the water soluble polymer, and a stabilizing agent comprising one or more acids in an amount from about 0.001% to about 1.5%, one or more anionic surfactants in an amount from about 0.001% to about 1.0%, one or more nonionic surfactants in an amount from 0.001% to about 0.625% and, from about 0% to about 0.75% of one or more water soluble organic liquids, wherein the total concentration of the stabilizing agent is from about 0.1% to about 2.5%, these percentages being based on the weight of the concentrate.

Abstract: Methods of cementing in subterranean formations, cement compositions, and methods for making the compositions are provided. A cement slurry is passed into a subterranean formation, and a swelling agent is passed into the subterranean formation to reduce an amount of water flowing into the cement slurry. The swelling agent may be combined with a carrier fluid before being displaced into the subterranean formation. Alternatively, the swelling agent may be pre-mixed with the cement slurry to form a new cement composition, followed by displacing the cement composition into the subterranean formation. The swelling agent is present in an amount effective to, upon absorption of water and swelling to form a gel mass, substantially block the flow path of the water into the cement composition or reduce losses to low pore pressure intervals, thereby preventing the integrity of the cement composition from being compromised or lost to voidage, fractures, fissures, etc.

Abstract: A method of treating a well including injecting a thermally stable, substantially water-free well-treating fluid into the well, wherein the well-treating fluid comprises a polymer, a glycol compound, and a salt is disclosed. In another embodiment, a thermally stable, substantially water-free well fluid including a polymer, a diol compound, and a salt is disclosed.

Abstract: A method of fracturing a zone of a subterranean formation penetrated by a well bore is shown in which a gelable fracturing fluid is formed by combining an aqueous base fluid and a hydratable polymer. A transition metal crosslinker is added to the aqueous base fluid for crosslinking the hydratable polymer to form a gelled fluid of sufficient viscosity to facilitate fracturing of the formation. A proppant can also be added to the gelable fracturing fluid. The gelled fluid and proppant are then injected into the well bore and into contact with the formation under sufficient pressure to fracture the formation. The gelable fracturing fluid has incorporated therein a delayed release breaker comprising a complex multivalent chelating agent that is released slowly over a period of time to compete with the polymer for the transition metal crosslinker, thereby reducing the viscosity of the fluid.

Abstract: The present invention provides methods of treating subterranean zones penetrated by well bores in primary well cementing operations, well completion operations, production stimulation treatments and the like. The methods are basically comprised of introducing into the subterranean zone an aqueous well treating fluid comprised of water and a water soluble polymer complex fluid loss control additive.

Abstract: A well service fluid composition comprises a fracturing fluid and a gas hydrate inhibitor. Preferably, the gas hydrate inhibitor does not affect the function of the fracturing fluid and is present in an amount sufficient to control and/or minimize the formation of gas hydrates. The well service fluid composition is useful in hydraulic fracturing in which the composition is injected into a subterranean formation under sufficient pressure to initiate and propagate a fracture in the formation. The fracturing fluid may be subsequently recovered when the fracturing operation is completed.

Abstract: Liquid suspensions of particles in non-aqueous solvents are extremely stable over long periods of time with minimum separation of the solvent and no hard packing of the dispersed particles. The suspensions enable a user to rapidly add the suspension to water and to mix at low speeds without generating fugitive dust in the process. In addition, a liquid dispersion can provide an easy to use liquid containing higher concentrations of the active dispersed phase than can be accomplished by simply preparing an aqueous solution of the dispersed phase. Alternatively, highly water-soluble particles may also be suspended which have poor storage, freeze/thaw, or heat/cool stability. In some cases, liquid dispersions can yield controlled release of the dispersed phase because the dispersed phase is not in aqueous solution. The suspensions are environmentally safe and biodegradable and may be used in environmentally sensitive applications, such as for oil well treating fluids for offshore areas.

Abstract: A high temperture aqueous based zirconium (IV) crosslinked guar fracturing fluid having a pH from about 9 to about 12 includes a polymer solution and a zirconium (IV) crosslinking agent in an amount from about 0.1 PPTG to about 5 PPTG of the polymer solution. The polymer solution includes an aqueous fluid, natural guar gum in an amount from about 10 PPTG to about 100 PPTG of the aqueous fluid, a stabilizer in an amount from about 1 PPTG to about 50 PPTG of the aqueous fluid, a non-delayed alkaline buffer in an amount from about 1 PPTG to about 40 PPTG of the aqueous fluid, and a gelation delaying agent in an amount from about 0.25 PPTG to about 3.75 PPTG of the aqueous fluid, where those agents are combined to produce a fracturing fluid suitable to the purposes of hydraulically fracturing subterranean formations with static bottom-hole temperatures greater than 250° F.

Abstract: A well treatment fluid composition that comprises a carrier fluid and an amphoteric surfactant, and optionally a viscosifying agent and proppant, is well suited for use in fracturing coal beds to stimulate methane production. The composition preferably is a foam that comprises a gas such as nitrogen or air. Preferably, the surfactant has the formula R—NH2—(CH2)n—C(O)OX wherein R is a saturated or unsaturated alkyl group having from 6-20 carbon atoms, n is from 2-6, and X is hydrogen or a salt forming cation.

Abstract: The invention provides a method and fluid for drilling or servicing a well in a subterranean formation containing lost circulation zones or depleted, low pressure reservoirs. The fluid comprises an aqueous liquid having dispersed therein a polymer which increases the low shear rate viscosity of the fluid to the extent that the thixotropic index of the fluid is at least about 10 and a surfactant, and wherein the fluid contains less than about 15% by volume of aphrons preferably generated by the turbulence and pressure drop as the fluid exits the drill bit in the vicinity of the formation. The method of drilling a wellbore in a subterranean formation comprises continuously circulating, while drilling, such a drilling fluid.

Abstract: The present invention relates to a wellbore fluid comprising a particulate material composed of the reaction product of A) one or more water soluble organic compound having possessing a molecular weight of less than 30,000 and possessing at least two hydroxyl groups and B) any other organic compound(s) capable of forming acetal or hemiacetal cross-links with the hydroxyl groups of compound A. The invention relates also to the specific particulate material itself and to applications of the wellbore fluid of the invention for well processes such as drilling, under-reaming, completing, working over, sealing loss zones, sealing fractures, sealing cavities or other very high permeability conduits in a rock formation, or hydraulic fracturing to stimulate a hydrocarbon-producing zone.

Abstract: A method for enhancing the clean-up of a hydrocarbon-producing well, in which particles are pumped into the well to promote the recovery of the hydrocarbons. The particles are coated with a water-repellent composition to prevent, or at least minimize, the coating or adsorption of any gel polymer from the carrier fluid for the particles.

Abstract: A swellable polymer gel composition for use in subterranean formations. The composition comprises water, a water soluble polymer, a water soluble crosslinking system and a swelling agent. The crosslinking system may be either a redox system or a chelating system. The amounts of the polymer and the crosslinking system are effective to form a substantially uniformly reacted tri-dimensional gel structure. To the gel solution, is added a swelling agent in an amount sufficient to increase the volume of the gel a predetermined percentage. The swelling agent may be a natural or a synthetic agent. A strengthening agent may be added to increase the gel strength of the composition. The composition has numerous uses and is particularly useful in oil industry applications such as plugging wells, sealing casing leaks and reducing water production from water-bearing hydrocarbon formations.

Abstract: The invention provides an organic diacid anhydride-modified chitosan containing a polar additive comprising water soluble compounds containing one or more hydroxyl groups or one or more amino groups, including compounds containing both hydroxyl and amine groups, having a molecular weight less than about 2000, preferably less than about 1000. The invention also provides fluids useful in various well drilling and servicing operations comprising an alkaline aqueous liquid containing an organic diacid anhydride, chitosan, and the polar additive therein, as well as a method of drilling wells therewith.

Abstract: Methods are provided for fracturing subterranean formations using fluids having substantially reduced polymer loadings that have performance equivalent to conventional fluids. Reduced polymer loadings provide significant advantages such as reduced treatment costs and less damage to the fracture sand pack and surrounding subterranean formations.

Abstract: A method for promoting cement or concrete set on demand for concrete that has been chemically retarded by adding carbon fiber to the concrete, which enables it to become electrically conductive, sodium tartrate retardant, and copper sulfate which forms a copper tartrate complex in alkaline concrete mixes. Using electricity, the concrete mix anodically converts the retarding tartrate to an insoluble polyester polymer. The carbon fibers act as a continuous anode surface with a counter electrode wire embedded in the mix. Upon energizing, the retarding effect of tartrate is defeated by formation of the polyester polymer through condensation esterification thereby allowing the normal set to proceed unimpeded.

Abstract: A brine for use during drilling operations, preferably a completion brine, comprising an amount of a low molecular weight water-soluble organic compound effective to reduce the crystallization point of the brine. The low molecular weight water soluble organic compound can be a variety of compounds, with preferred compounds being ethylene glycol, tripropylene glycol bottoms, and combinations thereof. A method of lowering the crystallization point of the brine using a low molecular weight water soluble organic compound also is provided.

Abstract: This invention relates to a wellbore treatment fluid and a method of enhancing wellbore treatment fluids to increase efficiency and productivity of wells. More specifically this invention provides methods for enhancing the thermal stability of wellbore treatment fluids such as drill-in, completion, work-over, packer, well treating, testing, spacer, or hole abandonment fluids. The methods include providing a wellbore treatment fluid that includes a polyol selected from glycerol, glycols and polyglycols as well as a polysaccharide viscosifier. The fluid prepared for use in this invention find particularly advantageous use as a completion fluid and as a fluid loss pill. However, the fluid can include a wide variety of additional agents to modify the physical and chemical properties of the wellbore treatment fluid.

Abstract: This invention provides a water-free oil based fluid polymer suspension composition for use as a rheology modifier and fluid loss reducer in oil or gas well servicing fluids. It has been found that by using white medicinal oil as a carrier, high solids content and environmental friendly anhydrous fluidized polymer suspensions of xanthan gum, cellulose ethers, guar gum and derivatives thereof can be prepared. More specifically, in one aspect, an oil-based fluid polymer suspension (FPS) composition for use in oil or gas well servicing fluids is preferred containing: a) a hydrophilic polymer, b) an organophilic clay, c) a stabilizer, and d) a white medicinal oil having selected properties.

Abstract: It has been discovered that borate crosslinked fracturing fluid breaker mechanisms are improved by the inclusion of a polyol together with an enzyme. In fact, synergistic results may be achieved when both are used together as contrasted to the cases where each are used separately. Removing the borate ion from the crosslinked polymer reduces the pH of the fluid and in turn increases the activity of the enzyme. That is, once the pH is lowered, viscosity reduction (breaking) occurs by uncrosslinking of the polymer within the fracturing fluid, and by initiating or increasing activity of an enzyme breaker, if present. In one embodiment, the polyol has at least two cis-hydroxyl groups. In another embodiment, the polyols are monosaccharides such as glycerols and sugar alcohols, and may include mannitol, sorbitol, glucose, fructose, galactose, mannose, allose, etc. and mixtures thereof. Oligosaccharides and derivatives of monosaccharides and oligosaccharides are also useful.

Abstract: Herein is disclosed a well completion or stimulation fluid, comprising (i) a carrier fluid; (ii) a viscoelastic surfactant; and (iii) a fluid loss control additive (FLA) comprising at least one polymer and at least one crosslinker. The fluid may further comprise proppant or gravel, if it is intended for use as a fracturing fluid or a gravel packing fluid, although such uses do not require that the fluid comprise proppant or gravel. Also disclosed herein are methods of fracturing a subterranean formation, comprising (i) providing a fracturing fluid discussed above and (ii) injecting the fracturing fluid into the formation at a pressure sufficiently high to fracture the formation. In addition, disclosed herein are methods of gravel packing a wellbore, comprising (i) providing a gravel packing fluid discussed above and (ii) injecting the gravel packing fluid into the wellbore.

Abstract: The invention provides a method of fracturing, including the provision and use of a fracturing fluid suspension containing an effective amount of a solid particulate breaker material having delayed breaking or degradation characteristics, additionally including an amount of durable fibers and/or platelets sufficient to enhance wellbore solids, such as proppant, transport. In a preferred aspect, solid particulate matter, which comprises or is composed of a specified organic polymeric compound or composition having an average molecular weight of at least 10,000, or a mixture of such compounds or compositions, and which solid organic polymeric matter reacts or decomposes, as described, is combined in a fracturing fluid with or containing a specified gellant and proppant, to form a fracturing fluid suspension, and the suspension formed is pumped downwell and deposited as a gelled suspension in the subterranean formation, generally under fracturing conditions.

Abstract: Disclosed is a composition for and method of reducing the loss of fluid from well drilling, completion, or workover fluids during well drilling, completion, or workover operations, particularly for reducing or overcoming the lost circulation of drilling fluids. The composition comprises an aqueous liquid containing partially hydrated chitosan particles wherein the chitosan particles have been partially hydrated at a pH less than about 4.5, and wherein the aqueous liquid has a pH of at least about 6.5 such that any further solublizing of the chitosan is prevented. The aqueous liquid, preferably when mixed with a drilling, completion, or workover fluid, is effective in decreasing the loss of such fluids after introducing the partially hydrated chitosan-containing liquid or fluid into the flow passages in a well to which such fluids are being lost.

Abstract: The present invention provides oil based compositions and methods of using the compositions for temporarily sealing subterranean zones. The compositions are basically comprised of oil, a hydratable polymer, an organophilic clay, a water-swellable clay, and an acid soluble material such as calcium carbonate. These compositions will form a viscous gel when contacted with water. The gelled mass may then be dissolved with an acidic fluid, such as 15% hydrochloric acid.

Abstract: A method of preventing corrosion in pipelines comprising draining pipeline of all residual compounds, blowing through with nitrogen and rinsing with a corrosion inhibiting rinsing agent.

Abstract: A method of treating a subterranean formation using a well-treating fluid is provided, the subterranean formation penetrated by a wellbore, the method comprising preparing the well-treating fluid by admixing a fast-hydrating high-viscosity guar powder to a hydrating liquid to prepare the well-treating fluid; hydrating the guar powder; admixing a cross-linker to the well-treating fluid; and introducing the well-treating fluid to the wellbore at a temperature and a pressure sufficient to treat the subterranean formation. A product is also provided comprising a well-treating fluid for use in treating subterranean formations with the well-treating fluid comprising a hydrating liquid; a gelling agent, the gelling agent comprising a fast-hydrating high-viscosity guar powder; and a cross-linker.

Abstract: A method, and a product of such method, in which the manufacture of guar gum powder includes the additional step of extruding hydrated and flaked guar splits prior to grinding and drying. The extruding step may be included before or after the step of flaking the splits. The inclusion of the extruding step, along with the flaking step, has been found to create a guar gum powder product which has advantageous properties over the prior art. These advantageous properties include (1) increasing the hydration rate and the hydration acceleration rate of the guar gum powder without any corresponding change in particle size, and (2) providing a hydration acceleration rate that is less affected by cold temperatures.

Abstract: A method of treating a subterranean formation using a well-treating fluid is provided, the subterranean formation penetrated by a wellbore, the method comprising preparing the well-treating fluid by admixing a fast-hydrating high-viscosity guar powder to a hydrating liquid to prepare the well-treating fluid; hydrating the guar powder; admixing a cross-linker to the well-treating fluid; and introducing the well-treating fluid to the wellbore at a temperature and a pressure sufficient to treat the subterranean formation. A product is also provided comprising a well-treating fluid for use in treating subterranean formations with the well-treating fluid comprising a hydrating liquid; a gelling agent, the gelling agent comprising a fast-hydrating high-viscosity guar powder; and a cross-linker.

Abstract: This invention relates to a wellbore treatment fluid and a method of enhancing wellbore treatment fluids to increase efficiency and productivity of wells. More specifically this invention provides methods for enhancing the thermal stability of wellbore treatment fluids such as drill-in, completion, work-over, packer, well treating, testing, spacer, or hole abandonment fluids. The methods include providing a wellbore treatment fluid that includes a polyol selected from glycerol, glycols and polyglycols as well as a polysaccharide viscosifier. The fluid prepared for use in this invention find particularly advantageous use as a completion fluid and as a fluid loss pill. However, the fluid can include a wide variety of additional agents to modify the physical and chemical properties of the wellbore treatment fluid.

Abstract: A new stable liquid suspension containing non-soluble particles dispersed in a non-aqueous liquid medium having a concentration of a suspension aid and a method of making and use thereof.

Abstract: A process and composition are provided for permeability reduction in a hydrocarbon-bearing formation to improve hydrocarbon recovery therefrom. A moderately epichlorohydrin cross-linked, non-hydroxylpropylated starch is derived from high amylopectin waxy maize starch for use in drilling, workover and completion fluids. The starch is combined with xanthan gum and used in solutions of fresh water, non-saturated brine or saturated brine containing sized salt particles, typically sodium chloride, of various sizes, or sized calcium carbonate, or a combination of sized salt and sized calcium carbonate.

Abstract: Polymers are derivatized and then may be introduced into a wellbore, such as in a hydraulic fracturing treatment. A polymer may be a guar powder that is mixed with a organic solvent and derivatized using a derivatizing agent, such as sodium chloroacetate. The polymer is typically derivatized in bulk prior to introduction into the wellbore. The derivatized polymer may be hydrated and/or crosslinked prior to introduction into the wellbore.

Abstract: Methods are provided for fracturing subterranean formations using fluids having substantially reduced polymer loadings that have performance equivalent to conventional fluids. Reduced polymer loadings provide significant advantages such as reduced treatment costs and less damage to the fracture sand pack and surrounding subterranean formations.

Abstract: A guar gum powder product whose manufacturing process includes the additional step of extruding hydrated and flaked guar splits prior to grinding and drying. The extruding step may be included before or after the step of flaking the splits. The inclusion of the extruding step, along with the flaking step, has been found to create a guar gum powder product which has advantageous properties over the prior art. These advantageous properties include (1) increasing the hydration rate and the hydration acceleration rate of the guar gum powder without any corresponding change in particle size, and (2) providing a hydration acceleration rate that is less affected by cold temperatures.

Abstract: The invention provides well drilling and servicing fluids comprising an alkaline aqueous liquid containing chitosan, an anhydride, and an aldehyde therein. The invention further provides a method of drilling a well wherein there is circulated in the wellbore during drilling a drilling fluid comprising an alkaline aqueous liquid containing chitosan and an anhydride, and optionally an aldehyde therein.

Abstract: A chemical system and method to stop or minimize fluid loss during completion of wells penetrating hydrocarbon formations are provided. The inventions relates to formulating a highly stable crosslinked hydroxyethyl cellulose (HEC), control released viscosity reduction additives, and user friendly packaging. The chemical system contains a linear HEC polymer solution, a low solubility compound which slowly raises the fluid pH, a chelating agent which further increases the pH level beyond the equilibrium achievable by the low solubility compound, a metal crosslinker which crosslinks HEC at elevated pH, a crosslink delaying agent which allows fluid viscosity to remain low until the fluid reaches the subterranean formation, and optionally an internal breaker. The chemical additives are packaged as an integrated pallet and transported to a field location which allows operators to conveniently mix them before pumping.

Abstract: The present invention provides improved cross-linked well treating fluids and methods for preparing and using the fluids in treating wells such as fracturing subterranean zones therein. The improved cross-linked treating fluids comprise water, a galactomannan gelling agent, a cross-linking agent for cross-linking the galactomannan gelling agent, and a viscosity stabilizing agent selected from the group consisting of formaldehyde, formic acid, or mixtures thereof. The viscosity stabilizing agent alters the properties of the well treating fluids and enables them to retain their viscosity over prolonged periods of time when compared to prior well treating fluids.

Abstract: The present invention discloses a method of producing modified, derivatized chitosans which produce viscous aqueous liquids when dispersed (solublized) in compatible aqueous liquids. The method comprises reacting chitosan in an acidic solution with an aldehyde-group containing chemical modifier at an elevated temperature wherein the concentration of chitosan in the acidic solution and the reaction time at the elevated temperature are sufficient to produce a semi-solid gel. The preferred chemical modifier is one or more saccharides containing less than about 10 saccharide units, most preferably lactose. The preferred reaction temperature is greater than about 60° C., and the preferred concentration of chitosan is at least about 1.43% w/v. The invention also discloses the acidic chitosan-containing concentrates prepared by the method, and the viscous acidic fluids prepared by dispersing/solubilizing the concentrates in aqueous liquids.

Abstract: Methods are provided for fracturing subterranean formations using fluids having substantially reduced polymer loadings that have performance equivalent to conventional fluids. Reduced polymer loadings provide significant advantages such as reduced treatment costs and less damage to the fracture sand pack and surrounding subterranean formations.

Abstract: According to the present invention, a composition and method for hydraulically fracturing a subterranean formation is provided. The composition comprises an aqueous mixture of a hydrated polysaccharide, preferably a galactomannan gum, the hydrated polysaccharide having a plurality of bonding sites; a crosslinking agent for crosslinking the hydrated polysaccharide at the bonding sites at the conditions of the subterranean formation with a polyvalent metal ion to form a polyvalent metal crosslink, thereby increasing the viscosity of the hydrated polysaccharide; and a controlled solubility compound for releasing a chelating agent for controllably breaking the polyvalent metal crosslink and bonding with the polyvalent metal ion released by breaking the crosslink, thereby decreasing the viscosity of the hydrated polysaccharide.

Abstract: Improved high temperature, low residue viscous well treating fluids and methods of using the fluids are provided by the present invention. The improved viscous well treating fluids are basically comprised of water; a hydrated galactomannan gelling agent; a retarded cross-linking composition for buffering the treating fluid and cross-linking the hydrated galactomannan gelling agent comprised of a liquid solvent, an organotitanate chelate and a borate ion producing compound; and a delayed gel breaker.

Abstract: A wellbore service fluid comprising viscoelastic surfactants in combination with cross-linkable, preferably hydrophobically modified, water soluble polymers is described, particularly applicable to water control operations.

Abstract: The invention relates to the use of oil-soluble oleophilic organic liquid phases—flowable at temperatures of 0 to 10° C.—from the classes of corresponding monocarboxylic and/or polycarboxylic acid esters, carbonic acid esters, fatty alcohols and their oligoalkoxides and/or ethers as the at least predominant part of the liquid phase in storage-stable homogeneous mixtures with guar and/or water-soluble guar derivatives for their use in water-based borehole servicing fluids.

Abstract: A fracturing fluid and method is disclosed comprising an aqueous metal hydrated galactomannan gum, buffered to a pH of from about 9 to about 11, and using reduced amounts galactomannan gum. Further, the invention provides a metal ion source, such as borate, to crosslink the galactomannan gum polymer in subterranean fractures. In one embodiment a slowly dissolving slurried borate is used in pumping an alkaline fracturing fluid into a subterranean formation to increase production of hydrocarbons. In another embodiment, an encapsulated borate source is used. A chemical stabilizer optionally may be used.

Abstract: A process and composition are provided for permeability reduction in a hydrocarbon-bearing formation to improve hydrocarbon recovery therefrom. A moderately epichlorohydrin cross-linked, non-hydroxylpropylated starch is derived from high amylopectin waxy maize starch for use in drilling, workover and completion fluids. The starch is combined with xanthan gum and used in solutions of fresh water, non-saturated brine or saturated brine containing sized salt particles, typically sodium chloride, of various sizes, or sized calcium carbonate, or a combination of sized salt and sized calcium carbonate.

Abstract: Disclosed are oil-in-water emulsions containing an aqueous continuous phase, an emulsified oleaginous liquid, and an oligosaccharide mixture composed of sugar units selected from the group consisting of arabinose, mannose, galactose, glucose, xylose, and mixtures thereof, and which consists primarily of pentosans, hexosans, and mixtures thereof, containing from one to ten sugar units. The emulsions preferably also contain an alkaline earth metal oxide or hydroxide, preferably lime. The emulsions may also contain aphrons.

Abstract: An esterification process and the products resulting from it which achieves a mixture of secondary esters which are effectively used with invert drilling muds, the process involving the addition of one or more C.sub.1 -C.sub.5 carboxylic acids and one or more C.sub.3 -C.sub.22 olefins in the presence of an acid catalyst.