Abstract: Internal breakers are given that break fluids viscosified with non-polymeric viscosifiers such as viscoelastic surfactants, inside formation pores. The breakers are polyols, for example natural and synthetic sugars, monoalcohols, and mixtures of the two. The sugars may be ketones and aldehydes. The sugars are also breaker aides for oxidizing agents used as breakers. Methods of using the breakers and breaker aides in oilfield treatment fluids are given.

Abstract: Delayed breakers are given that break viscoelastic surfactant fluids inside the pores of formations into which the fluids have been injected. The breakers comprise proteins, proteins that contain breakers, or cells that contain breakers. Proteins become breakers, and proteins and cells release breakers, due to a triggering mechanism that may be, for example, a change in temperature, pH, or salinity.

Abstract: A method of treating a subterranean formation penetrated by a wellbore utilizes a treating fluid formed from an aqueous solution of a water-soluble polymer. The treating fluid further contains a crosslinking agent and an optional delayed release alkaline additive. The delayed release alkaline additive may be at least one of urea, a urea derivative, a solid alkaline earth metal carbonate, a solid alkaline earth metal oxide and combinations of these. The treating fluid further includes an acidic pH adjusting agent used in an amount to provide the treating fluid with a pH of less than about 5. The treating fluid is then introduced into the formation.

Abstract: Methods for treating a formation penetrated by a wellbore which improves fluid loss control during treatment. In some aspects, the treatments include preparing an aqueous fluid including one or more water inert polymers and an optional viscosifier, injecting the aqueous fluid into the wellbore at a pressure equal to or greater than the formation's fracture initiation pressure, and thereafter injecting into the wellbore a proppant laden fluid at a pressure equal to or greater than the formation's fracture initiation pressure. The water inert polymer may be a polymer such as an emulsion polymer or a latex polymer. Some methods of the invention use a fluid which may have a normalized leak off coefficient (Cw/sqrt(K)) equal to or less than about 0.0022, 0.0014, or 0.0010. A conventional fluid loss additive may or may not be used in conjunction with the treatment fluid and/or the proppant laden fluid. The water inert polymer may or may not substantially enter formation pores.

Abstract: A method for shortening the shear recovery time of cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of an amphiphilic polymeric rheology enhancer containing at least one portion that is a partially hydrolyzed polyvinyl ester or partially hydrolyzed polyacrylate. The rheology enhancer also increases fluid viscosity and very low rheology enhancer concentration is needed. Preferred surfactants are betaines and quaternary amines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.

Abstract: A composition is formed from a polymeric acid precursor, such as polylactic acid (PLA), that is a least partially dissolved within a polymer dispersing solvent. An emulsion may be from polymeric acid precursor that is at least partially dissolved within a solvent and a liquid that is substantially immiscible with the solvent. In certain cases, the molecular weight of the polymeric acid precursor may be reduced in forming the solution. The solution may be used in treating a formation penetrated by a wellbore.

Abstract: Degradable material assisted diversion (DMAD) methods for well treatment, DMAD treatment fluids, and removable plugs for DMAD in downhole operations. A slurry of solid degradable material is injected into the well, a plug of the degradable material is formed, a downhole operation is performed around the plug diverter, and the plug is then degraded for removal. Degradation triggers can be temperature or chemical reactants, with optional accelerators or retarders to provide the desired timing for plug removal. In multilayer formation DMAD fracturing, the plug isolates a completed fracture while additional layers are sequentially fractured and plugged, and then the plugs are removed for flowback from the fractured layers. In DMAD fluids, an aqueous slurry can have a solids phase including a degradable material and a fluid phase including a viscoelastic surfactant. The solids phase can be a mixture of fibers and a particulate material.

Abstract: A wellbore treatment fluid is formed from an aqueous medium, a gas component, a viscosifying agent, and a surfactant. The surfactant is represented by the chemical formula: [R—(OCH2CH2)m—Oq—YOn]pX wherein R is a linear alkyl, branched alkyl, alkyl cycloaliphatic, or alkyl aryl group; O is an oxygen atom; Y is either a sulfur or phosphorus atom; m is 1 or more; n is a integer ranging from 1 to 3; p is a integer ranging from 1 to 4; q is a integer ranging from 0 to 1; and X is a cation. The fluid may be used in treating a subterranean formation penetrating by a wellbore by introducing the fluid into the wellbore. The fluid may be used in fracturing a subterranean formation penetrated by a wellbore by introducing the fluid into the formation at a pressure equal to or greater than the fracture initiation pressure.

Abstract: Compositions and methods are given for delayed breaking of viscoelastic surfactant gels inside formation pores, particularly for use in hydraulic fracturing. Breaking inside formation pores is accomplished without mechanical intervention or use of a second fluid. Oxidizing agents such as air, oxygen, persulfates, bromates, peroxides, and others are used. The break may be accelerated, for example with a free radical propagating species, or retarded, for example with an oxygen scavenger. In certain brines, for example bromide brines, certain zwitterionic viscoelastic fluid systems that can decarboxylate and that require an anion-containing co-surfactant undergo delayed degradation if oxygen is present, for example from fluid preparation or in a foam.

Abstract: Methods for treating a formation penetrated by a wellbore which improves fluid loss control during treatment. In some aspects, the treatments include preparing an aqueous fluid including one or more water inert polymers and an optional viscosifier, injecting the aqueous fluid into the wellbore at a pressure equal to or greater than the formation's fracture initiation pressure, and thereafter injecting into the wellbore a proppant laden fluid at a pressure equal to or greater than the formation's fracture initiation pressure. The water inert polymer may be a polymer such as an emulsion polymer or a latex polymer. Some methods of the invention use a fluid which may have a normalized leak off coefficient (Cw/sqrt(K)) equal to or less than about 0.0022, 0.0014, or 0.0010. A conventional fluid loss additive may or may not be used in conjunction with the treatment fluid and/or the proppant laden fluid. The water inert polymer may or may not substantially enter formation pores.

Abstract: Compositions and methods are given for delayed breaking of viscoelastic surfactant gels inside formation pores, particularly for use in hydraulic fracturing. Breaking inside formation pores is accomplished without mechanical intervention or use of a second fluid. Bromate oxidizing agents are used along with selected breaking activators for the bromate breaking compounds. Useful bromate breaking activators include acid-generating breaking activators, oxidizing sulfur containing breaking activators, and reducing agent breaking activators.

Abstract: Delayed breakers are given that break viscoelastic surfactant fluids inside the pores of formations into which the fluids have been injected. The breakers comprise proteins, proteins that contain breakers, or cells that contain breakers. Proteins become breakers, and proteins and cells release breakers, due to a triggering mechanism that may be, for example, a change in temperature, pH, or salinity.

Abstract: Compositions and methods are given for delayed breaking of viscoelastic surfactant gels inside formation pores, particularly for use in hydraulic fracturing. Breaking inside formation pores is accomplished without mechanical intervention or use of a second fluid. Acidic internal breakers such as sulfuric acid and nitric acid are used. The break may be accelerated, for example with a free radical propagating species, or retarded, for example with an oxygen scavenger.

Abstract: The invention provides an oilfield suspending friction reducer treatment composition fluid comprising from about 0.001 weight percent to about 0.5 weight percent of a drag reducing surfactant; at least one drag reducing enhancer selected from the group consisting of polymeric drag reduction enhancers, monomeric drag reduction enhancers, and mixtures thereof.

Abstract: An oilfield treatment method is given that uses fluids that contain surfactants used as foamers and/or viscosifiers such that the fluids pass the Alberta Energy and Utilities Board Directive 27 requirements for low toxicity to certain bioluminescent bacteria. Such fluids may be used in oilfield treatments, for example drilling and stimulation, near fresh water aquifers. The surfactants are certain non-ionic surfactants that are not aromatic, or certain amphoteric surfactants (that can be neutral), or certain zwitterionic surfactants, (in which both positive and negative charges are present in a single molecule so that the whole molecule is neutral).

Abstract: Disclosed are methods of treating wells and producing fluids from subterranean formations with treatment fluids comprising heteropolysaccharides. In particular, the invention relates to treatment and production methods with fluids containing a heteropolysaccharide, aqueous medium, and an electrolyte, wherein the fluids may further include a gas component, a surfactant and/or an organoamino compound. The fluids render significant drag reduction, good Theological properties and unusually rapid hydration rates.

Abstract: Delayed breakers are given that break viscoelastic surfactant fluids inside the pores of formations into which the fluids have been injected. The breakers comprise proteins, proteins that contain breakers, or cells that contain breakers. Proteins become breakers, and proteins and cells release breakers, due to a triggering mechanism that may be, for example, a change in temperature, pH, or salinity.

Abstract: A composition and method for improving the fluid efficiency of many oilfield treatments is given. The composition is a solid additive, in a viscosified fluid, in a size range small enough that it enters formation pores; it optionally bridges there to form an internal filter cake, and then decomposes to provide a breaker for the viscosifying system for the fluid. Examples of suitable additives include waxes, polyesters, polycarbonates, polyacetals, polymelamines, polyvinyl chlorides, and polyvinyl acetates. Degradation of the additive may be accelerated or delayed.

Abstract: A polycarbonate composition comprises chloride, sulfate, phosphate or a combination of two or more of the foregoing ionic species in an amount of zero to about 100 parts per billion based on the total weight of the composition; and phenol, carbonic diester, aromatic dihydroxy compound or combination of two or more of the foregoing organic compounds in an amount of zero to about 500 parts per million by weight based on the total weight of the composition; wherein the polycarbonate has a weight average molecular weight of about 40,000 to about 90,000 dalton as determined by gel permeation chromatography using polystyrene standards and a melt volume rate of about 1 to about 35 cm3/10 minutes when measured at about 300° C. with a force of about 1.2 kilograms.

Abstract: A method for shortening the shear recovery time of cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of an amphiphilic polymeric rheology enhancer containing at least one portion that is a partially hydrolyzed polyvinyl ester or partially hydrolyzed polyacrylate. The rheology enhancer also increases fluid viscosity and very low rheology enhancer concentration is needed. Preferred surfactants are betaines and quaternary amines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.