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: A well treatment fluid and method uses an organic peroxide. An activator embodiment can lower an effective concentration of the peroxide to break the fluid. A weight ratio of activator:organic peroxide can be at least about 1:20 in one well treatment fluid embodiment. A peroxyester breaker embodiment can be used in a well treatment fluid and method. A breaker delay agent embodiment can control the polymer break window in a well treatment fluid and method using an organic peroxide. A breaker package embodiment used in a well treatment fluid and method can include an organic peroxide and an amine breaker delay agent having the formula RR1NR2 wherein R, R1 and R2 are independently selected from hydrogen, alkyl, hydroxyalkyl, and combinations thereof.

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: 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: Methods of improving shear recovery time of viscoelastic surfactant fluid systems are described, one method involving providing a viscoelastic surfactant fluid system comprising a major portion of a surfactant and a rheology enhancer in a concentration sufficient to shorten shear recovery time of the fluid system compared to shear recovery time of the fluid system absent the rheology enhancer, the rheology enhancer selected from aromatic sulfonates having a molecular weight of at least 500; and injecting the fluid system down a well. The rheology enhancer may be a lignosulfonate derived from wood pulping. Viscoelastic surfactant systems including the rheology enhancer are also described.

Abstract: A well treatment fluid and method uses an organic peroxide. An activator embodiment can lower an effective concentration of the peroxide to break the fluid. A weight ratio of activator:organic peroxide can be at least about 1:20 in one well treatment fluid embodiment. A peroxyester breaker embodiment can be used in a well treatment fluid and method. A breaker delay agent embodiment can control the polymer break window in a well treatment fluid and method using an organic peroxide. A breaker package embodiment used in a well treatment fluid and method can include an organic peroxide and an amine breaker delay agent having the formula RR1NR2 wherein R, R1 and R2 are independently selected from hydrogen, alkyl, hydroxyalkyl, and combinations thereof.

Abstract: Methods of improving shear recovery time of viscoelastic surfactant fluid systems are described, one method involving providing a viscoelastic surfactant fluid system comprising a major portion of a surfactant and a rheology enhancer in a concentration sufficient to shorten shear recovery time of the fluid system compared to shear recovery time of the fluid system absent the rheology enhancer, the rheology enhancer selected from aromatic sulfonates having a molecular weight of at least 500; and injecting the fluid system down a well. The rheology enhancer may be a lignosulfonate derived from wood pulping. Viscoelastic surfactant systems including the rheology enhancer are also described.

Abstract: This invention relates to compositions and methods for treating subterranean formations, in particular, oilfield stimulation compositions and methods using water-in-water polymer emulsions to uniformly dissolve a rheologically active polymer, such as a thickener or friction reducer, in the treatment fluid. The emulsions have a low viscosity and are easily pumped for mixing into a treatment fluid, where upon dilution with an aqueous medium, the polymer is easily hydrated without forming fish-eyes. The partitioning agent in the water-in-water emulsion does not generally affect the rheology of the treatment fluid. The invention also relates to further processing of the emulsion by wet grinding, high shear mixing and/or heating to enhance the hydration rate in the preparation of the well treatment fluid.

Abstract: This invention relates to compositions and methods for treating subterranean formations, in particular, oilfield stimulation compositions and methods using water-in-water polymer emulsions to uniformly dissolve a rheologically active polymer, such as a thickener or friction reducer, in the treatment fluid. The emulsions have a low viscosity and are easily pumped for mixing into a treatment fluid, where upon dilution with an aqueous medium, the polymer is easily hydrated without forming fish-eyes. The partitioning agent in the water-in-water emulsion does not generally affect the rheology of the treatment fluid. The invention also relates to further processing of the emulsion by wet grinding, high shear mixing and/or heating to enhance the hydration rate in the preparation of the well treatment fluid.

Abstract: An exemplary bridge includes an arch unit. The arch unit includes a first abutment and a second abutment, a deck extending between the first and second abutments, a pair of asymmetrical arches, and a plurality of suspender members 3 attached between the arches and the deck. The first and second abutments are spaced apart from each other at a predetermined distance. The asymmetrical arches are juxtaposedly arranged between and supported by the first and second abutments. Each of the asymmetrical arches includes a first arch foot portion mounted on the first abutment, a parabolic portion proximate to the first arch foot portion, a catenary portion proximate to the parabolic portion, and a second arch foot portion proximate to the catenary portion mounted on the second abutment.

Abstract: Methods comprising preparing an aqueous mixture of an anionic polymer, a charge screening surfactant, and a borate crosslinker, wherein the mixture has a conductivity less than 10 mS/cm, injecting the mixture down a wellbore, and gelling the mixture. An embodiment of the aqueous mixture can also include tetramethylammonium chloride as a clay stabilizer and a metal crosslinker such as a complex of zirconium and an amino acid ligand system. An embodiment can effectively provide borate crosslinking of an anionic polymer in a low-ionic-strength fluid system, without sacrificing ultimate gel strength or thermal persistence of the metal crosslinked polymer.

Abstract: Disclosed are compositions and methods for treating subterranean formations, in particular, oilfield stimulation compositions and methods using polymer viscosified fluid crosslinked with metal complexes with amino and/or phosphonic acids to provide an increased crosslinking temperature and a low pH sensitivity. The metal complexes can be used with borate crosslinkers to provide continuous viscosification as the temperature is increased.

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 for shortening the shear recovery time of cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of a rheology enhancer selected from partially hydrolyzed polyvinyl ester and partially hydrolyzed polyacrylates. 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: Well treatment is disclosed that includes injecting a well treatment fluid with insoluble polyol polymer such as polyvinyl alcohol (PVOH) dispersed therein, depositing the insoluble polymer in the wellbore or an adjacent formation, and thereafter dissolving the polymer by reducing salinity and/or increasing temperature conditions in the environment of the polymer deposit. The method is disclosed for filter cake formation, fluid loss control, drilling, hydraulic fracturing and fiber assisted transport, where removal of the polyol at the end of treatment or after treatment is desired. The method is also disclosed for providing dissolved polyol as a delayed breaker in crosslinked polymer viscosified systems and viscoelastic surfactant systems. Also disclosed are well treatment fluids containing insoluble amorphous or at least partially crystalline polyol, and a PVOH fiber composition wherein the fibers are stabilized from dissolution by salinity.

Abstract: Composition and method for shortening the shear recovery time of cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of a co-gelling agent selected from triblock oligomeric compounds having hydrophilic (for example polyether) and hydrophobic (for example alkyl) portions. The co-gelling agent also increases fluid viscosity and very low co-gelling agent 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 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 method for increasing the rate of shear rehealing of fluids made with cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of a polymeric rheology enhancer selected from polypropylene glycols and block copolymers of polypropylene glycol and polyethylene glycol. For applications in which rapid shear rehealing is required, the rheology enhancer allows fluids to be made and used at lower viscoelastic surfactant concentrations. Preferred surfactants are betaines and quaternary amines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.

Abstract: Methods of improving shear recovery time of viscoelastic surfactant fluid systems are described, one method involving providing a viscoelastic surfactant fluid system comprising a major portion of a surfactant and a rheology enhancer in a concentration sufficient to shorten shear recovery time of the fluid system compared to shear recovery time of the fluid system absent the rheology enhancer, the rheology enhancer selected from aromatic sulfonates having a molecular weight of at least 500; and injecting the fluid system down a well. The rheology enhancer may be a lignosulfonate derived from wood pulping. Viscoelastic surfactant systems including the rheology enhancer are also described.

Abstract: A method for increasing the rate of shear rehealing of fluids made with cationic, zwitterionic, and amphoteric viscoelastic surfactant fluid systems by adding an effective amount of a rheology enhancer package containing, for example a polyethylene glycol-polypropylene glycol block copolymer and a polynaphthalene sulfonate. The rheology enhancer package allows viscoelastic surfactant fluids to be used at lower viscoelastic surfactant concentrations in certain applications, for example certain oilfield treatments, for example fracturing and gravel packing. Preferred surfactants are betaines and quaternary amines.