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 well treatment by forming a temporary plug in a fracture, a perforation, a wellbore, or more than one of these locations, in a well penetrating a subterranean formation is provided, in which the method of well treatment includes: injecting a slurry comprising a degradable material, allowing the degradable material to form a plug in a perforation, a fracture, or a wellbore in a well penetrating a formation; performing a downhole operation; and allowing the degradable material to degrade after a selected time such that the plug disappears.

Abstract: A method of treating a subterranean formation penetrated by a wellbore includes preparing a treatment fluid with shear thinning, non-monotonic rheological properties, injecting the treatment fluid into the subterranean formation, and inducing shear rate softening phase transition in the treatment fluid. The non-monotonic rheology properties can be such that in the relationship between shear stress (?) versus strain rate ({dot over (?)}), where {dot over (?)}1<{dot over (?)}2<{dot over (?)}3<{dot over (?)}4, the shear stress values are ?1<?2?3??4, and ?3<?2 The method can heterogeneously deposit proppant or solid acid in a fracture. A system to fracture a subterranean formation includes the fracturing fluid, a wellbore to inject the fracturing fluid to propagate a fracture in the formation, and a rate controller to inject the fracturing fluid into the subterranean formation at a minimum volumetric rate to provide a shear stress at an inlet to the fracture that exceeds ?2.

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: A differential filter includes a swellable polymer that swells after contacting water such that permeability of the differential filter is reduced. A method of controlling water production in a well includes deploying a differential filter downhole; and performing a downhole operation, wherein the differential filter comprises a swellable polymer that swells after contacting water such that permeability of the differential filter is reduced.

Abstract: A method for well treatment by forming a temporary plug in a fracture, a perforation, a wellbore, or more than one of these locations, in a well penetrating a subterranean formation is provided, in which the method of well treatment includes: injecting a slurry comprising a degradable material, allowing the degradable material to form a plug in a perforation, a fracture, or a wellbore in a well penetrating a formation; performing a downhole operation; and allowing the degradable material to degrade after a selected time such that the plug disappears.

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: 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 is given for treating a subterranean formation penetrated by a wellbore with a viscosified fluid. The fluid contains a solid hydrolysable polyacid that upon dissolution and hydrolysis releases an acid that is a breaker for the viscosifying system. Suitable solid hydrolysable polyacids include polylactic acid and polyglycolic acid. The fluid also contains a pH control agent, present in an amount sufficient to neutralize any acid present in the solid hydrolysable polyacid before the injection and to neutralize any acid generated by the solid hydrolysable polyacid during the injection, so that the acid breaker is not available to break the fluid during the injection. In one embodiment the viscosifier is a viscoelastic surfactant fluid system and the solid hydrolysable polyacid is of a size selected to be a fluid loss additive, for example in fracturing or gravel packing.

Abstract: Methods are presented to induce a screenout during a subterranean formation fracturing or combined fracturing and gravel packing treatment having a viscoelastic surfactant-based carrier fluid by laying down a filter cake at least a portion of which is a base-soluble material, injecting proppant slurry, and causing hydrolysis and dissolution of the solid base-soluble material by adding base so that leak-off increases, the concentration of proppant in the fracture increases, and the proppant screens out. A method of gravel packing with a viscoelastic surfactant-based carrier fluid by laying down a filter cake at least a portion of which is a base-soluble material, injecting gravel, and causing hydrolysis and dissolution of the solid base-soluble material by adding base. Methods of slowing or accelerating the hydrolysis and dissolution are given, and addition of bridging-promoting materials is included.

Abstract: Methods are presented to induce a screenout during a subterranean formation fracturing or combined fracturing and gravel packing treatment having a viscoelastic surfactant-based carrier fluid by laying down a filter cake at least a portion of which is a base-soluble material, injecting proppant slurry, and causing hydrolysis and dissolution of the solid base-soluble material by adding base so that leak-off increases, the concentration of proppant in the fracture increases, and the proppant screens out. A method of gravel packing with a viscoelastic surfactant-based carrier fluid by laying down a filter cake at least a portion of which is a base-soluble material, injecting gravel, and causing hydrolysis and dissolution of the solid base-soluble material by adding base. Methods of slowing or accelerating the hydrolysis and dissolution are given, and addition of bridging-promoting materials is included.

Abstract: An improved method for transport of particulate matter in a wellbore fluid, and particularly the transport of particulate matter in subterranean wells, such as hydrocarbon wells, is disclosed, the method being characterized by utilization of specified fibers to aid in transport of the particulate matter. Additional embodiments include the removal of particulate matter (particles) and particle deposits, such as from drill cuttings, during the drilling of wells, and the removal of particulate matter deposits in cleanout operations.

Abstract: An improved method for cleanout of subterranean wells, such as hydrocarbon wells, is disclosed, the method being characterized by utilization of specified translocating fibers and/or platelets to aid in reduction of undesired fluids in the wellbore.

Abstract: Methods and apparatus are disclosed for fracturing subterranean formations using fracturing fluids that are hydrated from dry mix blends. One aspect of the invention comprises a dry blended particulate composition for hydraulic fracturing comprising a particulate hydratable polysaccharide, a particulate crosslinking agent, and a slowly releasing particulate base. The compositions employ controlled release methods of particle dissolution. The invention reveals a dry blended particulate composition capable of significantly improved high temperature stability. Further, methods of fracturing and apparatus for rapidly hydrating and pumping the fracturing fluid into subterranean formations are disclosed.