Schlumberger Technology Corporation

Belgin Baser

Carlos Abad

Yiyan Chen

Philip F Sullivan

Lijun Lin

Jesse Lee

Curtis L Boney

Jorge E Lopez De Cardenas

Eric Clum

Leiming Li

Erik B Nelson

Mehmet Parlar

Gregory Kubala

Jason Swaren

Sascha Trummer

Christopher N Fredd

Dean M Willberg

Golchehreh Salamat

Marina Nikolaevna Bulova

Timothy L Pope

Ann M W Hoefer

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.

Oxidative internal breaker system with breaking activators for viscoelastic surfactant fluids

A method for placing ball sealers within a well formed within a subterranean formation for sealing holes in a casing of the well is carried out by performing at least one of two operations. The first operation involves providing a tag with at least one ball sealer or a carrier fluid containing the at least one ball sealer to facilitate monitoring of the location of the ball sealer. A tag monitoring device is provided within the well for monitoring the location of the tag. The ball sealer and carrier fluid with the tag are introduced downhole into the well. Information from the monitor device regarding the location of the tag is communicated to a remote monitoring location to the thereby provide an indication of the location of the tag within the well to a surface location. In the second operation a container is provided within the well at a known location downhole within the well. The container contains at least one ball sealer. The ball sealer or sealers are released from the container within the well at the known location in response to an instruction initiated from a surface location.

Method of placing ball sealers for fluid diversion

A multilayered ball sealer having a deformable layer. The multilayered ball sealer has an outer or intermediate layer that is deformable under pressure. In the former, the deformable layer may be water-soluble or hydrolysable. In the latter, the outer layer is a sheath that contains the deformable layer and adapts to its shape. A multilayered ball sealer may be used as a diversion agent by being suspended in a fluid injected into a wellbore and applying pressure to deform the shape of the intermediate layer such that the multilayered ball sealer adapts to the shape of a perforation opening on which the multilayered ball sealer has seated.

Multilayered ball sealer and method of use thereof

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.

Oxidative internal breaker for viscoelastic surfactant fluids

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.

Internal breaker for oilfield treatments

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.

Internal breaker for oilfield fluids

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.

Well treatment with dissolvable polymer

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Houston, TX, United States of America

Belgin Baser