Methods for increasing wellbore strength
AssigneeBoard of Regents, The University of Texas System
InventorsEric Van Oort, Besmir B. Hoxha, Ali Karimi Vajargah, Robert O. Williams, III, Hugh Smyth, Silvia Ferrati
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Abstract
Disclosed herein are compositions and methods for reducing fluid loss in a well bore, methods for wellbore strengthening and increasing the integrity of the borehole of an oil or gas well. Also disclosed are methods for artificially increasing the temperature of a subsurface formation in the wellbore to increase the apparent wellbore strength. The mechanism for accomplishing this revolves around increasing fracture propagation pressure by actively manipulating thermal wellbore stresses.
Claims20
A method for heating fluid in a wellbore, comprising:
- a) contacting a carrier fluid with a composition, wherein the composition comprises:
- a plurality of encapsulated payloads, each of the encapsulated payloads consists of a payload surrounded by a shell, wherein the payload comprises:
- i) a hygroscopic salt present in an amount of 15-99% by weight of the payload;
- and
- ii) a binder present in an amount from 1% to 20% by weight of the payload;
- and
- the shell comprises a polymer layer comprising polymers selected from the group consisting of water-insoluble polymers, water-swellable polymers, and combinations thereof, wherein the shell does not include a water-soluble polymer;
- b) delivering the carrier fluid and the composition to the wellbore;
- and
- c) releasing the hygroscopic salt from the encapsulated payloads in the wellbore, thereby causing an exothermic event that heats the fluid in the wellbore.
A composition comprising:
- a plurality of encapsulated payloads, each of the encapsulated payloads consists of a payload surrounded by a shell, wherein the payload comprises:
- i) a hygroscopic salt in an amount of 15-99% by weight of the payload;
- and
- ii) a binder present in an amount from 1% to 20% by weight of the payload;
- and the shell comprises a layer of microspheres surrounding the payload, and a polymer layer surrounding the layer of microspheres
- wherein the polymer layer comprises polymers selected from the group consisting of water-insoluble polymers, water-swellable polymers, and combinations thereof;
- wherein the shell does not include a water-soluble polymer;
- and
- wherein the shell is configured to controllably release the hygroscopic salt from at least one of the plurality of encapsulated payloads at predetermined conditions, and thereby to cause an exothermic event, in a wellbore.
A composition comprising:
- a plurality of encapsulated payloads, each of the encapsulated payloads consists of a payload surrounded by a shell, wherein the payload comprises:
- a hygroscopic salt present in an amount of 15-99% by weight of the payload;
- and
- a binder present in an amount from 1% to 50% by weight of the payload
- the shell comprises a polymer layer, wherein the polymer layer comprises polymers selected from the group consisting of water-insoluble polymers, water-swellable polymers, and combinations thereof;
- and
- wherein the shell does not include a water-soluble polymer;
- wherein two or more of the encapsulated payloads are agglomerated within a polymer matrix;
- and
- wherein the shell is configured to controllably release the hygroscopic salt from at least one of the plurality of encapsulated payloads at predetermined conditions, and thereby to cause an exothermic event in a wellbore.
Dependencies are inferred from the claim text.