Encapsulated chemicals for use in controlled time release applications and methods
First Claim
1. An improved method of removing drilling fluid filter cake in a well bore penetrating a subterranean producing formation comprising the steps of:
- (a) preparing a cleaning composition comprising water and a controlled time release encapsulated particulate solid acid or an acid forming chemical, said particulate solid acid or acid forming chemical having a first coating of a hydrophobic film forming material or a sparingly soluble material which provides a dry shield on said acid or chemical and provides a delay in the release of said acid or chemical for a time period of less than about 2 hours, and a second coating of a porous cross-linked hydrophilic polymer which prevents the substantial dissolution of the resulting encapsulated acid or chemical for a selected period of time;
(b) placing said cleaning composition in said well bore adjacent to said subterranean formation to be cleaned; and
(c) allowing said cleaning composition to react with and remove said filter cake and the like.
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Accused Products
Abstract
Encapsulated water soluble chemicals for use in controlled time release applications, methods of encapsulating the chemicals and methods of using the encapsulated chemicals are provided. The methods of encapsulating the chemicals are basically comprised of forming a first coating of a dry hydrophobic film forming material or a sparingly soluble material which provides a dry shield on the chemical and then forming a second coating of a porous cross-linked hydrophilic polymer on the first coating which prevents the substantial dissolution of the resulting encapsulated chemical for a selected period of time.
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Citations
24 Claims
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1. An improved method of removing drilling fluid filter cake in a well bore penetrating a subterranean producing formation comprising the steps of:
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(a) preparing a cleaning composition comprising water and a controlled time release encapsulated particulate solid acid or an acid forming chemical, said particulate solid acid or acid forming chemical having a first coating of a hydrophobic film forming material or a sparingly soluble material which provides a dry shield on said acid or chemical and provides a delay in the release of said acid or chemical for a time period of less than about 2 hours, and a second coating of a porous cross-linked hydrophilic polymer which prevents the substantial dissolution of the resulting encapsulated acid or chemical for a selected period of time;
(b) placing said cleaning composition in said well bore adjacent to said subterranean formation to be cleaned; and
(c) allowing said cleaning composition to react with and remove said filter cake and the like. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification