Preventing flow through subterranean zones
First Claim
1. An improved method of preventing the flow of water or gas or both through a subterranean zone penetrated by a well bore comprising the steps of:
- (a) preparing a polymeric sealing composition comprised of water, a biodegradable and non-toxic cross-linking agent comprised of chitosan and a selected water soluble polymer which reacts with said cross-linking agent and forms a sealing gel which is stable for a desired period of time at the temperature of said zone and has a pumping time before gelation in the presence of said cross-linking agent whereby said composition can be pumped to the depth of said zone and placed therein;
(b) pumping said sealing composition into said zone by way of said well bore; and
(c) allowing said sealing composition to form a cross-linked gel in said zone.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention provides methods of preventing the flow of water or gas or both through a subterranean zone having a high temperature and a depth such that a long pumping time is required to place a sealing composition therein. The methods basically comprise the steps of preparing a polymeric sealing composition comprised of water, a cross-linking agent and a selected water-soluble polymer which reacts with the cross-linking agent and forms a sealing gel which is stable for a desired period of time at the temperature of the zone and has a pumping time before gelation in the presence of the cross-linking agent whereby the composition can be pumped to the depth of the zone and placed therein. Thereafter, the sealing composition is pumped into the zone and allowed to form a sealing gel therein.
-
Citations
16 Claims
-
1. An improved method of preventing the flow of water or gas or both through a subterranean zone penetrated by a well bore comprising the steps of:
-
(a) preparing a polymeric sealing composition comprised of water, a biodegradable and non-toxic cross-linking agent comprised of chitosan and a selected water soluble polymer which reacts with said cross-linking agent and forms a sealing gel which is stable for a desired period of time at the temperature of said zone and has a pumping time before gelation in the presence of said cross-linking agent whereby said composition can be pumped to the depth of said zone and placed therein;
(b) pumping said sealing composition into said zone by way of said well bore; and
(c) allowing said sealing composition to form a cross-linked gel in said zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method of preventing the flow of water or gas or both through a subterranean zone comprising the steps of:
-
(a) preparing a polymeric sealing composition comprised of water, a biodegradable and non-toxic cross-linking agent comprised of chitosan and a selected water soluble polymer which reacts with said cross-linking agent and forms a sealing gel which is stable for a desired period of time at the temperature of said zone and has a pumping time before gelation in the presence of said cross-linking agent whereby said composition can be pumped to the depth of said zone and placed therein, said water soluble polymer being selected from the group consisting of polyacrylamide, AMPS®
/acrylamide copolymers, sulfonated styrene/maleic anhydride copolymers, vinylpyrrolidone/AMPS®
/acrylamide terpolymers, AMPS®
/N-N-dimethylacrylamide/acrylamide terpolymers and mixtures thereof;
(b) pumping said sealing composition into said zone by way of said well bore; and
(c) allowing said sealing composition to form a cross-linked gel in said zone. - View Dependent Claims (14, 15, 16)
-
Specification