Method of reducing water influx into gas wells
View Patent ↗A method of reducing water influx into a wellbore, wherein the wellbore is in fluid communication with a subterranean formation such as a gas producing formation or gas reservoir. The method particularly places a gelant in a desired position down the wellbore and into the formation in order to thereby reduce the influx of water and enhance the resulting gas production. The method includes the steps of first introducing a gelant into the wellbore and second introducing a temporarily stable foam into the wellbore in order to overdisplace the gelant from the wellbore and into the formation.
1. A method of reducing water influx into a wellbore, comprising the following steps:
(a) first introducing a gelant into the wellbore, wherein the wellbore is in fluid communication with a subterranean formation, wherein the gelant is comprised of a polymer and a cross-linker;
(b) subsequent to first introducing the gelant, introducing a temporarily stable foam into the wellbore in order to overdisplace the gelant from the wellbore and into the formation; and
(c) providing a set-up period to permit the gelant to set to form a gel block in the formation and to permit the temporarily stable foam to break down to permit the passage of gas through the foam into the wellbore.
2. The method as claimed in claim 1 wherein the polymer is comprised of a polyacrylamide.
3. The method as claimed in claim 2 wherein the cross-linker is comprised of chromium ions.
4. The method as claimed in claim 3 wherein a ratio by weight of the polyacrylamide to the chromium ions in the gelant is no greater than about 80 to 1.
5. The method as claimed in claim 3 wherein the polymer is comprised of a polyacrylamide having a molecular weight of greater than about 1,000,000 and wherein a concentration of the polyacrylamide in the gelant is no greater than about 2 percent by weight of the gelant.
6. The method as claimed in claim 5 wherein the formation is a fractured formation.
7. The method as claimed in claim 6 wherein the concentration of the polyacrylamide in the gelant is no greater than about 1 percent by weight of the gelant.
8. The method as claimed in claim 3 wherein the formation has a permeability and wherein the permeability of the formation is greater than or equal to about 1000 mD.
9. The method as claimed in claim 8 wherein the polymer is comprised of a polyacrylamide having a molecular weight of greater than about 1,000,000 and wherein a concentration of the polyacrylamide in the gelant is between about 0.2 and 1 percent by weight of the gelant.
10. The method as claimed in claim 3 wherein the formation has a permeability and wherein the permeability of the formation is less than about 1000 mD.
11. The method as claimed in claim 10 wherein the polymer is comprised of a polyacrylamide having a molecular weight of less than or equal to about 1,000,000 and wherein a concentration of the polyacrylamide in the gelant is at least about 1 percent by weight of the gelant.
12. The method as claimed in claim 1 wherein the foam is comprised of water and a surfactant.
13. The method as claimed in claim 12 wherein the surfactant is comprised of an olefin sulfonate.
14. The method as claimed in claim 13 wherein the surfactant is comprised of alpha olefin sulfonate.
15. The method as claimed in claim 14 wherein a concentration of the surfactant in the foam is no greater than about 0.1 percent by weight of the foam.
16. The method as claimed in claim 15 wherein the concentration of the surfactant in the foam is no greater than about 0.05 percent by weight of the foam.
17. The method as claimed in claim 1 wherein the gelant has a gelant viscosity in situ, wherein the foam has a foam viscosity in situ, and wherein the gelant viscosity in situ and the foam viscosity in situ are approximately equal.
18. The method as claimed in claim 1 wherein the gelant has a gelant viscosity in situ, wherein the foam has a foam viscosity in situ, and wherein the gelant viscosity in situ is less than or about equal to the foam viscosity in situ.