Selective gel system for permeability profile control
AssigneeMobil Oil Corporation
InventorPaul Shu
Life of this patent
Estimating the term…
Abstract
An aqueous gel composition is formed from xanthan gum crosslinked with ions of a transitional metal, resorcinol, and formaldehyde. The gel which initially forms is injected into a formation where it selectively enters pores in a more permeable zone. Once in the more permeable zone, the gel reheals and forms a shear and thermally stable gel. This gel can be used in high temperature formations in addition to those formations having a pH of from about 3.0 to about 10. After the shear and thermally stable gel has formed, a steam-flooding, water-flooding, or a carbon dioxide oil recovery process is commenced in a zone of lesser permeability.
Claims18
A process for closing pores in a more permeable zone of a formation comprising:
- (a) placing into an aqueous solution a first composition sufficient to form ex-situ a size selective, shear thinning first gel which comprises
- (i) a xanthan biopolymer, and
- (ii) a transitional metal ion;
- (b) placing into said aqueous solution a second composition sufficient to form thermally a second in-situ gel which is substantially more resistant to formation conditions than said first gel which composition comprises
- (i) an aldehyde, and
- (ii) a phenolic compound;
- (c) allowing said aqueous solution sufficient time to form the ex-situ gel;
- and
- (d) injecting said aqueous solution containing said gel into said permeable zone where it reheals, is heated by the formation and thereafter forms a solid gel substantially more resistant to formation conditions than said first gel.
A process for closing pores in a more permeable zone of a formation comprising:
- (a) placing into an aqueous solution a first composition sufficient to form ex-situ a size selective, shear thinning first gel which comprises
- (i) about 0.1 to about 1.0 wt. % of a xanthan biopolymer, and
- (ii) about 20 to about 1,000 ppm of a transitional metal ion and mixtures of transitional metal ions;
- (b) placing into said aqueous solution a second composition sufficient to form thermally a second in-situ gel which is substantially more resistant to formation conditions than said first gel which composition comprises
- (i) about 0.25 to about 5 wt. % of resorcinol, and
- (ii) about 0.5 to about 3 wt. % of formaldehyde;
- (c) allowing said aqueous solution sufficient time to form the ex-situ gel;
- and
- (d) injecting said aqueous solution containing said gel into said permeable zone where it reheals, is heated by the formation and thereafter forms a solid gel substantially more resistant to formation conditions than said first gel.
Dependencies are inferred from the claim text.