Gelling agent for water shut-off in oil and gas wells

摘要

The gelling agent for water shut-off in oil and gas wells is a composition that forms a gel to reduce or eliminate the flow of water in a gas or oil well. The composition is formed by mixing polyvinyl alcohol, a polyvinyl alcohol copolymer, or mixtures thereof with an amino-aldehyde oligomer, such as urea formaldehyde or melamine formaldehyde, with or without a cross-linker. The polymer composition can be used to minimize or completely shut off excess water production with insignificant reduction in hydrocarbon productivity.

主权项

1. A method for retarding water flow in a hydrocarbon-producing subterranean formation while permitting hydrocarbon flow through the formation, comprising the steps of:
(a) introducing an effective amount of a gel-forming composition into a zone of the subterranean formation having permeability to water, the gel-forming composition being operable when gelled in the zone for retarding the flow of water therein while permitting hydrocarbon flow, the gel-forming composition being an aqueous mixture of polymers, the polymers including: (1) a water soluble polymer selected from the group consisting of polyvinyl alcohol, a copolymer of polyvinyl alcohol, and mixtures thereof; and (2) an amino aldehyde oligomer, the amino aldehyde oligomer being between 50% and 90% of the combined weight of the water soluble polymer and the amino aldehyde oligomer, the concentration of the polymers in the gel-forming composition being between about 6.25% g/cc and about 48% g/cc; and (3) at least one gelation retarder selected from the group consisting of lignosulfonates and sulfonated naphthalene formaldehyde; and (b) allowing the gel-forming composition to form a gel in the zone of the subterranean formation, thereby retarding the flow of water therein while permitting hydrocarbon flow.