Self-breaking viscous aqueous solutions and the use thereof in fracturing subterranean formations
AssigneeThe Dow Chemical Company
InventorsDustin L. Free, Karl L. Krumel, Travis C. Snyder
Life of this patent
Estimating the term…
Abstract
Viscous aqueous solutions are prepared which maintain a certain viscosity range over a predetermined period of time (i.e., induction period) and which thereafter break, i.e., decrease in viscosity over a very short period of time. The viscous aqueous solution comprises a polysaccharide having an ability to thicken water and dispersed or dissolved in the aqueous solution an effective quantity of an organic ester which, at a temperature at which it is desired to break the viscous solution, hydrolyzes over a delayed period of time to form an acid which degrades the polysaccharide, thus causing a splitting of the polysaccharide chain and a decrease in the viscosity of the solution.
Claims18
A viscous aqueous well treating composition which has a certain viscosity for a predetermined period of time at a certain temperature and which subsequently breaks to form a lower viscosity fluid within a short period of time, which comprises:
- a viscous aqueous solution containing a sufficient quantity of a polysaccharide-thickening agent, containing acetal linkages and which, in an aqueous solution is degraded by an acid to provide a solution having a desired viscosity at the temperature of use and an effective quantity of a C.sub.1 - C.sub.12 organic ester of a carboxylic acid, which hydrolyzes in said aqueous solution at said temperature of use to produce an acid which degrades the polysaccharide and causes the viscosity of the aqueous composition to be lowered to a desired lower level.
Dependencies are inferred from the claim text.