Well treatment methods and fluids

摘要

A method includes forming a well treatment fluid by combining an aqueous fluid, a viscosifying agent, a crosslinker, and a rheology modifier containing an aldehyde. The viscosifying agent is crosslinked, increasing viscosity of the fluid. The method includes treating a well with the fluid exhibiting the increased viscosity, chemically changing the aldehyde after the crosslinking and thereby forming an acid, and decreasing viscosity of the crosslinked fluid as a result of forming the acid. The aldehyde may be glyoxal which forms oxalic acid, breaking a crosslink. A well treatment fluid is formulated with ingredients including an aqueous fluid and a viscosifying agent and a crosslinker configured to crosslink the viscosifying agent. The fluid includes a rheology modifier containing an aldehyde. The fluid may lack an aldehyde crosslinking delay additive.

主权项

1. A well treatment method comprising:
forming a well treatment fluid by combining ingredients including an aqueous fluid, a viscosifying agent, a crosslinker, and a rheology modifier containing glyoxal; crosslinking the viscosifying agent in the aqueous fluid using the crosslinker, the glyoxal not delaying the crosslinking and the crosslinking increasing viscosity of the well treatment fluid to a first viscosity; treating a well with the well treatment fluid exhibiting the first viscosity; chemically changing the glyoxal after the crosslinking and thereby forming oxalic acid, the glyoxal not being substantially chemically changed before the crosslinking; and after treating the well, decreasing viscosity of the crosslinked well treatment fluid to a second viscosity less than the first viscosity as a result of forming the oxalic acid.