Methods and compositions for delayed release of chemicals and particles

摘要

Agents, chemicals and particles may be controllably released at remote locations, such as pre-selected or predetermined portions of subterranean formations, by binding or associating or trapping them with an association of micelles formed by a viscoelastic surfactant (VES) in an aqueous base fluid to increase the viscosity of the fluid. An internal breaker within the association of micelles disturbs the association of micelles at some later, predictable or predetermined time thereby reducing the viscosity of the aqueous viscoelastic treating fluid and releasing the agent, chemical or particle at a predetermined or selected location.

主权项

1. A method for delayed treating of a subterranean formation with an agent comprising:
injecting an aqueous viscoelastic surfactant treating fluid through a wellbore and to the subterranean formation at a predetermined location within a reservoir, where the aqueous viscoelastic treating fluid comprises:
an aqueous base fluid;a viscoelastic surfactant (VES) gelling agent in an amount effective to form a VES gel that increases the viscosity of the aqueous viscoelastic surfactant treating fluid;at least one internal breaker within the VES gel, where the internal breaker is selected from the group consisting of mineral oils, fish oils, hydrogenated polyalphaolefin oils, transition metal ion sources, reducing agent sources, chelating agent sources, alkali metal sources, alkaline earth metal sources, saponified fatty acids, unsaturated or saturated fatty acids, and combinations thereof; andan agent within the VES gel, breaking the VES gel with the internal breaker thereby reducing the viscosity of the aqueous viscoelastic surfactant treating fluid; and thereby releasing the agent from the VES gel into the predetermined location in the subterranean formation at a predetermined time after the injecting.