Study on an Anti-temperature Autogentic Acid System with Controllable Acid Concentration and Its Application

The deep high-temperature carbonate gas reservoirs represented by the Gaomo block in Central Sichuan and the Penglai Gasfield have become an important support for the Southwest Oil & Gasfield Company to increase reserves and production on a large scale. However, there are many technical problems in the acidizing transformation of high-temperature reservoirs, such as fast acid rock reaction speed, preferential acid etching distance, strong corrosivity and so on. In this paper, the mechanism of autogenous acid generation and its reaction with acid rock are revealed, the kinetic equations and thermodynamic equations are constructed, and the technical countermeasures for the research of high temperature autogenous acid resistance are put forward. A series of autogenous acid systems with controllable concentration of autogenous hydrochloric acid and autogenous organic acid have been developed respectively. The controllable acid concentration is 6−12% and the temperature resistance reaches 180 ℃. The generated acid systems have the performance advantages of long acid generation time and high effective corrosion rate, which can significantly slow down the acid rock reaction rate, improve the acid etching distance, and achieve the purpose of deep penetration. A series of authigenic acids and their supporting technologies have been successfully popularized and applied in deep carbonate reservoirs in Sichuan, serving more than 100 wells and using more than 10000 m3 of acid, effectively solving the technical problems existing in the acidizing transformation of high-temperature reservoirs, and achieving remarkable economic benefits.