Self-destructive barite filter cake in water-based and oil-based drilling fluids

Abstract

The complete removal of filter cake containing barium sulfate is a challenging and difficult task because of the involvement of various issues such as incompatibility and insolubility. Conventional filter cake removal techniques include the use of chelating agents, which are ineffective in completely removing the barite filter cakes. Barite is completely insoluble in water as well as in various acids, such as acetic acid, lactic acid, hydrochloric acid, and formic acid. In this study, a novel method is introduced to remove the barium sulfate filter cake by introducing a new formulation of both oil-based and water-based drilling fluids. The new formulation can prevent fluid loss as well as self-destruct the barium sulfate filter cake, which can be formed with oil-based and water-based drilling fluids. The new formulation is comprised of encapsulated thermochemical fluids in addition to the conventional drilling fluids additives. These thermochemical fluids can cause a strong exothermic reaction that can significantly increase the surrounding temperature and pressure. The generated heat and pressure can dissolve or dislodge the filter cake formed with drilling fluid. The laboratory experimental results showed that the new formulation could completely remove the filter cake in a single stage within 48 h. In addition to that, the new formulation resulted in the creation of micro-fractures, which can enhance the flowback and help in well cleanup process after drilling. The new formulation can be used as a promising formula to remove the filter cake before cementing operation.