Fines migration and formation damage; Influence of pH and ion exchange

Abstract

This paper elucidates the influence of pH and ion exchange on formation damage caused by fines migration. The experimental results affect waterflooding, design of drilling muds, and alkaline flooding. In-situ release of naturally existing fines (generally clays) results form change sin colloidal conditions of the permeating fluid. Such processes can cause extensive formation damage in sandstones, thereby reducing oil production. The authors' recent studies clearly indicate that the release process is started by a combination of high pH, leading to drastic permeability reductions. These results therefore provide new insight into the phenomenon of formation damage caused by water sensitivity or injection of incompatible brines. The authors also describe a unified approach to understanding these results and the findings of previous investigators.