Surface Charge Investigation of Reservoir Rock Minerals

The reservoir rock is made up of different minerals and its surface chemistry is influenced by the reservoir environment. Well operations implemented during the life of a field induce changes in the reservoir environment (pH) that affect the minerals, resulting in a change of their surface chemistry. These changes result in wettability alterations, which have a significant effect on the overall production. Thus, this research provides insight into the behavior of calcite, feldspar, barite, dolomite, quartz, and sand in varying pH environments to ascertain the effect of pH change on mineral surface charge. This study employed ζ-potential measurements as a measure of the wettability alteration. The findings reveal that these rock minerals have their charge development controlled by mineral dissolution, ionic specie adsorption, and double-layer compression. Furthermore, the rock contacting mineral is critical in the wettability alteration, and an understanding of the effect of well operations on rock surface chemistry is critical.