Experimental investigation of divalent ions and screening in smart water on calcite rock surface

Abstract

Massive demand for fossil fuel against limited available oil conventional reservoirs worldwide highlights that innovative enhanced oil recovery method. Nowadays, due to the accessibility of seawater and rivers, smart water and low salinity water injection have gained more attention. This paper addresses the mechanisms behind smart water injection and studies a real case from a carbonate oil reservoir. For this purpose, contact angle measurement was employed to screen and find the best smart water composition among different types of water. A core flooding experiment was used to evaluate the performance of the smart water injection in calcite rock. Two different scenarios were implemented in the core displacement experiment to examine the effect of divalent ions. Based on the experimental results, the main mechanism behind the smart water injection is the wettability alteration of the calcite rock surface. Also, as the most central divalent ions, an increase in calcium ions has been effective in increasing the water wetness of the rock surface, resulting in river water with double calcium ion content as the best smart water. [Received: November 8, 2021; Accepted: June 2, 2022]