Wettability Alteration of Berea Sandstone for Gas Condensate Applications.

Abstract

Gas condensate reservoirs can suffer significant decreases in production due to the buildup of liquid in the vicinity of the wellbore, which occurs when the bottom-hole flowing pressure drops below the dew point pressure. Consequently, the generated liquid hydrocarbons can hinder the movement of the produced gas by adhering to the surfaces, thereby creating a condensate bank. One potential method for mitigating the issue of condensate banking involves the injection of chemical treatment and the alteration of wettability from a liquid-wet state to an intermediate gas-wet state. This study conducted an experimental investigation of the impact of fluorochemical treatment on altering the wettability from liquid-wetting to intermediate gas-wetting. The wettability of the Berea sandstone was analyzed before and after chemical treatment over a temperature range of 25-83 °C. The outcrop core samples of Berea sandstone used in this investigation exhibited an average porosity and permeability of 20% and 100 mD, respectively. The experimental results indicate that the application of chemical treatment has the potential to alter the wettability of Berea sandstone, transitioning it from a state of liquid-wetting to gas-wetting at standard temperatures. The chemical treatment alters the wettability from liquid-wet to intermediate gas-wet at higher temperatures. Furthermore, the alteration of wettability substantially improves the mobility of the oil phase and decreases the residual saturation of the oil, thereby aiding the reduction of liquid accumulation around the wellbore. According to this research, altering the wettability of the rock surrounding the wellbore in gas condensate reservoirs from a state of strong liquid-wet to gas-wet has the potential to enhance the deliverability of gas wells and improve injectivity in the field.