An experimental study of alcohol injection to mitigate water blockage in commingled layered reservoirs

Abstract

This study explores the effectiveness of alcohol injection as a stimulation treatment to mitigate water blockage in the vicinity of the wellbore. Over the years, water blockage has emerged as a recurring challenge within the oil and gas industry, leading to diminished well productivity. In a commingled reservoir with multiple layers, when a producing well is shut-in for well intervention or workover, water may encroach from water zones into the oil-bearing formations through the wellbore due to pressure differences between the layers. Water encroachment can have a significant impact on the production of a well. It can reduce the oil production rate, increase the water cut, and shorten the well's lifespan. Therefore, it is essential to take steps to mitigate the water encroachment effect in commingled reservoirs. This study explores the use of alcohol injection to reduce transition time and remediate formation damage in commingled oil reservoirs. Limited studies have shown that alcohol has the potential to enhance fluid relative Permeability in gas condensate reservoirs and reduce condensate banking near the wellbore. However, this approach has not yet been tested in commingled oil reservoirs. A series of core flooding tests were conducted using Berea sandstone cores and a Texan light crude oil sample. The core flood setup was designed to represent the water blockage condition in the formation. Two different alcohols were tested: isopropyl alcohol (IPA) and Methanol. Experimental results showed that mutual solvents significantly reduce water blockage and shorten the transition period. However, asphaltene precipitation may become a problem with increasing the molecular weight of injected alcohol.