Hydrolysis-Promoted Polymerization of Furfuryl Alcohol: Selective Method for Mitigating Excess Water Production in Oil Wells

Abstract

Abstract Water production during hydrocarbon extraction is a major problem for the upstream oil and gas industry. The challenge posed for operators is the increase in operational costs pertaining to separation, treatment, and disposal processes, amongst others. A wide assortment of scenarios can lead to unwanted water production from wells in hydrocarbon producing zones such as casing leaks, cusping, water breakthrough due to the presence of natural fractures or high permeability streaks, etc. Methods of treatment are not a one-size-fits-all approach but range from being simple to more complex. To best mitigate the problem, particularly in the long-term, it is necessary to perform a thorough evaluation to understand the location and cause of the water production. Key existing solutions use mechanical devices, chemical methods, or combinations thereof to form a semi-to-impermeable barrier to prevent the flow of water from reaching the wellbore. While potentially very effective, the longevity of such methods is hindered by lack of efficiency, selectivity, stability, high cost and placement risks in relation to the completion type. Here, we report on the development, formulation, and performance evaluation of a robust thermoset resin system that is inherently selective for blocking water -bearing zones in oil producing formations. The strategy behind this approach is based on acid-catalyzed polymerization of furfuryl alcohol. Specifically, use of judiciously selected acid-generating precursors, namely ester-containing compounds that are hydrophobic in nature. Under suitable reaction conditions, hydrolysis takes place at the interfacial boundary thereby releasing acid and directing blockage specifically to the water zone via resin formation. The resin system has been formulated for application in carbonate or sandstone reservoirs with temperatures up to 150 ˚C and set times up to 48 h. In this study, an overview of our down-selection process for ester selection guided by static bottle test results and regained permeability data obtained under reservoir conditions using a coreflood apparatus will be discussed. This chemical method for mitigating excess water production in oil wells is configured to selectively plug the water producing zones without affecting the oil producing zone. Instead, it is proposed that suitable chemical placement can be achieved by bullheading the treatment into the formation thereby reducing operational complexity and cost.