Improved Oil Recovery for Fractured Granite Basement Reservoirs: Historical Lessons, Successful Application, and Possibility for Improvement

Abstract

Abstract Discovery and development of naturally fractured reservoir has increased dramatically during past 15 years because more fractured reservoirs are being developed as production from conventional reservoirs is declining. Many oil reservoirs in the world are naturally fractured, but relatively little research has been done on the use of advanced oil recovery methods. In addition, very little success has been achieved in increasing the oil production from these complex reservoirs. Some laboratory experiments have been done to investigate the use of IOR methods for fractured reservoir; however, the results of these studies hard to interpret and to apply to field scale predictions. Thus, it is urgent and necessary to collect the experiences from previous successful researches to reduce the risk level. This study addresses methods and recent advances to enhance oil production in fractured granite basement reservoir of White Tiger field. It is the biggest fractured reservoir up to now on the continental shelf of Vietnam. But, the geological characterization of this reservoir is extremely complex with high uncertainty and challenge in production strategies. Therefore, a numerous of studies were conducted to develop the favorable IOR techniques including advanced emulsion acidizing stimulation, microbial enhanced oil recovery methods, artificial water buffer, directional drilling application, and gel treatment for basement reservoir. These special approaches were achieved many precious successes in increase the recovery factor from 29% to 44.33% and would be significantly extended the life of reservoir. Regarding to the unique characterization of White Tiger field and lack of experiences of producing in fractured basement reservoir, the lessons learned and experiences gained from past 20 historical years are a worthy case study for both current and future development of NFR in the world.