Review of Enhanced Oil Recovery Decision Making in Complex Carbonate Reservoirs: Fluid Flow and Geomechanics Mechanisms

As a result of reduction trend in exploration of super-giant carbonate fields and depletion of the proven mature fields categorized as easy oil, development of tight, deep carbonates with more complexities in reservoir rock and fluid behavior have become of interest for exploration and development companies in recent years. New challenges have arisen in development of complex carbonates due to fracture network distribution uncertainty, lateral and vertical fluid behavior heterogeneities, unstable asphaltene content, high H2S and CO2 contents and high salinity formation brine. The complexity elements and problems for downhole sampling have made the full understanding of the reservoir behavior and consequently availability of data for further routine analysis and utilization of simulation model as the main way of data integration limited. Therefore, there is an emerging need to better understand the challenges surrounding production and enhanced oil recovery strategies in these reservoirs for an improved oil recovery decision making system. In this paper, the challenges in production, stimulation and enhanced oil recovery strategies in newly-developed complex carbonates are addressed and analyzed based on the changes to the chemical and mechanical environment. An integrated decision-making workflow based on coupled hydro-mechanical mechanisms in water-based EOR methods is discussed.