Abstract:
The world is on the verge of energy crisis due to rising demand for fossil fuel to meet domestic and industrial energy requirements. In order to meet the rising fossil fuel need, the development of a framework for enhanced hydrocarbons recovery from mature reservoirs should be given a high priority given the fact that 70% of world oil production comes from mature reservoirs. The objective of this research project is to develop a framework for enhanced hydrocarbons recovery from mature reservoirs using Big Escambia Creek (BEC) field as a case study. This developed framework is hinged on accurate characterization of reservoir rock and fluid properties, successful modeling of variation of average reservoir pressures with time, and presentation of existing well models and how to appropriately represent them in numerical simulators to ensure performance of successful reservoir simulation studies. In order to ensure successful development of a framework, the Smackover reservoir portion of BEC field was comprehensively characterized to delineate the porosity and permeability profiles of the field using laboratory measured porosity and permeability data, as well as well log porosity data. In addition, the average reservoir pressure, which is required to estimate initial hydrocarbon in place, estimate hydrocarbon reserves, and monitor reservoir performance, was modeled with a decaying exponential function using static bottom-hole pressures available for some wells on the field. Furthermore, accurate modeling of reservoir fluid using available commercial fluid simulators, such as PVTi, was impossible due to high concentration of acid gas. Therefore, least square optimization technique was used to accurately model the fluid. The reservoir fluid PVT properties obtained through this technique were used successfully to estimate initial hydrocarbon in place and determine aquifer influence on BEC field using material balance calculations. The original hydrocarbon in place of 1.502 Tcf of gas obtained was in perfect agreement with earlier estimates made using pressure decline data and volumetric calculations. On the basis of this developed framework, simulation studies for enhanced hydrocarbons recovery could be performed on BEC field and other fields with similar rock and fluid properties in USA and around the world.
