A Case Study to Evaluate and Explore the Upside Potential of a Mature Field (Ras El Ush) Located in One of the Best Exposed Continental Rift of the Late Cenozoic Gulf of Suez Basin

Abstract

Abstract The Ras El Ush field has been producing since 1996 and has a recovery factor of more than twenty five percent. The field - one of the best-exposed continental rifts of the Gulf of Suez Basin - is structurally complex. The average reservoir formation dips are around 20–40 degrees and bounded by high angle faults (~55 degrees) and the reservoir is divided into several blocks due to many tectonic episodes. Due to this structural complexity, no seismic events can be seen on either the bounded faults or through major reflectors except a few cross faults. This paper will demonstrate how an integrated reservoir modeling and simulation workflow filled this information gap, calculated reserves potential, and determined the investment potential of the field. The paper will illustrate how a static model was built, uncertainty quantified using well data, and how a complex structural model was developed based on geological concepts, well data, outcrops and field knowledge that showed significant improvement in Gross Rock Volume (GRV) estimations. Instead of applying constant shift, a variable uncertainty was applied to quantify the GRV and P10/P50/P90 values. The paper will illustrate how structural model realizations were generated through the moving of the boundary faults and horizons in order to evaluate the GRV uncertainties and quantify the P10/P50/P90 GRV values of Stock Tank Oil in Place (STOIP). The Matulla reservoir units were also subdivided into four units to capture the reservoir's heterogeneities. Reservoir fluid characterization and Equation of State (EOS) modeling was also carried out to match the observed PVT experiments. Finally, reserves estimation of the field were also verified using material balance, decline curve analysis and dynamic simulation. The simulation model was initialized through the equilibration facility by calculating the initial conditions on the basis of hydrostatic equilibrium using capillary pressure, observed initial hydrocarbon contacts, and reservoir pressures that showed the acceptable history match. Together, the integrated reservoir modeling, simulation and history matching workflow provided a close to realistic value of the reserves and parameter dependencies allowing the mitigation of investment risk. Following simulation, it was concluded that the Ras El Ush field had upside potential and that more wells would be drilled.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015