Abqaiq field is one of the largest and most mature oil fields in Saudi Arabia. The two producing reservoirs, Arab-D and Hanifa, are both fractured and are separated by the very thick non-reservoir Jubaila formation. The Arab-D and Hanifa are in direct hydraulic communication through faults and fractures. New geologic and simulation models were built for the three formations of interest using Dual Porosity/Dual Permeability (DPDP) formulation and enabling optimization of the field production/injection and acceleration of recovery of this complex system.
Detailed fracture characterization was conducted on cores and borehole images. Fracture intensity formulae were developed based on geologic drivers such as structural curvature, porosity, lithology, bed thickness and stylolite density. The generated fracture network was upscaled using a single-phase method to obtain fracture permeability. The final simulation model was developed by up-layering of the 14 million cells geological matrix model to 2.5 million cells. Simulation of multi-million cell models with DPDP formulation is now both economical and practical with the utilization of Massive Parallel Processing (MPP) technology.
A workflow was developed to model the two fractured reservoirs with inter-reservoir communication through fractured non-reservoir formation using DPDP options. Equivalent Single Porosity/Single Permeability (SPSP) and a hybrid SPSP/DPDP models were also constructed to speed up the history match process and to gain insight into the reservoir fluid flow. Significant gain of turn-around time was established through the utilization of MPP and SPSP model. The SPSP model runs seven times faster than the DPDP model under MPP. The DPDP model improves history match quality in Hanifa reservoir and predicts well performances more accurately in this fracture dominated system. Results of these three multi-million cell models have contributed to the deeper understanding of recovery mechanism leading to improved efficient optimization of production and injection strategies for this complex field.
