Black Oil Delumping: Running Black Oil Reservoir Simulations and Getting Compositional Wellstreams in the North Kuwait Jurassic Complex

Abstract

Abstract The North Kuwait Jurassic Complex (NKJC) consists of five fields, each with three identified reservoirs within the naturally fractured Jurassic carbonate formation. These reservoirs contain multiple fluid types (gas-condensate and volatile oil) at near-critical conditions. Multiple scenario production forecasts are required to prepare an optimal development plan for the complex. Current compartmentalization understanding based on geological and engineering data led to 24 isolated segments for which up to 24 separate simulation models can be potentially built. Because of global production targets and constraints, these models cannot be run in isolation. A multiple reservoir simulations coupling controller that dynamically apportions global production targets among different reservoirs is used for the purpose. Compositions from different reservoirs are needed for surface facility design and operation. Compositional simulation is prohibitively computationally expensive for a multi-scenario production performance study for the NKJC. Black oil reservoir simulation is computationally far less demanding than compositional simulation. It does not, though, provide the detailed compositional information necessary for surface process modeling. We demonstrate that using a black oil delumping method based primarily on the compositional information generated when simulating the laboratory depletion process (CVD, CCE, DL) overcomes the main limitation of black oil reservoir simulation in the NKJC. The method enables the composition and component molar rates of a producing well from a black oil reservoir simulation to be accurately reconstituted. Full computational advantages of black oil modeling are obtained while preserving the reservoir details required for an accurate prediction of well and reservoir behavior. Comparison of results obtained from a compositional model to those obtained from a black oil model using black oil delumping shows excellent agreement. This study shows that black oil simulation with black oil delumping is a viable alternative to compositional simulation and fulfills the requirements for multi-scenario production forecasts in the NKJC.