Innovative Alternative to Full-Field Compositional Modeling-Case Study of the North Kuwait Jurassic Complex

Abstract

Summary The North Kuwait Jurassic complex (NKJC) consists of six fields with four potential reservoirs in a naturally fractured Jurassic carbonate formation. Current understanding of the complex has led to 12 subdivisions of the area and potentially 48 separate compartments (segments) in the complex. These subdivisions are defined by fault boundaries supported by a combination of variations in fluid composition, initial pressures, and free-water levels estimated from capillary pressure and log saturation data. Multiscenario production forecasts based on integrated full-field modeling were needed in the process of building a field-development plan (FDP) for the NKJC. An integrated asset modeling (IAM) framework is adopted in which multiple separate reservoir models are coupled through global constraints to meet gas-delivery targets. We present the results of a feasibility study to select the optimal modeling strategy for the complex. We discuss available options to simulate multiple reservoirs, which, although isolated based on the current understanding of compartmentalization, need to meet global production targets. We show that using multiple-reservoirs integration through a controller to couple the separate reservoir models through global production targets/limits provides an optimal simulation framework for the NKJC—the flexibility and computational efficiency of multiple segment models and the comprehensiveness of full-field simulation modeling. The solution uses a black-oil delumping technique to obtain compositional wellstreams while running black-oil simulation models. The feasibility study demonstrated that black-oil delumping enables the composition and component molar rates of a producing well from a black-oil reservoir simulation to be reconstituted accurately. Comparison of results obtained from a compositional model to those obtained from a black-oil model using black-oil delumping shows excellent agreement. The adopted simulation framework provided us with all the benefits of a compositional full-field simulation model while adding two advantages (i.e., computational speed and flexibility). Full computational advantages of black-oil modeling are obtained while preserving the reservoir details required for an accurate prediction of well and reservoir behavior.