Future Performance Prediction of a Naturally Producing Oil Reservoir Using History-Matched ECLIPSE Simulation: Development Implications

Abstract

In this study, reservoir simulated-model history matching, trial and error technique, is undertaken to improve understanding of BB oilfield reservoir dynamic behavior and provide a robust basis for production forecasting that informs development implications. The work steps started with; building Eclipse dynamic simulated-model through generating static model using Petrel software, and followed by upscaling of fine grid model, representation of the reservoir rock properties, characterization of the fluid properties and rock-fluid physical data, well modeling, production history validation. The next step is calibration of observed production data for simulated-model history matching, followed by reservoir performance prediction, evaluation, and development implications. The studied BB reservoir formation primarily consists of medium-to coarse-grained sandstones interbedded with shale layers. In addition, BB oilfield consists of three vertical oil wells, BB-1, BB-3, BB-4, and it produced 9 MMSTB in cumulative through approximately 31 years. The BB Field simulated-model prediction estimated that the field cumulative natural oil will be 12.48 MMSTB in 2034. Moreover, the field natural production rates are expected to range 143-400 STB/D, associated with very high GOR (4-8.1 MSCF/STB), small water cut (less than 4%), and relatively moderate bottom-hole pressures (3800-4200 psi). The most likely reason behind the extreme GOR is the heavy depletion-driven gas liberation, due to reservoir gas saturation passes the critical gas saturation (Sgc), eliminating oil production as pressure drops. The study recommended some measures to manage field GOR and improve oil recovery including; GOR control, drilling infill horizontal wells, and pressure maintenance.