Integrated Asset Modeling of a Coupled Reservoir for Production Optimization

Abstract

Abstract This thesis presents an approach for coupled subsurface and surface network facility optimization of oil production and CO2 sequestration, utilizing CO2 in enhanced oil recovery. A field-scale integrated asset model of the mature Farnsworth field is developed with a surface-coupled history-matched compositional numerical reservoir simulation model and operating conditions optimized. The reservoir flow model was constructed based on extensive geophysical, geological, and engineering data from the Farnsworth Field Unit. Peng-Robinson equation of state parameters were tuned to field laboratory measured fluid properties. The model was calibrated to the primary and secondary recovery phases and subsequently to the tertiary recovery phase. Once a good match was achieved for the tertiary phase, an optimization model was designed with the goal of maximizing oil recovery and CO2 storage. A sensitivity analysis was conducted to determine the most impactful parameters among recycled and purchased CO2, Water-Alternating-Gas (WAG) cycle and ratio, Tubing Head Pressure (THP) of injectors and producers, separator pressure and gas compressor injection rate. A Radial Basis Function Neural Network was used to create the proxy from training data obtained from numerous simulations. A Particle Swarm Optimubizer was used to find the optimum operating conditions of the surface facility network and maximize oil recovery and CO2 storage. The optimized values provide a more efficient use of CO2 in incremental oil recovery. This results in higher cumulative oil recovery while the CO2 remained trapped in the reservoir and/or in closed loop. The conversion of water injectors to CO2-WAG injectors based on optimized development strategy improved oil production by increasing the sweep efficiency of the water in the region. The inclusion of surface facilities is necessary in this study to optimize oil production with an increased accuracy of life cycle assessments for CO2-EOR processes. Integrated Asset Modeling gives access to operating conditions and surface facility constraints that would otherwise be left to assumptions or ignored. This paper presents a robust framework for optimizing surface operating conditions for maximizing oil recovery based on existing field capacity.