Field-Development Optimization of the In-Situ Upgrading Process Including the Ramp-Up Phase

Abstract

Summary Field-development optimization and optimization at the pattern scale are crucial to maximize the value of thermal enhanced-oil-recovery (EOR) projects. Application of a field net-present-value (NPV)-based pattern optimization algorithm honoring field-scale surface and subsurface constraints for in-situ-upgrading (IUP) projects has been described in the recent past. In this paper, we describe the development and application of a novel field-development-optimization capability, including the optimization of the ramp-up phase to accelerate the production to achieve a faster cash flow and high surface-facility utilization. We integrate this new capability into a robust field NPV optimization platform. A two-stagefield-development optimization algorithm is developed in this work. First, the steady-state pattern is optimized using the field-scale pattern optimization algorithm while honoring field-scale constraints and using a combined surface and subsurface performance-indicator-driven objective function. Ramp-up pattern designs are optimized separately using a solely pattern-scaleperformance-driven objective function in this stage. A preliminary pattern-delay time optimization follows next to precondition the problem for the subsequent field-scale optimization stage. The ramp-up pattern and pattern-delay times are optimized using a constant steady-state pattern in the second step of the algorithm. An appropriately penalized field-NPV-based objective function is used in this step to enforce field-scale surface and subsurface constraints. Optimization results on a realistic example application indicate that the time to oil-rate plateau could be significantly reduced on the order of multiple years while honoring the surface production constraints. This requires the use of an optimized ramp-up pattern in conjunction with the optimal steady-state pattern. The ramp-up pattern is approximately two patterns wide and features an increased heater density to deliver production acceleration. It is also notably more robust against the effects of subsurface uncertainties.