On hot water flooding strategies for thin heavy oil reservoirs

Abstract

Abstract Cold production methods for heavy oil resources in Western Canada yield recovery factors averaging about 10% and as yet, there are no commercially successful technologies to produce oil from these reservoirs with recovery factor greater than 20%. This means that the majority of oil remains in the reservoir. The objective of this study is to determine technically and economically feasible recovery processes for thin heavy oil reservoirs by using a simulated annealing algorithm. The results reveal that high injection pressure is critical to a successful hot water flooding strategy. Also, they show from a thermal efficiency point of view that it is most efficient to adopt an injection temperature profile where the injection temperature starts high earlier in the process and ends at lower water temperature. The lower temperature injection at later stages of the recovery process partially recovers the heat stored in the reservoir matrix and therefore increases the overall heat utilization efficiency. A sensitivity analysis shows that the permeability distribution affects the performance of the hot water flooding process most significantly. The existence of a higher permeability zone in the lower part of the reservoir leads to earlier oil production and water breakthrough. High permeability was found to lead to more oil and water production in the early stage of operation and achieved the best economic performance. The low permeability case exhibited relatively low oil production volume. Although it has the lowest cumulative injected energy to oil produced ratio, poor oil production renders the operation process uneconomic. Given the volume of currently inaccessible thin heavy oil resources, the optimized strategies developed here provide important guidelines to convert these resources to producible reserves.