Production optimization for alternated separate-layer water injection in complex fault reservoirs

Abstract

Complex reservoirs possess some principal characteristics, such as strong geological heterogeneity, faults and multi-layers, etc. They can exert significant effects on the flow performance of water flooding vertically and horizontally. For most large-scale and well-connected reservoirs, water injection wells generally adopt manual adjustment method or intelligent well technology to control the water injection volume of a single well. However, these technologies are associated with high costs, and it is not a trivial task to obtain an optimal injection-production control for some complex reservoirs with small blocks or strong heterogeneity. More importantly, most complex fault block reservoirs have experienced multiple rounds of well pattern infilling adjustment in the development process, with large well pattern density, as well as because of complex structure, fault development and single injection production form of fault block reservoir. In view of the unbalanced vertical production of fault block reservoirs in high water cut stage, the alternative injection production mode is proposed to minimize the interlayer interference and achieve stable production under unstable injection production. However, the key parameters of the alternative injection production method are not clear and need to be optimized. Facing this situation, a new method for the injection-production optimization is proposed in this paper. This technology use underground regulator which can alternately open and close the different layers. Additionally, the heterogeneity of permeability is considered and a uniform displacement of water in each flooding unit is realized by adjusting the regulators of injectors and producers. By using this method, a series of measurements such as on-off time and injection volume can be chosen as decision variables. Hence, the commercial simulator and the optimization theory algorithm are used to optimize and adjust the alternative stratified water injection technology. Additionally, this method can be combined with field practice, save the cost of measurement and adjustment, and be easy to operate. This method can be combined with field practice, save the cost of measurement and adjustment, and be easy to operate. Detailed parameter optimization and results are presented with an example to prove the efficacy of the proposed methodology. The results show that the method proposed in this study can be successfully applied to optimization of well control and improve the reservoir development significantly.