Justifying Method of Enhancing Oil Recovery of Multi-zone Reservoirs Including Hydrodynamic Connected Reservoirs

Objectives: This research deals with field development of multi-zone reservoirs including two or more connected reservoirs differing greatly in their reservoir parameters. Development of such fields is characterized by uneven recovery of reservoir reserves. Methods: Recovery efficiency for low-permeability reservoir decreases drastically, in the case of water breakthrough to the bottom hole of the production well through a high-permeable reservoir and a significant part of the reserves is not drained. The key reason is existence of inter-reservoir cross flows arising due to high pressure differentials between the reservoirs. For the purpose of enhancing recovery efficiency of multi-zone reservoirs, modern methods of enhancing oil recovery may be considered. Findings: At the same time, most of the methods do not solve the problem of inter-reservoir cross flows efficiently, thus, providing no increase in drainage of the low-permeability reservoir. The authors provided a new approach based on the application of technology of dual production and injection of water containing suspended particles. This approach ensures a significant reduction in volumes of inter-reservoir cross flows, owing to the use of selective impact of water containing mechanical suspended particles in filtration of reservoirs that differ in reservoir parameters. The composition, size and concentration of water particles are determined at the stage of laboratory tests, using core samples taken from the productive reservoirs. As a result of 3D hydrodynamic simulation of this approach, using sector and full-scale simulation models, a possible increase in the forecasted oil recovery in a wide range of reservoir properties was shown, factors that affect method efficiency were determined. Applications/Improvements: This approach may be applied to enhance oil recovery of multi-zone reservoirs including hydrodynamic connected reservoirs. Keywords: Commingled Oil Production, Connected Reservoirs, Formation Damage, Suspended Particles, Water Injection, Water flooding