Estimation of Interwell Connectivity of a Single Layer in a Stratified Reservoir Based on Physical Constraints

After 60 years of water flooding development, Daqing oilfield has entered the stage of “double extra high” development. The three major contradictions are highlighted, and it is urgent to improve the development effect of water flooding. The estimation of the interwell connectivity of every single layer in a stratified sandstone reservoir with water flooding is the key to the adjustment of an injection-production well and the improvement of the water flooding development effect. However, this is one of the most challenging aspects because of the heterogeneity of the stratified reservoir and the complexity of the well patterns in production. In this research, a quantitative data-driven evaluation method for single-layer interwell connectivity based on physical constraints is proposed using the dynamic resistivity model (DRM) and the capacitance resistivity model (CRM). The dynamic resistivity model in a single layer considers the variation of the water saturation is established to quantitatively describe the difference in the water injection between injection wells and production wells. Then, a high-efficient method for constructing the physical constraints of each injecting well is proposed based on the DRM, and the parameters of the CRM of the wells can be optimized by using of EnKF. Therefore, the quantitative evaluation of the connectivity of each injection-production direction in a single layer is realized. Homogeneous and heterogeneous conceptual models are established with FrontSim and compared with the SCRM and PC-SCRM models. It is shown that the absolute error of this method is about ±5% for the evaluation of single well connectivity. In this research, the method described can be applied to horizontal and longitudinal heterogeneous multi-layer sandstone oilfields and the fast quantitative evaluation of single-layer interwell connectivity can be achieved. This method has broad application prospects in water flooding development and the intelligent oilfield construction of a multi-layer sandstone oilfield.