Waterflood Direction and Front Characterization with Multiple Methods: A Case Study in Changqing Oilfield, China

Abstract

Abstract Due to the effect of reservoir heterogeneity and micro-fractures in low permeability reservoirs, effectively characterization of waterflood direction and front has become a tough issue under high water-cut condition. In order to achieve better understanding of such a complex problem, a workflow, containing statistical and numerical techniques, is developed to characterize waterflood direction and front distribution in Changqing Oilfield by employing both flow rates and bottom-hole pressure (BHP) data. The workflow includes four steps: first, dynamic analysis is used to qualitatively investigate the relationships between injector and producers. Then, constraint multiple linear regressions (MLR) method is applied to calculate the interwell connectivity coefficients, which was used to quantitatively describe the waterflood direction by injection and production rates. Based on the results of the two former steps, we can adopt numerical well testing as our third step to deal with flow rates and BHP data to characterize the waterflood direction and front. Finally, streamline method is employed to simulate the waterflood front and high-permeability channels distribution based on the outcome of the three preceding techniques. We apply this workflow to the well group W16 in Changqing Oilfield, and the results show that we can acquire better understanding of waterflood performance under high water-cut condition, including interwell connectivity, waterflood direction, and waterflood front distribution. Compared to individual method, the proposed workflow can offer more perspectives and ways to make a comprehensive and deep investigation of the waterflood reservoir. With the help of the information obtained by this workflow, operators could make more reasonable decisions on waterflood management such as well pattern optimization and injection-production parameters adjustment.