A Novel Productivity Calculation Method for Gas Reservoirs of Qixia Formation, Shuangyushi Block, Northwestern Sichuan

In Shuangyushi block, northwestern Sichuan Basin, most gas reservoirs of Qixia Formation are characterized by super deep burial depth, high pressure, low porosity, and strong heterogeneity, bringing about difficulty in implementing productivity testing for gas wells. Moreover, there is a big error in an application of the common-used one point method to the early development stage of high-pressure gas reservoirs. So, it’s essential to develop a novel productivity calculation approach suitable for the Qixia gas reservoirs in Shuangyushi block in order to guide a rational proration of gas wells. However, a development of high-pressure and low-porosity gas reservoirs is sensitive to stress sensibility and high-speed non-Darcy effects, further affecting their development results. In this study, based on previous achievements, one method to calculate the productivity of gas reservoirs with abnormally high pressure, which takes full consideration of stress sensitivity, high-speed non-Darcy effects, and reservoir heterogeneity, is put forward, and some factors affecting the productivity are quantitatively analyzed. Results show that, due to high calculation accuracy, this method is very useful to calculate absolute open flow (AOF) of gas wells without productivity in these Qixia gas reservoirs with super deep burial depth and high pressure, and may guide an efficient development for similar ones.