Productivity performance of open hole horizontal gas well for low permeability gas reservoirs

Abstract

This study aimed to develop a novel productivity model for an open-hole horizontal well in a low permeability gas reservoir (LPGR). First, the permeability and pressure gradient were revised by the slippage factor, stress-sensitivity coefficient, and startup pressure gradient (SPG). The mirror reflection method was used to solve the influence of top and bottom boundaries on the seepage field, and we can obtain the internal seepage resistance of the well. Second, the Joukowski transformation method can solve the influence of horizontal boundary on the seepage field so that external seepage resistance can be obtained. Finally, by taking the high-velocity non-Darcy effect (NDE) into account, a novel model, which is suitable for an open-hole horizontal well (OHHW) in low permeability gas reservoirs with a high stress-sensitivity coefficient, was developed. The model was verified using data from wells G3 and G4, and the prediction relative errors of the absolute open flow (AOF) of these two wells were only −0.14% and 0.37%, respectively. Then, by comparing with other different models, the results demonstrate that the model constructed in this work has a clear superiority in productivity analysis; it has some guiding significance for the development of open-hole horizontal gas wells in low permeability gas reservoirs.