A method for predicting production capacity based on a shale gas content test

At present, there is no way to predict shale gas well production capacity at home and abroad. There are many disputes because the gas content test results are different from later production. Through the analysis of the desorption process, the question as to why the output of many shale gas wells with similar gas volume is greatly different was preliminarily answered. Gas content data is not enough to characterize gas-bearing capacity, which should be taken into consideration together with the desorption process, such as desorption rate and free gas content factors. A new coefficient was defined, namely the gas content index:gas content index=desorption rate×free gas content×total gas volume. The internal meaning of the gas content index was also analyzed. Some relevant factors of shale gas production were screened through field gas content tests. Two factors, gas content index and pressure coefficient, which have an obvious correlation with daily production, were selected. A multiple regression model was established in view of these two factors. A daily output prediction formula was obtained. Daily output=0.146 7×pressure coefficient^7.2×gas content index+0.086 4. The reliability of the model was verified on site, so that the capacity of shale gas wells can be preliminarily predicted after the completion of field gas content testing.