Analysis of Diagnostic Fracture Injection Tests for Shale Gas Wells

Formation pressure estimation of shale gas wells is one of the key factors affecting production prediction of gas wells, and diagnostic fracture injection test analysis is an important means to accurately obtain formation pressure parameters. In this paper, through the establishment of shale gas well diagnostic fracture injection test model, taking ChangNing shale gas field as an example, the actual test data of pre-production gas wells are fitted. Then analysis the change law of pressure transient curves and the model fitting results with conventional analysis method comparing with the results - G function diagnosis curve method to explain, optimizing fracture closure point selection mode, this paper proposes a new method to determine fracture closure point: when G derivative curve begins to deviate from the initial linear trend, correct selection of closed point, to obtain accurate formation pressure coefficient, formation pore pressure of reservoir parameters such as reservoir. At the same time, the improved method is used to evaluate the reservoir parameters of the actual gas wells in ChangNing, providing theoretical guidance for the subsequent fracturing construction and production.