Abstract: Hydraulic fracturing is currently the main method of exploiting tight gas and oil. The pump-stop pressure and flow-rate data measured during hydraulic fracturing process contains a great deal of important information, such as the formation pressure, permeability and fracture half-length. These parameters are significant judgment to decide post-fracturing mining system. A new method of pump-stop data-inversion analysis method based on digital filtered pump-stop flow-rate and density-changing pressure data of hydraulic fracturing was presented. Firstly, the ground pressure was converted to the well bottom pressure according to the vertical pipe flow theory. The obtained bottom pressure data, also known as pump-stop pressure data, was processed through the FIR filter to eliminate the interference of water hammer and other noise signals. Finally, the filtered data, which contains the information of formation permeability and initial pressure, was processed according to vertical fracture well test analysis. This new method has been proved reliable by comparing it with pressure build-up, making real-time evaluation of fracture and formation information possible.

Key words: digital filtering, hydraulic fracturing, well test analysis, fracturing evaluation