# A Study on the Remaining Reserves of the Weiyuan Shale Gas Block in Three-Dimensional Development
## 5 Countermeasures to Improve Recovery  
The H8 platform is located in the south wing of the Austro-topped structure in the Weiyuan tectonics, with three wells in each of the upper- and lower-half branches of the platform, with a spacing of 400 m, and a horizontal section length of 1300 to 1600 m, of which wells W1, W2, and W3 are the three wells in the lower-half branch, and the rest are the wells in the upper-half branch. The H8 platform has been under production and development since 2016, with an upper-half branch formation pressure of approximately 32.59 MPa, cumulative gas production of 2.16 \(\times\) 10\({}^{8}\) m\({}^{3}\), remaining geological reserves of 8.62 \(\times\) 10\({}^{8}\) m\({}^{3}\), and recovery factor of 18.8%; a lower-half branch formation pressure of approximately 38.16 MPa, cumulative gas production of 1.98 \(\times\) 10\({}^{8}\) m\({}^{3}\), and remaining geological reserves of 10.07 \(\times\) 10\({}^{8}\) m\({}^{3}\), and recovery factor of 16.4%. The production effect of the lower-half branch is poor, and the production and recovery factors are lower than those of the upper-half branch, but the remaining geological reserves are larger than those of the upper-half branch, which shows that the remaining reserves of the lower-half branch of the platform have more space for potential exploration. Therefore, the numerical simulation study of three-dimensional development is carried out using the lower-half branch of the H8 platform as an example.  
The numerical simulator was selected from Schlumberger's Petrel RE software, which has a reservoir module for shale gas that provides a good simulation of horizontal wells and artificial fracturing techniques (including time-varying characteristics of hydraulic fracturing, such as diffusivity, conductivity, permeability, and pore volume). In this paper, the wellheed pressure data of the three wells in the lower half of the H8 platform are used to calculate the bottom-hole pressure of the gas well. Then, based on the three-dimensional geological model of the Weiyuan block established above and 8 years of actual production data, the bottom-hole pressure is fitted to verify the accuracy of the geological model. The bottom-hole flow pressure and production prediction of a single shale gas well is also carried out on the basis of the existing geological model. Based on the historical fitting results, the production capacity prediction of shale gas wells is carried out through the gas reservoir engineering method and numerical simulation method, based on the integrated software of gas reservoir engineering. According to the gas reservoir engineering prediction results, based on the current gas well production, W1, W2, and W3 continue to produce for another 35 months, of which the capacity prediction results of the W1 well are compared with the prediction results of the numerical model, and its error is the largest at 5.2%. The prediction results of the W3 well are analyzed for error, which is in line with the results of the numerical simulation, with an error of only 0.9%, and the prediction results can basically be maintained at an error of 0.9-5.2%, which can validate the accuracy of the numerical simulation results.