A New Approach for Automatic Optimization of Complex Fracture Network in Shale Reservoirs

Abstract

Shale gas reservoirs have gradually become the main source for oil and gas production. The automatic optimization technology of complex fracture network in fractured horizontal wells is the key technology to realize the efficient development of shale gas reservoirs. In this paper, based on the flow model of shale gas reservoirs, the porosity/permeability of the matrix system and natural fracture system is characterized. The fracture network morphology is finely characterized by the fracture network expansion calculation method, and the flow model was proposed and solved. On this basis, the influence of matrix permeability, matrix porosity, fracture permeability, fracture porosity, and fracture length on the production of shale gas reservoirs is studied. The optimal design of fracture length and fracture location was carried, and the automatic optimization method of complex fracture network parameters based on simultaneous perturbation stochastic approximation (SPSA) was proposed. The method was applied in a shale gas reservoir, and the results showed that the proposed automatic optimization method of the complex fracture network in shale gas reservoirs can automatically optimize the parameters such as fracture location and fracture length and obtain the optimal fracture network distribution matching with geological conditions.

Tectonic Features of the Wufeng–Longmaxi Formation in the Mugan Area, Southwestern Sichuan Basin, China, and Implications for Shale Gas Preservation

“…The southern Sichuan Basin is weakly affected by the Cenozoic tectonic movement, whereas its southwest region has been strongly influenced [23,49,60,82,83]. Numerous studies suggest that wide-gentle folds related to the Indosinian-Yanshanian tectonic movement are helpful for shale gas preservation [49,77,84,85], such as shale gas of the Taiyang-Dazhai gas field and Jiaoshiba gas field is dominantly enriched at wide and gentle anticlines (Figure 1(c)), while shale gas of the Changning gas field is enriched at a low and gentle slope [12,16,25,[86][87][88]. Therefore, the key in shale gas exploration in the southwestern Sichuan Basin is to find an ideal zone similar to the MS in the Mugan area.…”