Abstract
Shale reservoirs are characterized by low oil and gas abundance, poor permeability, lower natural production capacity than the lower limit of conventional oil production, and the reservoir pressure decreasing rapidly. At present, for the development of such low-porosity, low-permeability resources, horizontal well drilling and hydraulic fracturing technologies are widely used, relying on long sections of horizontal wells in the reservoir, and the hydraulic fracture formed by wellbore stimulation as an "underground highway" for the flow of oil and gas from the deep reservoir to the wellbore. The combination of these two techniques can significantly increase the availability of hydrocarbon resources in the reservoir. Multi-stage hydraulic fracturing for horizontal wells is the crucial technology to achieve efficient recovery of shale oil. The results of downhole imaging, distributed fiber-optic temperature and acoustic monitoring in the field indicate that there are apparent non-uniform fracture propagation of each cluster during the fracturing process. Related research results also indicate that factors such as non-homogeneity of the reservoir and stress interference from multiple fracture expansion are the leading causes of the non-uniform expansion of hydraulic fractures. Therefore, how to make each fractured section expand equally and improve the coverage of fractures in the horizontal well section can be studied by a numerical simulation method, based on the fundamental theories of elasticity and fracture mechanics. The simulation results are consistent with the micro-seismic fracture monitoring results; this has obvious significance for accelerating the development of difficult-to-use oil and gas resources and securing the supply.
