Fracture system in shale gas reservoir: Prospect of characterization and modeling techniques

The quality and production of shale gas are directly dependent on the development of fractures. Especially in large-scale fracturing development, natural and hydraulic fractures play significant roles. Consequently, there is a growing demand for the quantitative characterization of shale gas reservoir fractures and the development of geological modeling technology. Structured and non-structural fractures make up mainly of natural fractures in shale gas reservoirs. External factors such as tectonic stress control the former, while internal factors such as rock and mineral composition control the latter. Fractures of different scales have a variety of primarykey characterization parameters and prediction techniques. Natural fracture models for shale gas reservoirs are predominant on large-scale and mesoscale fractures. In the numerical simulation, hydraulic fracture modeling is explored in greater detail. This paper discusses the design and explains the main directions of natural and hydraulic fracture modeling in shale gas reservoirs from the aspects of the multi-information application, multi-technology integration, and multi-disciplinary crossing considering the current and potential technology and production requirements. Natural fractures require fusion characterization and modeling on a multi-scale and multi-method basis. Hydraulic fracturing necessarily involves the fusion of multiple information constraints of forwarding and inverse simulation. Furthermore, using the principle of geology-engineering integrated modeling, this paper describes the inner relationship and development of the geological model of a shale gas reservoir from three aspects of model type, data integration, and model fusion to guide the efficient development of shale gas reservoirs.