A Review of Flow Mechanism and Inversion Methods of Fracture Network in Shale Gas Reservoirs

Abstract

The pore structure of shale gas reservoirs has strong heterogeneity, and the flow mechanism in multiscale media is complex. The fracture network of hydraulic fracturing is significantly affected by reservoir in situ stress, rock mechanical properties, and natural fracture distribution. At present, there is no efficient and accurate inversion method for fracture networks. Accurately describing fracture network morphology and flow capacity distribution of induced fracture is an important basis for production analysis, fracturing evaluation, and production plan. This article focuses on the hot issues of shale gas development, from three aspects: flow parameter characterization method of organic/inorganic matter, multiscale mass transfer simulation of shale gas reservoir, and inversion method of fracture network morphology and flow capacity, to introduce relevant research progress in detail. At the same time, the advantages and shortcomings of current related researches are compared and analyzed. Based on this, the key scientific problems existing on flow mechanisms and inversion method of fracture network in shale gas reservoirs are proposed, which can provide guidance for further research.

Research Advance on the Diagnosis Technology of Hydraulic Fractures in Shale Reservoirs

“…The production data analysis method mainly includes an analytical/semi-analytical model and a numerical simulation model (Stalgorova and Mattar, 2012;Huang et al, 2021).…”

“…However, shale reservoirs have complex mineral composition, natural fractures, and bedding structures. The existing fracture diagnosis technology is not mature enough, and there are problems of low efficiency and poor simulation accuracy, which cannot accurately match the actual fracture network morphology (Huang et al, 2021). Fracture diagnostic technology is the main approach to determine fracture network morphology.…”

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

“…Network in Shale Gas Reservoirs [39], the microunits in the reconstruction area are intercepted, and the physical flow model of orthogonal discrete fracture coupled with dual-media matrix block is established [40]. As shown in Figure 1(b), the fracture network distribution in the actual reservoir reconstruction area is relatively complex, and it is typical as a vertical cross fracture network.…”

Research on the data-driven inter-well fracture channeling identification method for shale gas reservoirs

“…Aleksandrov et al (2018) and Wu et al (2017) used this method for fracture analysis. However, with the advancement of technology, it has been found that the error of microseismic monitoring technology is large, and the actual fractures are only between 30% and 70% of the monitoring results (Huang et al, 2021a). The credibility of evaluating fracture channeling using microseismic monitoring can be greatly reduced.…”