Key geological and engineering technologies and research directions for shale gas exploration and development in western Hubei Province, China

Abstract

Multiple sets of marine shale sequences occur in western Hubei Province and its adjacent areas within the Middle-Upper Yangtze region, offering substantial resource potential. However, their shale gas preservation conditions differ significantly due to the heterogeneous porosity and fracture system resulting from multistage tectonic reworking. This necessitates developing region-specific evaluation systems and exploitation techniques. Drawing on previous application cases and guided by the research paradigm of geology-engineering integration, this study presents key technologies potentially applicable to shales in western Hubei Province, spanning from reservoir and sweet spot evaluation to fracturing scheme design and fracturing performance monitoring. Several insights are gained accordingly. In terms of pore evaluation, the pore heterogeneity caused by compaction and rebound can be quantified using ideal shape coefficients and fractal dimensions, both of which are influenced by structural deformations, thereby guiding reservoir classification. For seismic data interpretation, pre-stack elastic inversion and azimuthal anisotropy inversion can be employed as core techniques, overcoming the limitation of individual post-stack attributes in typically detecting only major faults. Furthermore, the inversion boundaries are constrained using log-seismic joint quality control and geomechanical simulation, contributing to enhanced reliability of sweet spot evaluation and efficient exploration in areas with complex structures. For fracturing scheme design, scientifically formulated well shut-in strategies, tailored to regional geological characteristics, are essential to activate the fracture-matrix imbibition effect. Parameters with vastly different scales used in the design, such as meter-scale fracture half-length and millidarcy-scale fracture conductivity, can be co-optimized using artificial intelligence (AI) algorithms such as the genetic algorithm (GA) and the simultaneous perturbation stochastic approximation (SPSA) algorithm. Dynamic monitoring of fracturing performance can be achieved using trace chemical tracer technology, thereby reducing target ambiguity caused by structural complexity. Research on shale gas in the structurally complex areas of western Hubei faces multiple challenges, spanning from basic geological understanding to development engineering. These challenges create an urgent need for deep interdisciplinary collaboration. Therefore, this study highlights research into geology-engineering integration, aiming to enhance the efficiency of shale gas exploration and development in western Hubei.