CT Image-based reconstruction modeling and numerical analysis of hydrofracturing behaviours of heterogeneous reservoir glutenites considering hydro-mechanical coupling and leak-off effects

Hydrofracturing technology has been widely used to stimulate the tight hydrocarbon reservoirs that usually comprise heterogeneous glutenites. Distribution patterns and physical properties of heterogeneous particles in glutenites may affect fracture initiation and propagation in hydrofracturing process. Hydro-mechanical coupling and leak-off are essential characteristics of this process and need to be properly addressed in numerical simulation, which plays an important role in quantitatively evaluating the efficiency of this technology. Due to the challenges in accurately representing the complex structure and physical properties of heterogeneous glutenites as well as hydraulic-driven crack propagation, however, the hydro-mechanical coupling, leak-off, and material heterogeneity have not yet been handled satisfactorily. To overcome these challenges, we use the finite element-discrete element method to simulate the hydraulic fracturing of heterogeneous glutenites, considering hydro-mechanical coupling and leak-off effects. The numerical models are constructed using geometrical and physical parameters that were extracted from natural heterogeneous glutenites using computed tomography, X-ray diffraction, and triaxial tests, based on image processing and reconstruction approaches. The models are composed of hydraulic fractures and microscale pores, and Darcy's law was integrated within the model to govern fluid leak-off; this is a non-traditional approach to leak-off effects. The coupled finite element-discrete element approach is used to determine the fracturing behaviours of image-based heterogeneous reconstruction models. The fracturing crack propagation and distribution patterns of homogeneous and heterogeneous models under various horizontal in-situ stress differences are characterised by fractal theory, and the models are compared to assess the influences of material heterogeneity and in-situ stresses on the hydraulic fracturing of heterogeneous glutenites. This report intends to give a brief introduction of recent exploration and progress.