ИСТИНА

Many applied research and technical problems require knowledge of conditions of fracture propagation at microscale, taking into account material heterogeneity in terms of void space structure and fabric. Examples of the tasks are optimization of hydraulic fracture simulation of unconventional reservoirs rock, maximization of voids connectivity in near-wellbore zone due to application of external stress at microscale, quality validation of elastic-plastic model using results of laboratory geomechanical testing of rock samples and mitigation cracking and disintegration processes in material science. In this work authors study fracture propagation at microscale in heterogeneous materials in particular hydrocarbon reservoir rocks in order to increase efficiency of hydraulic fracture stimulation of tight gas fields and maximize production of oil and gas from connected void network. The study consists of 3 main steps: building a dataset containing petrophysical, geomechanical and mineral data, preparation and initialization of microscale 2D and 3D digital rock models and numerical mechanical simulations of fracture propagation in digital rock models [1]. In the presented study authors conduct the multimodal segmentation and registration of 2D QEMSCAN and 3D X-ray micro-CT data in collaboration with the University of New South Wales and Australian National University [2] in order to develop a workflow for constructing 3D mineral digital rock models and its embodiment. The research also includes preparation of a database of mechanical properties (elastic, plastic and strength) of main rock-forming minerals of the studied reservoir. The next logical step is a comprehensive survey of existing mechanical simulators for fracture propagation in heterogeneous materials at microscale and test results of one selected candidate are presented. In summary, authors have taken steps to prepare 3D mineral models of investigated heterogeneous materials and mechanical simulations of these models. Future work consists of building 3D integrated model [3] based on the granular composition, structure and mechanical properties of investigated rock samples, numerical simulation of 3D fracture propagation at microscale and experimental validation of numerical models on experimental mechanical properties and fractures. [1] Nachev, V. et al. Development of an integrated model of rock fracturing at nano/microscale // Skoltech & MIT Conference "Shaping the Future: Big Data, Biomedicine and Frontier Technologies". 2017. [2] Wildenschild, D., Sheppard, A. P. X-ray imaging and analysis techniques for quantifying pore-scale structure and processes in subsurface porous medium systems // Advances in Water Resources. 2013 – 217-246. [3] Sok, R. M. et al. Pore Scale Characterization of Carbonates At Multiple Scales: Integration of Micro-CT, BSEM, And FIBSEM // Petrophysics. 2010. № 6. – 379–387.