3D Digital Mineral Mechanical Modeling of Complex Reservoirs Rocks for Investigation of Fracture Propagation at Microscale. Unconventional Resources Technology Conference (URTec), Denver, 2019тезисы доклада
Аннотация:Reliable forecast of fracture propagation during hydraulic fracturing operations in complex reservoirs rocks is a complicated task. It is tightly coupled to studying their mechanical parameters, microstructure at various scales and elastic strength characteristics of rocks. The goal of this work is to investigate and evaluate the mechanical parameters and boundary conditions of the studied intervals at microscale that need to be created in unconventional rock reservoirs in order to obtain an extensive network of non-main fractures.
The scope of the study is in integrating results of microstructural investigations of reservoir rock samples at microscale and dry-state geomechanics.
The study addresses the problem of hydraulic fracture optimization by suggesting stress-strain conditions in rocks at which main fractures would have a number of high-branching non-main fractures in order to maximize drainage zone.
In order to achieve the goal, the authors propose a method which contains the following workflow: building a dataset containing petrophysical, geomechanical and mineral data, preparation and initialization of 2D and 3D microscale digital rock models and numerical simulations of their stress-strain states and fracture propagation in them.
Authors conduct a set of experimental investigations of mechanical parameters of rock samples, CT before and after the formation of fractures, quantitative analysis of rocks with an integrated automated mineralogy and petrography solution. Then the preparation of a database of mechanical properties (elastic, plastic and strength) of main rock-forming minerals of the studied rock was done. Next step was the multimodal segmentation and registration of 2D QEMSCAN and 3D X-ray micro-CT data in order to develop a workflow for constructing 3D mineral digital rock models and its embodiment. Finally, a grid was built on 3D digital model of segmented rock and loaded into a mechanical simulator where each grain was assigned the appropriate mechanical properties.
Within the study authors are developing a workflow targeted to reliable forecast of branched fracture propagation in complex reservoirs rock samples at microscale. The workflow in based on an integrated analysis of quality laboratory geomechanical data, building of 3D digital rock models based on measured data and numerical mechanical simulations.
The proposed workflow was applied to one of the most promissing unconventional tight gas formations in Russia with pore dimensions down to tens of nanometers. In the result of numerical simulations, fracture networks for different loading conditions were obtained. This capability allows picking reasonable stress-strain conditions that sustain the highest degree of formation fracturing.
The workflow can be applied to different domains such as maximizing 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.
The prosed work allows to increase the efficiency of hydraulic fracturing stimulation of unconventional hydrocarbon reservoir and maximize production from isolated pore systems.
A novelty of the workflow is in the development of approach which will allow to describe 3D fracture propagation in highly heterogeneous materials or reservoirs rocks taking into account its void space structure and fabric.