Recent Advances in Multiscale Digital Rock Reconstruction, Flow Simulation, and Experiments during Shale Gas Production

Abstract

The complex and multiscale nature of shale gas transport imposes new challenges to the already well-developed techniques for conventional reservoirs, especially digital core analysis. Multiscale complicated pore systems and distinctive properties limit most reconstruction methods not applicable. High-precision imaging experiments play a key role in the characterization of pore structures and mineral components. While the exhilarating breakthroughs in physical experimental methods and hybrid superposition methods have made significant achievements in shale digital rock reconstruction, rapidly evolving deep learning methods also present a promising option. Benefiting from the digital rock techniques, the pore-scale flow of shale gas can be directly simulated based on digital rock or indirectly modeled using the pore network model. It is precise and realistic to investigate the shale gas flow at the pore scale considering the desorption, surface diffusion, and slippage in nanopores. In this paper, we reviewed the recent advances in off-mentioned methods and processes and presented a hand for the research in this field.

Advances and Prospects of Supercritical CO2 for Shale Gas Extraction and Geological Sequestration in Gas Shale Reservoirs

“…The proportion of adsorbed gas in shale rocks can range from 20% to 85% . During the later stages of shale gas extraction, gas production is primarily attributed to adsorbed gas . Thus, understanding the adsorption mechanism of shale gas is crucial to determining the microscopic fugacity pattern of shale gas and providing support for the reasonable and effective exploration and development of shale gas.…”

Minireview on Porous Media and Microstructure Reconstruction Using Machine Learning Techniques: Recent Advances and Outlook

“…Increasing demands for studying shale gas transport through pore-scale simulations call for special attention to be given to the digital reconstruction of the complex, multiscale, and anisotropic nature of the shale rocks. Despite the immense challenges, efforts have been made to leverage deep learning methods for this task, some of which are reviewed by Yang et al 115 and Jiang et al 116 To this end, Zha et al 117 proposed WGAN-GP, a variant of deep convolutional GAN with Wasserstein loss function and gradient penalty, to reconstruct shale rock nano-CT images. As previously mentioned, this modified loss function is stated to be helpful to the stability of the training and the reconstruction quality.…”

Pore Scale Characterization of Gas–Water Flow in Heterogeneous Layered Sandstone

“…3,4 The phenomenon of fingering, which results in the creation of dominant fluid channels preferentially in the high permeability layers and can cause substantial interlayer interference, is caused by the variety of vertical permeability in sandstone reservoirs. 5,6 Additionally, because sandstone gas reservoirs frequently contain some stratigraphic primary water, it is relatively simple for early water to arise throughout the production process, which negatively impacts the exploitation of gas resources. 7,8 The distribution of fluids and recovery of oil and gas resources are significantly impacted by the heterogeneity of sandstone reservoirs.…”

“…Sandstone reservoirs are important production reservoirs for oil and gas resources with broad prospects for gas reservoir development. Additionally, sandstone reservoirs are significant locations for the geological storage of carbon dioxide due to their vast distribution area and high capacity. , However, sandstone reservoirs have a significant degree of layered heterogeneity, bedding, and interlayer abundance. , The phenomenon of fingering, which results in the creation of dominant fluid channels preferentially in the high permeability layers and can cause substantial interlayer interference, is caused by the variety of vertical permeability in sandstone reservoirs. , Additionally, because sandstone gas reservoirs frequently contain some stratigraphic primary water, it is relatively simple for early water to arise throughout the production process, which negatively impacts the exploitation of gas resources. , The distribution of fluids and recovery of oil and gas resources are significantly impacted by the heterogeneity of sandstone reservoirs. − To better understand the features of gas and water flow, it is crucial to take the heterogeneity of the sandstone reservoirs into consideration.…”