Striving to translate shale physics across ten orders of magnitude: What have we learned?

Mehmani, Yashar; Anderson, T. W.; Wang, Yuhang; Aryana, Saman A.; Battiato, Ilenia; Kovscek, Anthony R.

doi:10.1016/j.earscirev.2021.103848

Cited by 33 publications

(20 citation statements)

References 208 publications

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“…, fine scale processes control the dynamics at a larger scale, while, concurrently, large-scale variables constraint the system response at the fine scale ( e.g. , through boundary conditions and/or forcing factors). − Permeability alteration of shales due to precipitation and dissolution represent one such example, where chemical reaction at the micrometer/submicrometer scale can significantly alter effective properties of the rock at the millimeter/decimeter scale (bottom-up coupling); at the same time, permeability alterations affect the pressure field, the fluid distribution in the porous and network structures, the local velocity, as well as solute availability at subpore reactive interfaces (top-down coupling). Such two-way feedback mechanism across both spatial and temporal scales can dramatically affect and control the overall system behavior.…”

Section: Spatial Scaling Problemsmentioning

confidence: 99%

Chemical and Reactive Transport Processes Associated with Hydraulic Fracturing of Unconventional Oil/Gas Shales

et al. 2022

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Hydraulic fracturing of unconventional oil/gas shales has changed the energy landscape of the U.S. Recovery of hydrocarbons from tight, hydraulically fractured shales is a highly inefficient process, with estimated recoveries of <25% for natural gas and <5% for oil. This review focuses on the complex chemical interactions of additives in hydraulic fracturing fluid (HFF) with minerals and organic matter in oil/gas shales. These interactions are intended to increase hydrocarbon recovery by increasing porosities and permeabilities of tight shales. However, fluid–shale interactions result in the dissolution of shale minerals and the release and transport of chemical components. They also result in mineral precipitation in the shale matrix, which can reduce permeability, porosity, and hydrocarbon recovery. Competition between mineral dissolution and mineral precipitation processes influences the amounts of oil and gas recovered. We review the temporal/spatial origins and distribution of unconventional oil/gas shales from mudstones and shales, followed by discussion of their global and U.S. distributions and compositional differences from different U.S. sedimentary basins. We discuss the major types of chemical additives in HFF with their intended purposes, including drilling muds. Fracture distribution, porosity, permeability, and the identity and molecular-level speciation of minerals and organic matter in oil/gas shales throughout the hydraulic fracturing process are discussed. Also discussed are analysis methods used in characterizing oil/gas shales before and after hydraulic fracturing, including permeametry and porosimetry measurements, X-ray diffraction/Rietveld refinement, X-ray computed tomography, scanning/transmission electron microscopy, and laboratory- and synchrotron-based imaging/spectroscopic methods. Reactive transport and spatial scaling are discussed in some detail in order to relate fundamental molecular-scale processes to fluid transport. Our review concludes with a discussion of potential environmental impacts of hydraulic fracturing and important knowledge gaps that must be bridged to achieve improved mechanistic understanding of fluid transport in oil/gas shales.

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Section: Spatial Scaling Problemsmentioning

confidence: 99%

Chemical and Reactive Transport Processes Associated with Hydraulic Fracturing of Unconventional Oil/Gas Shales

et al. 2022

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“…Currently, only empirical formula can be fitted to the data obtained from adjacent scale models to approximately express their uniaxial coupling. In future, it is anticipated that the complicated relationships and information integration between two adjacent scales could be assisted by machine learning to realize complete coupling (Mehmani et al, 2021).…”

Section: Multiscale Characterization Of Fluid Flowmentioning

confidence: 99%

Multiscale and multiphysics inﬂuences on ﬂuids in unconventional reservoirs: Modeling and simulation

Cai

Wood

Hajibeygi

et al. 2022

Adv. Geo-Energy Res.

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Unconventional reservoir resources are important to supplement energy consumption and maintain the balance of supply and demand in the oil and gas market. However, due to the complex geological conditions, it is a significant challenge to develop unconventional reservoirs efficiently and economically. At present, unconventional reservoirs are extensively studied, covering a wide range of areas, with special attention to the multiscale characterization of pore structures and fracture networks, description of complex fluid transport mechanisms, mathematical modeling of flow properties, and coupled analysis with multiphysics fields. This work briefly describes the multiscale and multiphysics influences on fluids in unconventional reservoirs, and the modeling and simulation work conducted to analyze them, with the aim to provide some theoretical basis for enhanced recovery from these geo-energy resources. The present article also aims to enhance the community's knowledge of other potential utilizations associated with some unconventional reservoirs, specially related to environmentally-driven projects, including permanent greenhouse gas storage and cyclic underground energy storage.

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“…Furthermore, MPS methods may have difficulty capturing long-range and multiscale features [27][28][29]. This difficulty significantly impacts reconstruction of shale volumes due to the multiscale nature of shales [30]. Simulated-annealing methods incorporate multiple correlation functions and capture larger-scale features, but they can take hours or even days to generate large volumes [31,32].…”

Section: Synthesis Of Geologic Samplesmentioning

confidence: 99%

RockFlow: Fast Generation of Synthetic Source Rock Images Using Generative Flow Models

et al. 2020

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Image-based evaluation methods are a valuable tool for source rock characterization. The time and resources needed to obtain images has spurred development of machine-learning generative models to create synthetic images of pore structure and rock fabric from limited image data. While generative models have shown success, existing methods for generating 3D volumes from 2D training images are restricted to binary images and grayscale volume generation requires 3D training data. Shale characterization relies on 2D imaging techniques such as scanning electron microscopy (SEM), and grayscale values carry important information about porosity, kerogen content, and mineral composition of the shale. Here, we introduce RockFlow, a method based on generative flow models that creates grayscale volumes from 2D training data. We apply RockFlow to baseline binary micro-CT image volumes and compare performance to a previously proposed model. We also show the extension of our model to 2D grayscale data by generating grayscale image volumes from 2D SEM and dual modality nanoscale shale images. The results show that our method underestimates the porosity and surface area on the binary baseline datasets but is able to generate realistic grayscale image volumes for shales. With improved binary data preprocessing, we believe that our model is capable of generating synthetic porous media volumes for a very broad class of rocks from shale to carbonates to sandstone.

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Striving to translate shale physics across ten orders of magnitude: What have we learned?

Cited by 33 publications

References 208 publications

Chemical and Reactive Transport Processes Associated with Hydraulic Fracturing of Unconventional Oil/Gas Shales

Chemical and Reactive Transport Processes Associated with Hydraulic Fracturing of Unconventional Oil/Gas Shales

Multiscale and multiphysics inﬂuences on ﬂuids in unconventional reservoirs: Modeling and simulation

RockFlow: Fast Generation of Synthetic Source Rock Images Using Generative Flow Models

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