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Li K, Hu R, Wang T, Yang Z, Chen YF. Buoyancy-Driven Dissolution Instability in a Horizontal Hele-Shaw Cell. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:4186-4197. [PMID: 38358822 DOI: 10.1021/acs.langmuir.3c03219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
The dissolution of minerals within rock fractures is fundamental to many geological processes. Previous research on fracture dissolution has highlighted the significant role of buoyancy-driven convection leading to dissolution instability. Yet, the pore-scale mechanisms underlying this instability are poorly understood primarily due to the challenges in experimentally determining flow velocity and concentration fields. Here, we integrate pore-scale simulations with theoretical analysis to delve into the dissolution instability prompted by buoyancy-driven convection in a radial horizontal geometry. Initially, we develop a pore-scale modeling approach incorporating gravitational effects, subsequently validating it through experiments. We then employ pore-scale numerical simulations to elucidate the 3D intricacies of flow-dissolution dynamics. Our findings reveal that a simple criterion can delineate the condition for the onset of buoyancy-driven dissolution instability. If the characteristic length falls below a critical threshold, dissolution remains stable. Conversely, exceeding this threshold leads to two distinct regimes: the unstable regime of the confined domain affected by the initial aperture and the unstable regime of the semi-infinite domain independent of the initial aperture where the instability is no longer influenced by the lower boundary. We demonstrate that the pore-scale mechanism for this instability is due to the concentration boundary layer attaining a gravitationally unstable critical thickness. Through theoretical analysis of this layer and the time scales of diffusion and advection, we establish a theoretical model to predict where the dissolution instability occurs. This model aligns closely with our numerical simulations and experimental data across diverse conditions. Our work improves the understanding of buoyancy-driven dissolution instability in radial horizontal geometry. It is also of practical significance in understanding cavity formation in karst hydrology and preventing leaks in geological CO2 storage.
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Affiliation(s)
- Kai Li
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China
- Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education, Wuhan University, Wuhan 430072, China
| | - Ran Hu
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China
- Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education, Wuhan University, Wuhan 430072, China
| | - Ting Wang
- State Key Laboratory of Eco-Hydraulics in Northwest Arid Region of China, Xi'an University of Technology, Xi'an 710048, China
| | - Zhibing Yang
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China
- Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education, Wuhan University, Wuhan 430072, China
| | - Yi-Feng Chen
- State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, China
- Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering of the Ministry of Education, Wuhan University, Wuhan 430072, China
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2
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Baqer Y, Chen X. A review on reactive transport model and porosity evolution in the porous media. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:47873-47901. [PMID: 35522402 PMCID: PMC9252980 DOI: 10.1007/s11356-022-20466-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
This work comprehensively reviews the equations governing multicomponent flow and reactive transport in porous media on the pore-scale, mesoscale and continuum scale. For each of these approaches, the different numerical schemes for solving the coupled advection-diffusion-reactions equations are presented. The parameters influenced by coupled biological and chemical reactions in evolving porous media are emphasised and defined from a pore-scale perspective. Recent pore-scale studies, which have enhanced the basic understanding of processes that affect and control porous media parameters, are discussed. Subsequently, a summary of the common methods used to describe the transport process, fluid flow, reactive surface area and reaction parameters such as porosity, permeability and tortuosity are reviewed.
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Affiliation(s)
- Yousef Baqer
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK.
| | - Xiaohui Chen
- School of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK
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3
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Noiriel C, Soulaine C. Pore-Scale Imaging and Modelling of Reactive Flow in Evolving Porous Media: Tracking the Dynamics of the Fluid–Rock Interface. Transp Porous Media 2021. [DOI: 10.1007/s11242-021-01613-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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4
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Reactive Transport Simulation of Cavern Formation along Fractures in Carbonate Rocks. WATER 2020. [DOI: 10.3390/w13010038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Karst cavities and caves are often present along fractures in limestone reservoirs and are of significance for oil and gas exploration. Understanding the formation and evolution of caves in fractured carbonate rocks will enhance oil and gas exploration and development. Herein, a reactive transport model was established considering both the matrix and fractures. Different factors affecting the dissolution along fractures were considered in the simulation of matrix–fracture carbonate rocks, including the magnitude and characteristic length of the matrix porosity heterogeneity, intersecting fractures, and complex fracture network. The results show that a strong heterogeneity of the matrix porosity significantly affects the cave formation along the fracture and the existence of fractures increases the heterogeneity due to the high permeability as well as the dissolution area. The characteristic length of the matrix porosity heterogeneity affects the cave location and shape. The larger permeability of intersecting fractures or the matrix greatly increases the cave size, leading to the formation of large, connected cave areas. A complex fracture network leads to more developed karst dissolution caves. The topology of the fracture network and preferential flow dominate the distribution of caves and alleviate the effect of the matrix heterogeneity.
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5
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Deng H, Fitts JP, Tappero RV, Kim JJ, Peters CA. Acid Erosion of Carbonate Fractures and Accessibility of Arsenic-Bearing Minerals: In Operando Synchrotron-Based Microfluidic Experiment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:12502-12510. [PMID: 32845141 DOI: 10.1021/acs.est.0c03736] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Underground flows of acidic fluids through fractured rock can create new porosity and increase accessibility to hazardous trace elements such as arsenic. In this study, we developed a custom microfluidic cell for an in operando synchrotron experiment using X-ray attenuation. The experiment mimics reactive fracture flow by passing an acidic fluid over a surface of mineralogically heterogeneous rock from the Eagle Ford shale. Over 48 h, calcite was preferentially dissolved, forming an altered layer 200-500 μm thick with a porosity of 63-68% and surface area >10× higher than that in the unreacted shale as shown by xCT analyses. Calcite dissolution rate quantified from the attenuation data was 3 × 10-4 mol/m2s and decreased to 3 × 10-5 mol/m2s after 24 h because of increasing diffusion limitations. Erosion of the fracture surface increased access to iron-rich minerals, thereby increasing access to toxic metals such as arsenic. Quantification using XRF and XANES microspectroscopy indicated up to 0.5 wt % of As(-I) in arsenopyrite and 1.2 wt % of As(V) associated with ferrihydrite. This study provides valuable contributions for understanding and predicting fracture alteration and changes to the mobilization potential of hazardous metals and metalloids.
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Affiliation(s)
- Hang Deng
- Energy Geosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jeffrey P Fitts
- Columbia Electrochemical Energy Center, Columbia University, New York, New York 10027, United States
| | - Ryan V Tappero
- Photon Sciences Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Julie J Kim
- Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Catherine A Peters
- Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey 08544, United States
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6
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Fazeli H, Patel RA, Ellis BR, Hellevang H. Three-Dimensional Pore-Scale Modeling of Fracture Evolution in Heterogeneous Carbonate Caprock Subjected to CO 2-Enriched Brine. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:4630-4639. [PMID: 30945855 DOI: 10.1021/acs.est.8b05653] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Fractures in caprocks overlying CO2 storage reservoirs can adversely affect the sealing capacity of the rocks. Interactions between acidified fluid and minerals with different reactivities along a fracture pathway can affect the chemically induced changes in hydrodynamic properties of fractures. To study porosity and permeability evolution of small-scale (millimeter scale) fractures, a three-dimensional pore-scale reactive transport model based on the lattice Boltzmann method has been developed. The model simulates the evolution of two different fractured carbonate-rich caprock samples subjected to a flow of CO2-rich brine. The results show that the existence of nonreactive minerals along the flow path can restrict the increase in permeability and the cubic law used to relate porosity and permeability in monomineral fractured systems is therefore not valid in multimineral systems. Moreover, the injection of CO2-acidified brine at high rates resulted in a more permeable fractured media in comparison to the case with lower injection rates. The overall rate of calcite dissolution along the fracture decreased over time, confirming similar observations from previous continuum scale models. The presented 3D pore-scale model can be used to provide inputs for continuum scale models, such as improved porosity-permeability relationships for heterogeneous rocks, and also to investigate other reactive transport processes in the context of CO2 leakage in fractured seals.
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Affiliation(s)
- Hossein Fazeli
- Department of Geosciences , University of Oslo , Pb. 1047, Blindern, Oslo , Norway
| | - Ravi A Patel
- Laboratory for waste management (LES) , Paul Scherrer Institute , CH-5232 Villigen-PSI , Switzerland
| | - Brian R Ellis
- Department of Civil and Environmental Engineering , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Helge Hellevang
- Department of Geosciences , University of Oslo , Pb. 1047, Blindern, Oslo , Norway
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Molins S, Trebotich D, Arora B, Steefel CI, Deng H. Multi-scale Model of Reactive Transport in Fractured Media: Diffusion Limitations on Rates. Transp Porous Media 2019. [DOI: 10.1007/s11242-019-01266-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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8
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Deng H, Peters CA. Reactive Transport Simulation of Fracture Channelization and Transmissivity Evolution. ENVIRONMENTAL ENGINEERING SCIENCE 2019; 36:90-101. [PMID: 30713428 PMCID: PMC6354614 DOI: 10.1089/ees.2018.0244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 07/24/2018] [Indexed: 06/08/2023]
Abstract
Underground fractures serve as flow conduits, and they may produce unwanted migration of water and other fluids in the subsurface. An example is the migration and leakage of greenhouse gases in the context of geologic carbon sequestration. This study has generated new understanding about how acids erode carbonate fracture surfaces and the positive feedback between reaction and flow. A two-dimensional reactive transport model was developed and used to investigate the extent to which geochemical factors influence fracture permeability and transmissivity evolution in carbonate rocks. The only mineral modeled as reactive is calcite, a fast-reacting mineral that is abundant in subsurface formations. The X-ray computed tomography dataset from a previous experimental study of fractured cores exposed to carbonic acid served as a testbed to benchmark the model simulation results. The model was able to capture not only erosion of fracture surfaces but also the specific phenomenon of channelization, which produces accelerating transmissivity increase. Results corroborated experimental findings that higher reactivity of the influent solution leads to strong channelization without substantial mineral dissolution. Simulations using mineral maps of calcite in a specimen of Amherstburg limestone demonstrated that mineral heterogeneity can either facilitate or suppress the development of flow channels depending on the spatial patterns of reactive mineral. In these cases, fracture transmissivity may increase rapidly, increase slowly, or stay constant, and for all these possibilities, the calcite mineral continues to dissolve. Collectively, these results illustrate that fluid chemistry and mineral spatial patterns need to be considered in predictions of reaction-induced fracture alteration and risks of fluid migration.
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Affiliation(s)
- Hang Deng
- Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey
| | - Catherine A. Peters
- Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey
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9
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Spokas K, Peters CA, Pyrak-Nolte L. Influence of Rock Mineralogy on Reactive Fracture Evolution in Carbonate-Rich Caprocks. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:10144-10152. [PMID: 30091904 DOI: 10.1021/acs.est.8b01021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Fractures present environmental risks for subsurface engineering activities, such as geologic storage of greenhouse gases, because of the possibility of unwanted upward fluid migration. The risks of fluid leakage may be exacerbated if fractures are subjected to physical and chemical perturbations that alter their geometry. This study investigated this by constructing a 2D fracture model to numerically simulate fluid flow, acid-driven reactions, and mechanical deformation. Three rock mineralogies were simulated: a limestone with 100% calcite, a limestone with 68% calcite, and a banded shale with 34% calcite. One might expect transmissivity to increase fastest for rocks with more calcite due to its high solubility and fast reaction rate. Yet, results show that initially transmissivity increases fastest for rocks with less calcite because of their ability to deliver unbuffered-acid downstream faster. Moreover, less reactive minerals become persistent asperities that sustain mechanical support within the fracture. However, later in the simulations, the spatial pattern of less reactive mineral, not abundance, controls transmissivity evolution. Results show that a banded mineral pattern creates persistent bottlenecks, prevents channelization, and stabilizes transmissivity. For sites for geologic storage of CO2 that have carbonate caprocks, banded mineral variation may limit reactive evolution of fracture transmissivity and increase storage reliability.
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Affiliation(s)
- Kasparas Spokas
- Department of Civil & Environmental Engineering , Princeton University , Princeton , New Jersey 08544 , United States
| | - Catherine A Peters
- Department of Civil & Environmental Engineering , Princeton University , Princeton , New Jersey 08544 , United States
| | - Laura Pyrak-Nolte
- Department of Physics and Astronomy , Purdue University , West Lafayette , Indiana 47907 , United States
- Lyle School of Civil Engineering , Purdue University , West Lafayette , Indiana 47907 , United States
- Department of Earth, Atmospheric and Planetary Sciences , Purdue University , West Lafayette , Indiana 47907 , United States
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10
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Liu P, Yao J, Couples GD, Ma J, Iliev O. 3-D Modelling and Experimental Comparison of Reactive Flow in Carbonates under Radial Flow Conditions. Sci Rep 2017; 7:17711. [PMID: 29255165 PMCID: PMC5735102 DOI: 10.1038/s41598-017-18095-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 12/05/2017] [Indexed: 11/10/2022] Open
Abstract
We use a two-scale continuum model to simulate reactive flow and wormhole formation in carbonate rocks under 3-D radial flow conditions. More specifically, we present a new structure-property relationship based on the fractal geometry theory, to describe the evolution of local permeability, pore radius, and specific area with porosity variation. In the numerical calculation, to improve the convergence rate, the heterogeneous medium in question is extended by adding a thin layer of homogeneous porous medium to its inlet. We compare the simulation results with the available experimental observations and find that they are qualitatively consistent with each other. Additionally, sensitivity analysis of the dissolution process with respect to acid injection rate and rock heterogeneity, including heterogeneity magnitude and correlation length, is presented.
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Affiliation(s)
- Piyang Liu
- School of Petroleum Engineering, China University of Petroleum (East China), QingDao, 266580, China
| | - Jun Yao
- School of Petroleum Engineering, China University of Petroleum (East China), QingDao, 266580, China.
| | - Gary Douglas Couples
- Institute of Petroleum Engineering, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, UK
| | - Jingsheng Ma
- Institute of Petroleum Engineering, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, UK
| | - Oleg Iliev
- Fraunhofer Institute for Industrial Mathematics (ITWM), Kaiserslautern, 67663, Germany
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11
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Numerical modelling and analysis of reactive flow and wormhole formation in fractured carbonate rocks. Chem Eng Sci 2017. [DOI: 10.1016/j.ces.2017.06.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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12
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Qualitative and Quantitative Changes of Carbonate Rocks Exposed to SC CO2 (Basque-Cantabrian Basin, Northern Spain). APPLIED SCIENCES-BASEL 2017. [DOI: 10.3390/app7111124] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Menefee AH, Li P, Giammar DE, Ellis BR. Roles of Transport Limitations and Mineral Heterogeneity in Carbonation of Fractured Basalts. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:9352-9362. [PMID: 28700215 DOI: 10.1021/acs.est.7b00326] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Basalt formations could enable secure long-term carbon storage by trapping injected CO2 as stable carbonates. Here, a predictive modeling framework was designed to evaluate the roles of transport limitations and mineral spatial distributions on mineral dissolution and carbonation reactions in fractured basalts exposed to CO2-acidified fluids. Reactive transport models were developed in CrunchTope based on data from high-temperature, high-pressure flow-through experiments. Models isolating the effect of transport compared nine flow conditions under the same mineralogy. Heterogeneities were incorporated by segmenting an actual reacted basalt sample, and these results were compared to equivalent flow conditions through randomly generated mineral distributions with the same bulk composition. While pure advective flow with shorter retention times promotes rapid initial carbonation, pure diffusion sustains mineral reactions for longer time frames and generates greater net carbonate volumes. For the same transport conditions and bulk composition, exact mineral spatial distributions do not impact the amount of carbonation but could determine the location by controlling local solution saturation with respect to secondary carbonates. In combination, the results indicate that bulk mineralogy will be more significant than small-scale heterogeneities in controlling the rate and extent of CO2 mineralization, which will likely occur in diffusive zones adjacent to flow paths or in dead-end fractures.
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Affiliation(s)
- Anne H Menefee
- Department of Civil and Environmental Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Peiyuan Li
- Department of Civil and Environmental Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Daniel E Giammar
- Department of Energy, Environmental, and Chemical Engineering, Washington University , St. Louis, Missouri 63130, United States
| | - Brian R Ellis
- Department of Civil and Environmental Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
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Paukert Vankeuren AN, Hakala JA, Jarvis K, Moore JE. Mineral Reactions in Shale Gas Reservoirs: Barite Scale Formation from Reusing Produced Water As Hydraulic Fracturing Fluid. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:9391-9402. [PMID: 28723084 DOI: 10.1021/acs.est.7b01979] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Hydraulic fracturing for gas production is now ubiquitous in shale plays, but relatively little is known about shale-hydraulic fracturing fluid (HFF) reactions within the reservoir. To investigate reactions during the shut-in period of hydraulic fracturing, experiments were conducted flowing different HFFs through fractured Marcellus shale cores at reservoir temperature and pressure (66 °C, 20 MPa) for one week. Results indicate HFFs with hydrochloric acid cause substantial dissolution of carbonate minerals, as expected, increasing effective fracture volume (fracture volume + near-fracture matrix porosity) by 56-65%. HFFs with reused produced water composition cause precipitation of secondary minerals, particularly barite, decreasing effective fracture volume by 1-3%. Barite precipitation occurs despite the presence of antiscalants in experiments with and without shale contact and is driven in part by addition of dissolved sulfate from the decomposition of persulfate breakers in HFF at reservoir conditions. The overall effect of mineral changes on the reservoir has yet to be quantified, but the significant amount of barite scale formed by HFFs with reused produced water composition could reduce effective fracture volume. Further study is required to extrapolate experimental results to reservoir-scale and to explore the effect that mineral changes from HFF interaction with shale might have on gas production.
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Affiliation(s)
- Amelia N Paukert Vankeuren
- Geology Department, California State University Sacramento , Sacramento, California 95819, United States
- National Energy Technology Laboratory, U.S. Department of Energy , Pittsburgh, Pennsylvania 15236, United States
| | - J Alexandra Hakala
- National Energy Technology Laboratory, U.S. Department of Energy , Pittsburgh, Pennsylvania 15236, United States
| | - Karl Jarvis
- National Energy Technology Laboratory, U.S. Department of Energy , Morgantown, West Virginia 26507, United States
- AECOM , Morgantown, West Virginia 26507, United States
| | - Johnathan E Moore
- National Energy Technology Laboratory, U.S. Department of Energy , Morgantown, West Virginia 26507, United States
- AECOM , Morgantown, West Virginia 26507, United States
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15
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Deng H, Voltolini M, Molins S, Steefel C, DePaolo D, Ajo-Franklin J, Yang L. Alteration and Erosion of Rock Matrix Bordering a Carbonate-Rich Shale Fracture. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:8861-8868. [PMID: 28682076 DOI: 10.1021/acs.est.7b02063] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A novel reactive transport model has been developed to examine the processes that affect fracture evolution in a carbonate-rich shale. An in situ synchrotron X-ray microtomography experiment, flowing CO2 saturated water through a single fracture mini-core of Niobrara Shale provided the experimental observations for the development and testing of the model. The phenomena observed included the development of a porous altered layer, flow channeling, and increasingly limited calcite dissolution. The experimental observations cannot be explained by models that consider only mineral dissolution and development of an altered layer. The difference between the fracture volume change recorded by the microtomography images and what would be expected from mineral dissolution alone suggest that there is erosion of the altered layer as it develops. The numerical model includes this additional mechanism, with the erosion rate based on the thickness of the altered layer, and successfully captures the evolution of the geochemical reactions and morphology of the fracture. The findings imply that the abundance (with a threshold of approximately 35%) and reactivity of the rapidly reacting mineral control the development and erodibility of the altered layer on the fracture surfaces, and therefore fracture opening.
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Affiliation(s)
- Hang Deng
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Marco Voltolini
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Sergi Molins
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Carl Steefel
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Donald DePaolo
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Earth and Planetary Science, University of California, Berkeley , Berkeley, California 94720, United States
| | | | - Li Yang
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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16
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Noiriel C, Daval D. Pore-Scale Geochemical Reactivity Associated with CO 2 Storage: New Frontiers at the Fluid-Solid Interface. Acc Chem Res 2017; 50:759-768. [PMID: 28362082 DOI: 10.1021/acs.accounts.7b00019] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The reactivity of carbonate and silicate minerals is at the heart of porosity and pore geometry changes in rocks injected with CO2, which ultimately control the evolution of flow and transport properties of fluids in porous and/or fractured geological reservoirs. Modeling the dynamics of CO2-water-rock interactions is challenging because of the resulting large geochemical disequilibrium, the reservoir heterogeneities, and the large space and time scales involved in the processes. In particular, there is a lack of information about how the macroscopic properties of a reservoir, e.g., the permeability, will evolve as a result of geochemical reactions at the molecular scale. Addressing this point requires a fundamental understanding of how the microstructures influence the macroscopic properties of rocks. The pore scale, which ranges from a few nanometers to centimeters, has stood out as an essential scale of observation of geochemical processes in rocks. Transport or surface reactivity limitations due to the pore space architecture, for instance, are best described at the pore scale itself. It can be also considered as a mesoscale for aggregating and increasing the gain of fundamental understanding of microscopic interfacial processes. Here we focus on the potential application of a combination of physicochemical measurements coupled with nanoscale and microscale imaging techniques during laboratory experiments to improve our understanding of the physicochemical mechanisms that occur at the fluid-solid interface and the dynamics of the coupling between the geochemical reactions and flow and transport modifications at the pore scale. Imaging techniques such as atomic force microscopy, vertical scanning interferometry, focused ion beam transmission electron microscopy, and X-ray microtomography, are ideal for investigating the reactivity dynamics of these complex materials. Minerals and mineral assemblages, i.e., rocks, exhibit heterogeneous and anisotropic reactivity, which challenges the continuum description of porous media and assumptions required for reactive transport modeling at larger scales. The conventional approach, which consists of developing dissolution rate laws normalized to the surface area, should be revisited to account for both the anisotropic crystallographic structure of minerals and the transport of chemical species near the interface, which are responsible for the intrinsic evolution of the mineral dissolution rate as the reaction progresses. In addition, the crystal morphology and the mineral assemblage composition, texture, and structural heterogeneities are crucial in determining whether the permeability and transport properties of the reservoir will be altered drastically or maintain the sealing properties required to ensure the safe sequestration of CO2 for hundreds of years. Investigating the transport properties in nanometer- to micrometer-thick amorphous Si-rich surface layers (ASSLs), which develop at the fluid-mineral interface in silicates, provides future direction, as ASSLs may prevent contact between the dissolving solids and the pore fluid, potentially inhibiting the dissolution/carbonation process. Equally, at a larger scale, the growth of micrometer- to millimeter-thick alteration layers, which result from the difference in reactivity between silicates and carbonates, slows the transport in the vicinity of the fluid-solid interface in polymineralic rocks, thus limiting the global reactivity of the carbonate matrix. In contrast, in pure limestone, the global reactivity of the monomineralic rock decreases because the flow localization promotes the local reactivity within the forming channels, thus enhancing permeability changes compared with more homogeneous dissolution of the rock matrix. These results indicate that the transformation of the rock matrix should control the evolution of the transport properties in reservoirs injected with CO2 to the same extent as the intrinsic chemical reactivity of the minerals and the reservoir hydrodynamics. This process, which is currently not captured by large-scale modeling of reactive transport, should benefit from the increasing capabilities of noninvasive and nondestructive characterization tools for pore-scale processes, ultimately constraining reactive transport modeling and improving the reliability of predictions.
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Affiliation(s)
- Catherine Noiriel
- Géosciences
Environnement Toulouse, Observatoire Midi-Pyrénées, Université Paul Sabatier, CNRS, IRD, 14 avenue Edouard Belin, F-31400 Toulouse, France
| | - Damien Daval
- Laboratoire
d’Hydrologie et de Géochimie de Strasbourg, Université de Strasbourg, EOST, CNRS, 67084 Strasbourg, France
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17
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Al-Khulaifi Y, Lin Q, Blunt MJ, Bijeljic B. Reaction Rates in Chemically Heterogeneous Rock: Coupled Impact of Structure and Flow Properties Studied by X-ray Microtomography. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:4108-4116. [PMID: 28287717 DOI: 10.1021/acs.est.6b06224] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We study dissolution in a chemically heterogeneous medium consisting of two minerals with contrasting initial structure and transport properties. We perform a reactive transport experiment using CO2-saturated brine at reservoir conditions in a millimeter-scale composite core composed of Silurian dolomite and Ketton limestone (calcite) arranged in series. We repeatedly image the composite core using X-ray microtomography (XMT) and collect effluent to assess the individual mineral dissolution. The mineral dissolution from image analysis was comparable to that measured from effluent analysis using inductively coupled plasma mass spectrometry (ICP-MS). We find that the ratio of the effective reaction rate of calcite to that of dolomite decreases with time, indicating the influence of dynamic transport effects originating from changes in pore structure coupled with differences in intrinsic reaction rates. Moreover, evolving flow and transport heterogeneity in the initially heterogeneous dolomite is a key determinant in producing a two-stage dissolution in the calcite. The first stage is characterized by a uniform dissolution of the pore space, while the second stage follows a single-channel growth regime. This implies that spatial memory effects in the medium with a heterogeneous flow characteristic (dolomite) can change the dissolution patterns in the medium with a homogeneous flow characteristic (calcite).
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Affiliation(s)
- Yousef Al-Khulaifi
- Department of Earth Science and Engineering and ‡Qatar Carbonates and Carbon Storage Research Centre, Department of Earth Science and Engineering, Imperial College London , London SW7 2AZ, United Kingdom
| | - Qingyang Lin
- Department of Earth Science and Engineering and ‡Qatar Carbonates and Carbon Storage Research Centre, Department of Earth Science and Engineering, Imperial College London , London SW7 2AZ, United Kingdom
| | - Martin J Blunt
- Department of Earth Science and Engineering and ‡Qatar Carbonates and Carbon Storage Research Centre, Department of Earth Science and Engineering, Imperial College London , London SW7 2AZ, United Kingdom
| | - Branko Bijeljic
- Department of Earth Science and Engineering and ‡Qatar Carbonates and Carbon Storage Research Centre, Department of Earth Science and Engineering, Imperial College London , London SW7 2AZ, United Kingdom
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