Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures
We report experimental observations of permeation of CO2-rich aqueous fluids of varied acidic potential (pH) on three different shales to investigate mechanical, chemical, and mineralogical effects on fracture permeability evolution. Surface profilometry and SEM-EDS (scanning electron microscopy wit...
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| Format: | Article |
| Language: | English |
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Wiley
2018-01-01
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| Series: | Geofluids |
| Online Access: | http://dx.doi.org/10.1155/2018/7801843 |
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| author | Yunzhong Jia Yiyu Lu Jiren Tang Yi Fang Binwei Xia Zhaolong Ge |
| author_facet | Yunzhong Jia Yiyu Lu Jiren Tang Yi Fang Binwei Xia Zhaolong Ge |
| author_sort | Yunzhong Jia |
| collection | DOAJ |
| description | We report experimental observations of permeation of CO2-rich aqueous fluids of varied acidic potential (pH) on three different shales to investigate mechanical, chemical, and mineralogical effects on fracture permeability evolution. Surface profilometry and SEM-EDS (scanning electron microscopy with energy-dispersive X-ray spectroscopy) methods are employed to quantify the evolution in both roughness on and chemical constituents within the fracture surface. Results indicate that, after 12 hours of fluid flow, fracture effective hydraulic apertures evolve distinctly under different combinations of shale mineralogy, effective stress, and fluid acidity. The evolution of roughness and transformation of chemical elements on the fracture surface are in accordance with the evolution of permeability. The experimental observations imply that (1) CO2-rich aqueous fluids have significant impact on the evolution of fracture permeability and may influence (and increase) shale gas production; (2) shale mineralogy, especially calcite mineral, decides the chemical reaction and permeability increasing when CO2-rich aqueous fluids flow through fractures by free-face dissolution effect; (3) clay mineral swelling reduces fracture aperture and additively calcite pressure solution removes the bridging asperities, which are the main reasons for fracture permeability decrease; (4) competition roles among clay mineral swelling, mineral pressure solution, and free-face dissolution determine how fracture permeability changes. Furthermore, a multiple parameter model is built to analyze effective hydraulic aperture evolution in considering above three mechanisms, which provide a reference to forecast fracture permeability evolution in shale formations. |
| format | Article |
| id | doaj-art-cb69e52563f64f3d976719aa98cce3ad |
| institution | Kabale University |
| issn | 1468-8115 1468-8123 |
| language | English |
| publishDate | 2018-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geofluids |
| spelling | doaj-art-cb69e52563f64f3d976719aa98cce3ad2025-02-03T05:48:26ZengWileyGeofluids1468-81151468-81232018-01-01201810.1155/2018/78018437801843Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale FracturesYunzhong Jia0Yiyu Lu1Jiren Tang2Yi Fang3Binwei Xia4Zhaolong Ge5State Key Laboratory for Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, ChinaState Key Laboratory for Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, ChinaState Key Laboratory for Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, ChinaDepartment of Energy and Mineral Engineering, EMS Energy Institute, and G3 Center, The Pennsylvania State University, University Park, PA 16802, USAState Key Laboratory for Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, ChinaState Key Laboratory for Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, ChinaWe report experimental observations of permeation of CO2-rich aqueous fluids of varied acidic potential (pH) on three different shales to investigate mechanical, chemical, and mineralogical effects on fracture permeability evolution. Surface profilometry and SEM-EDS (scanning electron microscopy with energy-dispersive X-ray spectroscopy) methods are employed to quantify the evolution in both roughness on and chemical constituents within the fracture surface. Results indicate that, after 12 hours of fluid flow, fracture effective hydraulic apertures evolve distinctly under different combinations of shale mineralogy, effective stress, and fluid acidity. The evolution of roughness and transformation of chemical elements on the fracture surface are in accordance with the evolution of permeability. The experimental observations imply that (1) CO2-rich aqueous fluids have significant impact on the evolution of fracture permeability and may influence (and increase) shale gas production; (2) shale mineralogy, especially calcite mineral, decides the chemical reaction and permeability increasing when CO2-rich aqueous fluids flow through fractures by free-face dissolution effect; (3) clay mineral swelling reduces fracture aperture and additively calcite pressure solution removes the bridging asperities, which are the main reasons for fracture permeability decrease; (4) competition roles among clay mineral swelling, mineral pressure solution, and free-face dissolution determine how fracture permeability changes. Furthermore, a multiple parameter model is built to analyze effective hydraulic aperture evolution in considering above three mechanisms, which provide a reference to forecast fracture permeability evolution in shale formations.http://dx.doi.org/10.1155/2018/7801843 |
| spellingShingle | Yunzhong Jia Yiyu Lu Jiren Tang Yi Fang Binwei Xia Zhaolong Ge Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures Geofluids |
| title | Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures |
| title_full | Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures |
| title_fullStr | Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures |
| title_full_unstemmed | Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures |
| title_short | Mechanical-Chemical-Mineralogical Controls on Permeability Evolution of Shale Fractures |
| title_sort | mechanical chemical mineralogical controls on permeability evolution of shale fractures |
| url | http://dx.doi.org/10.1155/2018/7801843 |
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