Propagation of Cryogenic Thermal Fractures from Unconfined PMMA Boreholes
In cryogenic fracturing, a rock surface exposed to cryogenic fluids undergoes a large thermal gradient, and the resultant local tensile stress overcomes rock strength and initiates fractures. This study investigates the development of cracks generated from the cryogenic treatment of a borehole under...
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MDPI AG
2021-09-01
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| Online Access: | https://www.mdpi.com/1996-1073/14/17/5433 |
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| author | Minsu Cha Naif B. Alqahtani Xiaolong Yin Lei Wang Bowen Yao Timothy J. Kneafsey Jennifer L. Miskimins Yu-Shu Wu |
| author_facet | Minsu Cha Naif B. Alqahtani Xiaolong Yin Lei Wang Bowen Yao Timothy J. Kneafsey Jennifer L. Miskimins Yu-Shu Wu |
| author_sort | Minsu Cha |
| collection | DOAJ |
| description | In cryogenic fracturing, a rock surface exposed to cryogenic fluids undergoes a large thermal gradient, and the resultant local tensile stress overcomes rock strength and initiates fractures. This study investigates the development of cracks generated from the cryogenic treatment of a borehole under no external confining stress on specimens. The experiments were performed on transparent PMMA specimens to observe fracture proliferation around boreholes. Liquid nitrogen was flowed through the boreholes to cool the borehole surface. The results show that initial fracture growth is characterized by abrupt starts and stops, and as the fracture propagates outward, the growth appears more continuous. In an early stage, horizontal/radial fractures and vertical fractures are the defining patterns. Horizontal fractures tend to be separated by a specific exclusion distance (i.e., spacing between cracks). While distinct horizontal/vertical fractures and exclusion distance manifest themselves at an early stage, fractures resulting from fracture interactions and curvatures can develop into complex shapes at later stages. Cryogenic thermal loading induces distinctively curved fractures. The tendency of curvature may prevent greater penetration. An increase in the borehole pressure during liquid nitrogen flow, however, can lessen fracture tortuosity and facilitate radial propagation. A high flow pressure and rate are also advantageous in that they accelerate cooling and fracture propagation. |
| first_indexed | 2024-03-10T08:12:56Z |
| format | Article |
| id | doaj.art-abf22abb926748e29b81f34faee7f212 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-10T08:12:56Z |
| publishDate | 2021-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-abf22abb926748e29b81f34faee7f2122023-11-22T10:34:36ZengMDPI AGEnergies1996-10732021-09-011417543310.3390/en14175433Propagation of Cryogenic Thermal Fractures from Unconfined PMMA BoreholesMinsu Cha0Naif B. Alqahtani1Xiaolong Yin2Lei Wang3Bowen Yao4Timothy J. Kneafsey5Jennifer L. Miskimins6Yu-Shu Wu7Department of Civil Engineering, Jeju National University, Jeju-si 63243, KoreaCarbon Capture, Utilization, and Storage Research Center, King Abdulaziz City for Science and Technology (KACST), Riyadh 11442, Saudi ArabiaDepartment of Petroleum Engineering, Colorado School of Mines, 1600 Arapahoe St., Golden, CO 80401, USASchool of Mining & Geosciences, Nazarbayev University, Qabanbay Batyr Ave 53, Nur-Sultan City 010000, KazakhstanDepartment of Petroleum Engineering, Colorado School of Mines, 1600 Arapahoe St., Golden, CO 80401, USAHydrocarbon Resources Program, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USADepartment of Petroleum Engineering, Colorado School of Mines, 1600 Arapahoe St., Golden, CO 80401, USADepartment of Petroleum Engineering, Colorado School of Mines, 1600 Arapahoe St., Golden, CO 80401, USAIn cryogenic fracturing, a rock surface exposed to cryogenic fluids undergoes a large thermal gradient, and the resultant local tensile stress overcomes rock strength and initiates fractures. This study investigates the development of cracks generated from the cryogenic treatment of a borehole under no external confining stress on specimens. The experiments were performed on transparent PMMA specimens to observe fracture proliferation around boreholes. Liquid nitrogen was flowed through the boreholes to cool the borehole surface. The results show that initial fracture growth is characterized by abrupt starts and stops, and as the fracture propagates outward, the growth appears more continuous. In an early stage, horizontal/radial fractures and vertical fractures are the defining patterns. Horizontal fractures tend to be separated by a specific exclusion distance (i.e., spacing between cracks). While distinct horizontal/vertical fractures and exclusion distance manifest themselves at an early stage, fractures resulting from fracture interactions and curvatures can develop into complex shapes at later stages. Cryogenic thermal loading induces distinctively curved fractures. The tendency of curvature may prevent greater penetration. An increase in the borehole pressure during liquid nitrogen flow, however, can lessen fracture tortuosity and facilitate radial propagation. A high flow pressure and rate are also advantageous in that they accelerate cooling and fracture propagation.https://www.mdpi.com/1996-1073/14/17/5433cryogenic fracturingthermal fracturesliquid nitrogenthermal shockthermal stresshydraulic fracturing |
| spellingShingle | Minsu Cha Naif B. Alqahtani Xiaolong Yin Lei Wang Bowen Yao Timothy J. Kneafsey Jennifer L. Miskimins Yu-Shu Wu Propagation of Cryogenic Thermal Fractures from Unconfined PMMA Boreholes Energies cryogenic fracturing thermal fractures liquid nitrogen thermal shock thermal stress hydraulic fracturing |
| title | Propagation of Cryogenic Thermal Fractures from Unconfined PMMA Boreholes |
| title_full | Propagation of Cryogenic Thermal Fractures from Unconfined PMMA Boreholes |
| title_fullStr | Propagation of Cryogenic Thermal Fractures from Unconfined PMMA Boreholes |
| title_full_unstemmed | Propagation of Cryogenic Thermal Fractures from Unconfined PMMA Boreholes |
| title_short | Propagation of Cryogenic Thermal Fractures from Unconfined PMMA Boreholes |
| title_sort | propagation of cryogenic thermal fractures from unconfined pmma boreholes |
| topic | cryogenic fracturing thermal fractures liquid nitrogen thermal shock thermal stress hydraulic fracturing |
| url | https://www.mdpi.com/1996-1073/14/17/5433 |
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