Microwave stimulation for enhanced shale gas recovery
| Main Authors: | Chen,Tianyu, Feng,Xiating, Zheng,Xu, Qiu,Xin, Elsworth, Derek, Cui,Guanglei, Jia,Zhanhe, Pan,Zhejun |
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| Format: | Article |
| Bahasa: | eng |
| Terbitan: |
, 2020
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/3665295 |
Daftar Isi:
- Microwave fracturing is a potentially green stimulation technology for gas shale recovery. Fracturing mechanisms and the evolution of permeability in the treated reservoir remain unclear. We explore the response of Longmaxi shale (Sichuan basin, southwest China) to both continuous and intermittent microwave stimulation along variable microwave heating paths. Evolution of the petrophysical parameters of the shale including wave velocity, mass and volume at different intermittent microwave radiation steps were measured together with temperature. The evolution of permeability for two shale sample with alternately parallel bedding and vertical bedding at different effective stresses was analysed both before and after microwave radiation. Evolving pore size was measured by high-pressure mercury porosimetry and thermal-induced fracture characteristics and the changes of mineral composition were characterized by SEM combined with EDS. A permeability model with variable compressibility was used to fit the experimental data for shale permeability across a wide range of effective stresses from 2.5 MPa to 59.5 MPa. The effects of microwave heating on compressibility and permeability anisotropy show that a complex heating-induced fracture network results under the intermittent microwave radiation. Thermally- and chemically-induced (swelling) stresses are mainly responsible for the development of fractures and micro-porosity in the shale. After the last step of intermittent microwave irradiation, the shale permeability increased by two to four orders of magnitude. Microwave treatment accentuates the anisotropy between bedding-parallel and bedding-normal permeabilities. Shale compressibility decreases in the later stage of microwave irradiation, suggesting the hardening of thermal-induced fractures.