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Abstract Tri-axial hydraulic fracturing experiments using supercritical Co2 (SC- Co2), water and viscous oil have been conducted in order to investigate how the viscosity of fracturing fluid affects fracture propagation and fracture mode. We performed these experiments on cubic granite specimens and monitored acoustic emission (AE) with 16 sensors. AE data analysis allows us to clarify fracture propagation and its mode. The effects of fluid viscosity on the distribution of AE sources and the fracture mode are discussed. Macroscopic observations of the surface fractures were consistent with located AE sources. The distribution of AE sources indicated that fracturing with low viscosity fluid such as SC- Co2 can induce more widely and complexly extending fractures than those with higher viscosity fluid like water and oil. In addition, the analysis of the fracture mechanism showed that low viscosity fluid such as SC- Co2 induces shear dominant fracture, while high viscosity fluid induces tensile dominant fracture. Thus, since Co2 has a higher affinity to shale than methane and enhances methane desorption, Co2 fracturing could be an effective technique particularly for shale gas recovery.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Igneous Rock > Granite (0.62)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.47)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)
Fracture Development and Mechanism in Shale Cores by Viscous Oil, Water and L- Co2 Injection
Bennour, Z. (Kyoto University) | Ishida, T. (Kyoto University) | Nagaya, Y. (Kyoto University) | Nara, Y. (Kyoto University) | Chen, Y. (Kyoto University) | Chen, Q. (3D Geoscience Inc.) | Nakayama, Y. (3D Geoscience Inc.) | Sekine, K. (JOGMEC) | Nagano, Y. (JOGMEC)
Abstract Hydraulic fracturing experiments were run on cylindrical cores from a shale stratum at a coal mine in Japan. Experiments were made under two uniaxial stresses 0 and 3 MPa and by using three types of fluids: viscous oil, water and liquid carbon dioxide (L- Co2). As for results, from the crack observation and AE source distribution, in the experiments used water and oil as fracturing fluid, fractures extend along the sedimentary plane if tests were run without loading, while they extend along the loading direction normal to the sedimentary plane under the uniaxial loading. These results suggest that the direction of crack extension is strongly affected by in-situ stress condition. However, the L- Co2 fracturing didn’t show this tendency, this might be related to the low viscosity of L- Co2. From the analysis of the ratio of polarity of P-wave initial motions, it was found that viscous oil injection tends to induce Mode-I fracture while both water and L- Co2 injection tend to induce Mode-II fracture.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.89)
- Reservoir Description and Dynamics > Storage Reservoir Engineering > CO2 capture and sequestration (0.88)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (0.88)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (0.71)
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