| Citation: |
Hua Xue, Min Du, Bin Zhao, Bao-jin Zhang, Sheng-xuan Liu, Peng-fei Wen, Bin Liu, Ru-wei Zhang, Yun-xia Xu, Xi Chen, 2020. Seismic fine imaging and its significance for natural gas hydrate exploration in the Shenhu Test Area, South China Sea, China Geology, 3, 524-532. doi: 10.31035/cg2020037
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Seismic fine imaging and its significance for natural gas hydrate exploration in the Shenhu Test Area, South China Sea
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Abstract
Shenhu area in South China Sea includes extensive collapse and diapir structures, forming high-angle faults and vertical fracture system, which functions as a fluid migration channel for gas hydrate formation. In order to improve the imaging precision of natural gas hydrate in this area, especially for fault and fracture structures, the present work propose a velocity stitching technique that accelerates effectively the convergence of the shallow seafloor, indicating seafloor horizon interpretation and the initial interval velocity for model building. In the depth domain, pre-stack depth migration and residual curvature are built into the model based on high-precision grid-tomography velocity inversion, after several rounds of tomographic iterations, as the residual velocity field converges gradually. Test results of the Shenhu area show that the imaging precision of the fault zone is obviously improved, the fracture structures appear more clearly, the wave group characteristics significantly change for the better and the signal-to-noise ratio and resolution are improved. These improvements provide the necessary basis for the new reservoir model and field drilling risk tips, help optimize the favorable drilling target, and are crucial for the natural gas resource potential evaluation.
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References
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Hua Xue, Min Du, Bin Zhao, Bao-jin Zhang, Sheng-xuan Liu, Peng-fei Wen, Bin Liu, Ru-wei Zhang, Yun-xia Xu, Xi Chen, 2020. Seismic fine imaging and its significance for natural gas hydrate exploration in the Shenhu Test Area, South China Sea, China Geology, 3, 524-532. doi: 10.31035/cg2020037
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Figure 1.
Location maps of the Shenhu area.
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Figure 2.
Initial velocity model establishment using velocity splicing of line 2947.
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Figure 3.
The overlapped display of residual curvature and residual velocity spectrum of line 3100.
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Figure 4.
Residual curvature profile with different resolutions of line 3100.
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Figure 5.
Seed points distribution with pre-stack profile of line 3100.
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Figure 6.
The overlapped display of the residual velocity field with the pre-stack gathers of line 3100.
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Figure 7.
The overlapped display of the structure attribute field with pre-stack profile automatically picked up along different directions of line 3100.
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Figure 8.
The final interval velocity profile after tomography inversion of line 2846.
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Figure 9.
Overlap display of after tomography the final interval velocity profile, PSDM profile, fault and vertical fracture system of line 2864.