Geophysical Signature of the Shallow Water Flow in the Deepwater Basin of the Northern South China Sea
Tóm tắt
Shallow water flow (SWF), a disastrous geohazard in the continental margin, has threatened deepwater drilling operations. Under overpressure conditions, continual flow delivering unconsolidated sands upward in the shallow layer below the seafloor may cause large and long-lasting uncontrolled flows; these flows may lead to control problems and cause well damage and foundation failure. Eruptions from over-pressured sands may result in seafloor craters, mounds, and cracks. Detailed studies of 2D/3D seismic data from a slope basin of the South China Sea (SCS) indicated the potential presence of SWF. It is commonly characterized by lower elastic impedance, a higher Vp/Vs ratio, and a higher Poisson’s ratio than that for the surrounding sediments. Analysis of geological data indicated the SWF zone originated from a deepwater channel system with gas bearing over-pressured fluid flow and a high sedimentation rate. We proposed a fluid flow model for SWF that clearly identifies its stress and pressure changes. The rupture of previous SWF zones caused the fluid flow that occurred in the Baiyun Sag of the northern SCS.
Tài liệu tham khảo
Alberty, M. W., Hafle, M. E., and Minge, J. C., 1999. Mechanisms of shallow waterflows and drilling practices for intervention. SPE Drilling and Completion, 14 (2): 123–129.
Bowers, G. L., 1995. Pore pressure estimation from velocity data: Accounting for pore pressure mechanisms besides undercompaction. SPE Drilling and Completion, 10 (2): 89–95.
Bruce, B., 2002. Pore pressure terminology. The Leading Edge, 21 (2): 170–173.
Dong, D. D., Wu, S. G., Zhang, G. C., and Yuan, S. Q., 2008. Rifting process and formation mechanisms of syn-rift stage prolongation in the deepwater basin, northern South China Sea. Chinese Science Bulletin, 53 (23): 3715–3725.
Dugan, B., and Flemings, P. B., 2002. Fluid flow and stability of the US continental slope offshore New Jersey from the Pleistocene to present. Geofluids, 2 (2): 137–146.
Dugan, B., Flemings, P. B., David, L. O., and Gooch, M. J., 2003. Consolidation, effective stress, and fluid pressure of sediments from ODP Site 1073, US mid-Atlantic continental slope. Earth and Planetary Science Letters, 215 (1): 13–26.
Dutta, N. C., 2002. Geopressure prediction using seismic data: Current status and the road ahead. Geophysics, 67 (6): 2012–2041.
Dutta, N. C., and Ray, A., 1997. Image of geopressured rocks using velocity and acoustic impedance inversion of seismic data. SEG Annual Meeting, Dallas, Texas, 1929.
Gardner, G. H. F., Gardner, L. W., and Gregory, A. R., 1974. Formation velocity and density–The diagnostic basics for stratigraphic traps. Geophysics, 39 (6): 770–780.
Gene, S., 2002. Introduction–Shallow or deep, which is it? The Leading Edge, 21 (7): 659.
Gong, Z. S., Li, S. T., and Xie, T., 1997. Continental Margin Basin Analysis and Hydrocarbon Accumulation in the Northern South China Sea. Science Press, Beijing, 193–256.
Hardage, B. A., Remington, R., and Roberts, H. H., 2006. Gas hydrate–A source of shallow water flow? The Leading Edge, 25 (5): 634–635.
He, M., Zhu, M., Wang, R. L., Lian, S. Y., and Wu, X. J., 2007. The discussion of time-depth conversion methods in the Baiyun deepwater routgh seafloor area. Progress in Geophysics, 22 (3): 966–971 (in Chinese with English abstract).
Heggland, R., 2004. Definition of geohazards in exploration 3-d seismic data using attributes and neural-network analysis. AAPG Bulletin, 88 (6): 857–868.
Huffman, A. R., and Castagna, J. P., 2001. The petrophysical basis for shallow-water flow prediction using multicomponent seismic data. The Leading Edge, 20 (9): 1030–1052.
Kok, R. D., Dutta, N., Khan, M., and Mallick, S., 2001. Deepwater geohazard analysis using prestack inversion. SEG Annual Meeting, San Antonio, USA, 0613.
Li, S. T., Lin, C. S., and Zhang, Q. M., 1998. Dynamic process of episodic rifting in continental maginal basin and tectonic events since 10 Ma in the SCS. Chinese Sciences Bulletin, 43 (8): 797–810.
Liu, Z. F., Colin, C., Huang, W., and Trentesaux, A., 2008. Clay minerals in surface sediments of the Pearl River drainage basin and their contribution to the South China Sea. Chinese Science Bulletin, 52 (8): 1101–1111.
Liu, Z. F., Trentesaux, A., Clemens, S. C., and Wang, P. X., 2003. Quaternary clay mineralogy in the northern South China Sea (ODP Site 1146)–Implications for oceanic current transport and East Asian monsoon evolution. Science in China (Series D), 46 (12): 1123–1135.
Lv, S. M., 2003. Seismic characteristic of two deep-water drilling hazards: Shallow-water flow sands and gas hydrate. PhD thesis. University of Texas, Dallas.
Lv, S. M., McMechan, G. A., and Liaw, A., 2005. Identification of shallow water flow sands by Vp/Vs inversion of conventional 3D seismic data. Geophysics, 70 (5): 29–37.
Lüdmann, T., and Wong, H. K., 1999. Neotectonic regime on the passive continental margin of the South China Sea. Tectonophysics, 311 (1-4): 113–138.
Lüdmann, T., Wong, H. K., and Wang, P. X., 2001. Plio-Quaternary sedimentation processes and neotectonics of the northern continental margin of the South China Sea. Marine Geology, 172 (3-4): 331–358.
Mallick, S., 1995. Model-based inversion of amplitude-variation with offset data using a genetic algorithm. Geophysics, 60 (4): 939–954.
Mallick, S., 1999. Some practical aspects of prestack waveform inversion using a genetic algorithm: An example from the east Texas Woodbine gas sand. Geophysics, 64 (2): 326–336.
Mallick, S., and Dutta, N. C., 2002. Shallow water flow prediction using prestack waveform inversion of conventional 3D seismic data and rock modeling. The Leading Edge, 21 (7): 675–680.
Mallick, S., Huang, X., Jeffrey, L., and Ahmad, R., 2000. Hybrid seismic inversion: A reconnaissance tool for deepwater exploration. The Leading Edge, 19 (11): 1230–1237.
McConnell, D. R., 2000. Optimizing deepwater well locations to reduce the risk of shallow water flow using high resolution 2D and 3D seismic data. Proceedings of Offshore Technology Conference, Houston, Texas, OTC11973.
Mukerji, T., Dutta, N., Prasad, M., and Dvorkin, J., 2002. Seismic detection and estimation of overpressures Part I: The rock physics basis. CSEG Recorder, 27 (7): 34–57.
Ostermeier, R. M., Pelletieh, J. H., Winker, C. D., Nicholson, J. W., Rambow, F. H., and Cowan, K. M., 2000. Dealing with shallow-water flow in the deepwater Gulf of Mexico. The Leading Edge, 21 (7): 660–668.
Pang, X., Chen, C. M., Wu, M. S., He, M., and Wu, X. J., 2006. The Pearl River deep-water fan systems and significant geological events. Advances in Earth Science, 21 (8): 793–799.
Peng, D. J., Pang, X., Chen, C. M., Zhu, M., Huang, X. L., and Shu, Y., 2006. The characteristics and controlling factors for the formation of deep-water fan system in South China Sea. Acta Sedimentologica Sinica, 24 (1): 10–18 (in Chinese with English abstract).
Prasad, M., 2002. Acoustic measurements in unconsolidated sands at low effective pressure and overpressure detection. Geophysics, 67 (2): 405–412.
Qin, G. Q., 2002. Late Cenozoic sequence stratigraphy and sealevel changes in Pearl River Mouth Basin, South China Sea. China Offshore Oil and Gas (Geology), 16 (1): 1–10 (in Chinese with English abstract).
Rocha, L. S., Junqueira, P., and Roque, J., 2003. Overcoming deep and ultra deepwater drilling challenges. Offshore Technology Conference, Houston, Texas, 1–12.
Sun, Q., Alves, T., Xie, X., He, J., Li, W., and Ni, X., 2017. Free gas accumulations in basal shear zones of mass-transport deposits (Pearl River Mouth Basin, South China Sea): An important geohazard on continental slope basins. Marine and Petroleum Geology, 81: 17–32.
Sun, Z., Pang, X., Zhong, Z. H., Zhou, D., Chen, C. M., Hao, H. J., Huang, C. J., and Xu, H. H., 2005. Dynamics of tertiary tectonic evolution of the Baiyun Sag in the Pearl River Mouth Basin. Earth Science Frontiers, 12 (4): 489–498 (in Chinese with English abstract).
Taylor, B., and Hayes, D. E., 1983. Origin and history of the South China Sea. In: The Tectonic and Geologic Evolution of Southeast Asian Seas and Islands, Part 2, Geophysical Monography Series. Hayes, D. E., ed., American Geophysical Union, Washington, D. C., 23–56.
Wang, X. J., Lee, M., Collett, T., Yang, S. X., Guo, Y. Q., and Wu, S. G., 2014. Gas hydrate identified in sand-rich inferred sedimentary section using downhole logging and seismic data in Shenhu area, South China Sea. Marine and Petroleum Geology, 51: 298–306.
Wegner, S. A., and Campbell, K. J., 2014. Drilling hazard assessment for hydrate bearing sediments including drilling through the bottom-simulating reflectors. Marine and Petroleum Geology, 58: 382–405.
Wu, S., Wong, H. K., and Lüdmann, T., 1999. Gravity-driven sedimentation on the northwest continental slope in South China Sea: Results from high-resolution seismic data and piston cores. Chinese Journal of Oceanology and Limnology, 17 (2): 155–169.
Yu, H. S., 1990. The Pearl River Mouth Basin: A rift basin and its geodynamic relationship with the southeastern Eurasian margin. Tectonophysics, 183 (1-4): 177–186.
Zimmer, M., Prasad, M., and Mavko, G., 2002. Pressure and porosity influences on Vp-Vs ratio in unconsolidated sands. The Leading Edge, 21 (2): 178–183.
Zhang, G. C., Mi, L. J., Wu, S. G., Tao, W. X., He, S. B., and Lv, J. J., 2007. Deepwater area–The new prospecting targets of northern continental margin of South China Sea. Acta Petrolei Sinica, 28 (2): 15–21 (in Chinese with English abstract).
Zhou, W., Wang, Y. M., Gao, X. Z., Zhu, W. L., Xu, Q., Xu, S., Cao, J. Z., and Wu, J., 2015. Architecture, evolution history and controlling factors of the Baiyun submarine canyon system from the middle Miocene to Quaternary in the Pearl River Mouth Basin, northern South China Sea. Marine and Petroleum Geology, 67: 389–407.
Zhu, M., Graham, S., Pang, X., and Mchargue, T., 2010. Characteristics of migrating submarine canyons from the middle miocene to present: Implications for paleoceanographic circulation, northern South China Sea. Marine and Petroleum Geology, 27 (1): 307–319.