The role of polygonal faults in fluid migration and gas hydrate reservoir forming in Southeast Hainan Basin
Wang Xiu-juan1,2,5, Wu Shi-guo1, Wang Da-wei1, Ma Yu-bo1, Yao Gen-shun Gong Yue-hua1,3
1. Key Laboratory of Marine Geology and Environment,Institute of Oceanology,China Academy of Sciences,Qindao City,Shandong Province 266071,China;
2. Key Laboratory of Marginal Sea Geology,China Academy of Sciences,Guangzhou City,Guangdong Province 510301,China;
3. Hangzhou Geology Institute,Research Institute of Petroleum Exploration & Development of PetroChina,Hangzhou City,Zhejiang Province 310023,China;
4. Guangzhou Marine Geological Survey,Guangzhou City,Guangdong Province 510760,China
Abstract：The dehydration of unconsolidated sediments made the sediments shrink,then the polygonal faults were formed,they were the densely distributed tensional faults with small fault throws.In the Miocene to Pliocene strata in the deep water zone of Southeast Hainan Basin,the small-scale fluid migration channels which actually were the polygonal faults were found on the 2-D high resolution seismic coherence slices.Meanwhile the polygonal faults,diapir and event pulldown tubular structures were found on the 2-D high resolution seismic sections,and the strong BSR (Bottom Simulating Reflector) exist 250ms to 300ms below the sea floor.The CSSI (Constrained Sparse Spike Inversion) and seismic attribute analysis show that tubular structures and fuzzy reflection zone in the strata above the polygonal faults have low impedance anomaly and low frequency anomaly,while the BSR shows high impedance anomaly and high frequency anomaly.The polygonal faults,diapir and event pulldown tubular structures broke the closure of the extremely thick mudstone strata during the post-fault thermal subsidence period in Southeast Hainan Basin,the structures made a large amount of fluid migrate upwards vertically or nearly vertically,providing sufficient gas source for the gas hydrate formation.
王秀娟, 吴时国, 王大伟, 马玉波, 姚根顺, 龚跃华. 琼东南盆地多边形断层在流体运移和天然气水合物成藏中的作用[J]. 石油地球物理勘探, 2010, 45(1): 122-128.
Wang Xiu-juan, Wu Shi-guo, Wang Da-wei, Ma Yu-bo, Yao Gen-shun Gong Yue-hua. The role of polygonal faults in fluid migration and gas hydrate reservoir forming in Southeast Hainan Basin. OGP, 2010, 45(1): 122-128.
