Reef Palaeopool and Prediction of Buried Reefs in the Lower Permian Series from Shiwandashan Basin of Guangxi Province
Chen Xueshi and Geng Zhongxia(Hangzhou Institute of Petroleum Geology, CNPC, 310023)
The Tingliang reef palaeopool of the lower Permian Maokou Formation is one of the destroyed oilpools in the Shiwandashan basin of Guangxi province,and its bitumen-bearing reservoir (above 98 meters in the thickness) occurs mainly in the upper part and at the top of the reef body. The formation and distribution of the secondary solution porosity of this reef are mainly controlled by organic solution. and they are also spatially related to the weathering palaeocrust of the unconformity. This paper describes the burial history, thermal history, diagenetic porosity evolution history and their relations with this reef. The diagenetic types and the oil pool-forming mechanism of this reef are also discussed. Seismic profiling reveals 31 "reef" anomalous bodies in the northeastern basin and 9 are found by electrical prospecting. They occur in the same region and overlap one another. The exposed reefs and the buried "reefs" lie in the same palaeolitho-geographic zone, suggesting that there may be a buried reef zone of the lower Permian platform margin type in the Shangying-Tai'an area. We also found that the zone of oil and gas extends for 150 km in the northern basin. Therefore, we should pay more attention to the study of buried reef oil pools, because they might be a promising new field in petroleum prospecting of the Shiwandashan basin.
【CateGory Index】： P618.13