Research On Destruction Of Tectonic Movements On Oil And Gas Reservoirs In Xianggui Area

Xianggui Area is divided into Nanpanjiang Depression, Xiangzhong Depression,Guizhong Depression and three reverse first-order structural units of Shiwanshan Basin. Several units of mature source rocks, which were discoveried in Cambrian, Devonian, Carboniferous and Permian strata, provided good conditions for oil and gas accumulation. However, although the source rocks were buried deeply and matured early, because of the subsequent multi-stage severe constructural movements, the oil and gas reservoirs were destroyed after their accumulation and the ancient oil and gas reservoirs and oil seepages are exposed in the air. The experience confirms that the subsequent constructural movements mainly restrict the oil and gas explorations. The study of many ancient oil and gas reservoirs reveal that different structural units in Xianggui Area had different controls of reservoir destruction. The ancient oil and gas reservoirs are distributed along the discordogenic faults in Nanpanjiang Depression, where the key control of reservoir destruction was fault movement. In Xiangzhong Depression and Guizhong Depression, The ancient oil and gas reservoirs and seepages are exposed and the regional seals were eroded, where the key control of reservoir destruction was structural uplift and erosion. In Shiwanshan Basin, the residual hydrobarbon is solid bitumen, the vitrinite reflectance of which are above 2.0 mostly, and the calculated highest pyrolysis temperatures were above 200℃, meanwhile, the distribution of ancient oil and gas reservoirs coincide with the distribution of Indosinian magmatic rocks, so the key control of reservoir destruction was magmatic activity.