关键词: 火山岩相, 储集空间, 成因, 牛东地区, 三塘湖盆地

Abstract:

The exploration of shale gas and coal-bed methane is an important field of the non-conventional gas exploration. The shale gas reservoir formed in dark-colored high-carboniferous argillaceous hydrocarbon source rocks with the mechanism of adsorption-dissolution-free existence. Based on the study result of hydrocarbon source rocks of Sichuan Basin, it is demonstrated that Longtan Formation ofUpper Permian is favorable to form coal-bed methane reservoir. The favorable areas are located in HuayingMountains, and its southeastern side and southern side. The strata of this region mainly contain bituminous coal with the superiority of high gas content and shallow burying. For low gas content, the coal measures of Upper Triassic Xujiahe Formation are favorable for the accumulation of shale gas. There are two advantageous areas: the one includes the periphery ofWeiyuan Anticline （which is located in southwestern Sichuan Basin） and the north part of southern Sichuan Basin, while another area is frontier area of Micang Mountain with shallow buried target. The argillaceous hydrocarbon source sequence of petroliferous strata, being favorable for the accumulation of shale gas, is Lower Jurassic. The favorable areas are located in the precipitous structural flanks and shallowburied fringe of northeastern and northern parts of Sichuan Basin. The dark-colored argillaceous hydrocarbon source rocks of Lower Silurian Longmaxi Formation and Lower Cambrian Qiongzhusi Formation are favorable for the accumulation of shale gas in early-middle maturation period. At present, these sequences are unfavorable to preserve shale gas, due to the sharply increased organic maturity and deeply buried target zones. In frontier side of Daba Mountain and northwestern fringe of Jiangnan Ancient Land, organic maturity has a trend of decrease, so these areas are favorable for accumulation of shale gas too.

Key words: volcanic facies, reservoir space, genetic mechanism, Niudong area, Santanghu Basin