蜀南低缓构造区须家河组岩性气藏形成条件与勘探潜力

与四川盆地川中地区须家河组岩性气藏相对比，近年来蜀南地区须家河组勘探和开发一直没有获得重大突破，蜀南低缓构造区须家河组是否存在岩性气藏形成条件和勘探潜力一直为众人所关注。综合分析露头、岩心和测井资料，并通过对该区须家河组构造背景、沉积砂体、烃源岩和储层等成藏条件、成藏主控因素研究认为：蜀南低缓构造之间存在大面积地层平缓区，具备大面积岩性气藏形成的构造背景；须家河组一段、三段、五段及六段二亚段为广覆式分布烃源岩，具备面式生烃特征，为岩性气藏的形成奠定气源基础；大型敞流型湖盆内须二段、须四段、须六段一亚段和须六段三亚段以砂岩沉积为主，砂体分布广并多层叠置，具备较好储集条件；源岩层与储集层间互沉积，源储一体使蜀南须家河组与川中须家河组具有相似的面状供烃、近源高效聚集成藏特征。蜀南地区须家河组具备岩性气藏形成基础，可形成大规模岩性大气区，勘探潜力巨大。该认识为低缓构造区须家河组勘探部署提供充分地质依据，并指明低缓构造之间的平缓区域是下一步勘探重要领域。

Lithologic gas reservoir formation and exploration potential of the Xujiahe Formation in gently structured zones,southern Sichuan Basin

There is no significant breakthrough in the exploration and development of the Xujiahe Formation in Shunan area in recent years compared with that of lithologic gas reservoir of the Xujiahe Formation in the central Sichuan Basin.Thus the lithologic gas reservoir forming conditions and exploration potential of the Xujiahe Formation in gently structured zones of Shunan area have always been the focus of attention.With the integrated analysis of outcrop,core and logging data,and the investigation of various accumulating conditions and major controlling factors,such as tectonic setting,sedimentary sandbody development,source rock presence,reservoir characteristics and etc.of the Xujiiahe Formation in this area,we believe that:(1) a large area of flat laying strata in the tectonically quiescent area is favorable for forming lithologic gas reservoirs;(2) the source rocks capable of large area hydrocarbon generation are distributed widely in the 1^st,3^rd,5^th member and the 2^nd submember of the 6^th member of the Xujiahe Formation,providing the gas source for lithologic accumulation;(3) the 2^nd,4^th member and the 1^st,6^th submember of the 6^th member of the Xujiahe Formation in the large-scale open flow lacustrine basin mainly are sandstones that are widespread and present in multiple zones,favorable for reservoir formation;(4) source beds and reservoirs interbeddedly deposit,resulting in similar accumulating features to the Xujiahe Formations in the central Sichuan Basin,i.e.large area continuous source kitchen hydrocarbon supply and efficient near-source charge.We believe that the Xujiahe Formation in the Shunan area has the conditions favorable for lithologic gas accumulating and may have formed a large-scale gas accumulation area.The understanding provides the geological basis for the exploration deployment of the Xujiahe Formation in tectonically quiescent zones,and indicates that the gently structured area between the low structures will be a focus for further exploration.