四川盆地中三叠统雷口坡组天然气来源及勘探方向

四川盆地中三叠统雷口坡组天然气勘探近年来取得重要突破后继而成为业内关注的热点，但对气源的认识存在较大的分歧。基于天然气地球化学特征开展的成因鉴别和气源对比研究表明，雷口坡组天然气既有主要来自下伏上二叠统龙潭组/吴家坪组烃源岩（磨溪雷一段气藏），断裂下盘须一段烃源岩有一定贡献（中坝雷三段气藏）或供烃条件（川西雷四段气藏），也有主要来自须家河组烃源岩，雷口坡组自身烃源岩有一定贡献（元坝和龙岗雷四段气藏）。雷口坡组气藏具有3种不同的源储组合，其天然气勘探方向具有差异。上二叠统龙潭组烃源岩作为主力烃源岩构成下生上储型，切穿龙潭组至雷口坡组的深断裂周缘的正向构造是寻找雷口坡组规模性气藏的最有利区。上三叠统须家河组底部烃源岩和雷口坡组顶部储层可以构成旁生侧储型，岩溶残丘或岩溶斜坡局部构造高点是这类组合较有利的发育部位。雷口坡组自身构成自生自储型，这类组合往往作为辅助参与气藏形成。

Gas source and exploration direction of the Middle Triassic Leikoupo Formation in the Sichuan Basin

Natural gas exploration in the Middle Triassic Leikoupo Formation (T₂l) in the Sichuan Basin has achieved great breakthrough in recent years and thus attracts wide attention, however, there is no consensus on the gas source. The genetic identification and gas-source correlation based on the geochemical characteristics of natural gas indicate that, natural gas in the Leikoupo Formation is mainly from the underlying Upper Permian Longtan/Wujiaping Formation (P₃l/P₃w) source rocks (Moxi), with assistance (Zhongba) or hydrocarbon supply condition (Chuanxi) by the source rocks in the 1st Member of the Upper Triassic Xujiahe Formation (T₃x), or mainly from the T₃x source rocks with certain contribution by the T₂l source rocks (Yuanba and Longgang). The T₂l gas pools display three types of source-reservoir assemblages, and they suggest different exploration directions. The P₃l source rocks as main source rocks can constitute the lower-generation and upper-accumulation pattern, and the positive structures around the deep faults connecting the P₃l and T₂l are the most favorable areas to explore large-scale T₂l gas pools. The source rocks at the bottom of T₃x and the reservoirs at the top of the T₂l can constitute the side-generation and side-accumulation pattern, which is favorably developed in the karst residual hills or the local tectonic high position of the karst slope. The T₂l can constitute self-generation and self-accumulation pattern, which tends to participate assistantly in the formation of gas pools.