四川盆地普光大型气田H2S及优质储层形成机理探讨——读马永生教授的“四川盆地普光大型气田的发现与勘探启示”有感

四川盆地普光大型气田的发现刷新了中国海相碳酸盐岩油气田的多项记录：储量规模最大、储层埋藏最深、资源丰度最高，同时也是中国原油裂解气藏规模最大、天然气最于、硫化氢储量最多的气藏；另外它还是中国目前发现的碳酸盐岩储层次生孔隙最发育的气藏。深入研究后发现，普光超大型气藏的形成具有特殊的地质地球化学条件，即充沛的烃源、储层附近发育一定的膏质岩类、储层经历过较大的埋深〈较高的温度），这些条件是硫酸盐热化学还原作用（thermochemical sulfate reduction，简称TSR，）发生所必须具备的；而正是由于TSR的发生，一方面形成了富含H2S、CO2等酸性气体的流体；同时TSR过程及其形成的硫化氢等酸性流体具有腐蚀性，对深部碳酸盐岩储层进行强烈的溶蚀改造作用，促进了次生大孔洞的发育和优质储层的形成，因此TSR的发生是普光大型气田形成的关键因素之一。

Probe into Formation Mechanism of H2S and High-quality Reservoirs of Puguang Large Gas Field in Sichuan Basin--The New Cognition after Reading Professor Ma's Paper "Discovery of the Large-scale Gas Field in the Sichuan Basin and Its Enlightenment for Hydrocarbon Prospecting"

The Puguang large-scale gas field in Sichuan basin has rewritten multinomial records of China marine carbonate oil and gas fields, which are the gas field of the largest scale reserves, the deepest reservoirs and the highest richness, also the one of large-scale cracked gas from oil, the driest gas and hightest H_2S-bearing. At present, the Puguang gas field developed best the secondary porosity in China. By passing further research, we found the large-scale gas field need special geological and geochemical conditions: abundant hydrocarbon source, gypsolith within reservoirs and suffering bigger burial depth (higher temperature). These conditions are necessary to TSR (thermochemical sulfate reduction) occurrence. Because of the TSR occurrence, the reaction occur acidic fluid with abundant H_2S and CO_2, meanwhile the TSR and its acidic fluids products (H_2S, etc) have strong corrosion, which alternated acutely the deep carbonate reservoir and improve the secondary poroes formation and and high quality reservoirs, So, the TSR occurrence is one of the key factors of Puguang gas field formation.