Smectite and illite are different with each other from the aspects of specific surface area and microporo-sity. Compared to illite, smectite is more conducive to the occurrence of shale gas. During mudstone diagenesis, compaction and smectite illitization as well as the consequent abnormal pressure could transform the characters of the two minerals, bringing significant influence on the adsorption of shale gas. However, the organic matter in the montmorillonite of the argillaceous source rocks retards the smectite illitization process, making another important impact on shale gas adsorption. Integrating smectite illitization, interlayer organic matter evolution and dehydration process of interlayer water, the study shows that the favorable rich region for shale gas is correlated with the period prior to the stage when interlayer organic matter and water have been discharged, namely from the convertion stage of chaotic mix-layer illite/smectite to the partially ordered mixed-layer illite/smectite ( smectite for 50%-35% in I/S) and the final phase of ordered mixed-layer illite/smectite( smectite for about 15% in I/S) .%页岩气的赋存受多种因素的制约，作为泥质烃源岩中最主要的2种黏土矿物，蒙脱石和伊利石在比表面和微孔隙上存在的明显差异决定了蒙脱石更有利于页岩气的赋存。成岩过程中的压实作用和蒙脱石向伊利石的转化以及由此产生的异常压力都会改变蒙脱石和伊利石的性质，进而影响到对页岩气的吸附。然而，泥质烃源岩中蒙脱石层间有机质的存在，一定程度上延缓了蒙伊化进程，也会对页岩气的吸附产生重要影响。将泥质烃源岩中蒙脱石伊利石化与蒙脱石层间有机质演化以及层间水脱水过程联系起来分析发现，成岩过程中层间有机质排出以前以及层间水排出时期，即从无序伊蒙混层向部分有序混层转化的阶段（伊蒙混层比50％～35％）以及有序伊蒙混层形成的末期（伊蒙混层比15％左右），对应页岩气的有利富集期。
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