致密碎屑岩气藏成藏机理深化研究及开发应用——以新场气田须二段气藏为例

四川盆地新场气田上三叠统须家河组须二段气藏的储层非均质性强、气水分布状况复杂，严重地制约了气藏高效开发，而前期的基础地质研究并未真正探明优质储层和气水分布规律。为此，以深究气藏复杂气水分布的根源为出发点，以梳理前期成藏研究成果为基线，融入气藏动静态特征，分阶段深化成藏规律研究，探寻气藏储层非均质性及复杂气水分布的根源，明确成藏富集高产主控因素和气藏开发潜力方向。研究结果表明：须二段气藏成藏的关键时期为晚期高压驱赶运聚成藏阶段，早期古构造叠加晚期“断而未破”的裂缝系统是高压驱赶天然气成藏富集高产的主控因素；储层组分非均质性是储层后期成岩作用复杂化的基础，非均质储层叠加多期构造运动造就了须二段气藏现今复杂的储层及气水分布。现场应用效果进一步验证了该成藏机理深化研究成果的可靠性，为须二段气藏有效开发指明了潜力方向，对同类气藏开发具有借鉴作用。

A deep investigation into tight clastic gas pooling mechanism and its application:A case study of the 2nd member of the Xujiahe Formation gas reservoirs in the Xinchang Gas Field.Sichuan Basin

Great heterogeneity and complex gas water distribution have severely restricted the highly efficient development of gas reservoirs in the 2^nd member of the upper Triassic Xujiahe Formation, Xinchang Gas Field, Sichuan Basin. Beyond that, the early basic geological studies did not discover the real quality reservoirs and the gas water distribution law. In view of this, based on the previous research results, this paper first made a deep study in stages of gas reservoir forming regularity, then explored the root cause of heterogeneity of reservoirs and the complex gas water distribution, and finally disclosed the main controlling factors of gas accumulation and high gas deliverability and the potential targets of gas reservoir development. The following findings were obtained in this study area. a. The gas pooling was motivated by high pressure at the essential later period. The later period fracture system, which was broken but not in fragment, and which resulted from the superposition of early paleostructures, is the main controlling factor of gas accumulation and high gas deliverability driven by high pressure. b. The heterogeneity of reservoir components leads to the complexity of diagenesis in the later period of gas pooling; the superposition of heterogeneous reservoirs after multi stage tectonic movements results in the present complexity of reservoirs and gas water distribution. Field application has further validated the reliability of the above findings, providing the prospective targets for effective development of gas reservoirs in this study area. This study provides a reference to the development of similar gas reservoirs in China.