摘要： 川西新场构造带上三叠统须家河组二段砂体分布广泛、砂体类型多样且厚度差异较大,导致气藏层间隔层、层内夹层分布不均,储集层分布非均质性强烈,因此需对储集砂体沉积微相与砂体分布特征及砂体结构展开精细研究,为下一步储集层预测和气藏高效开发奠定基础。作者以Cross高分辨率层序地层学理论为指导,结合岩心、测(录)井、三维地震、分析测试等资料,系统阐明了川西新场构造带须二段砂体结构特征及其控制因素。研究结果表明: 研究区整体处于浅水三角洲前缘亚相带,主要发育水下分流河道砂体,河口坝砂体次之,河道砂体侧向迁移频繁,垂向多期叠置、横向上广覆连片。不同位置水下分流河道特征差异大,结合其典型特征,将水下分流河道砂体进一步细分为削截型水下分流河道和完整型水下分流河道。总结出研究区共发育2大类9小类砂体垂向叠置样式和3种侧向接触样式。砂体结构特征和发育样式主要受基准面升降、河流能量控制。最终建立了川西新场构造带须二段沉积微相及砂体结构发育模式,这对浅水三角洲前缘的气藏勘探开发具有指导意义。

关键词: 砂体结构, 叠置样式, 接触关系, 浅水三角洲前缘, 上三叠统, 须家河组, 新场构造带

Abstract: The sand bodies of the Member 2 of the Upper Triassic Xujiahe Formation in the Xinchang structural belt of western Sichuan Basin are widely distributed,with various types of sand bodies and large thickness differences. This results in uneven distribution of interlayer barrier bed and intraformational bed in gas reservoirs,and strong reservoir heterogeneity. Therefore,it is crucial to investigate the sedimentary microfacies,distribution characteristics and architecture of reservoir sand bodies,so as to lay a foundation for the following reservoir prediction and efficient gas reservoir development. Using core,well logs,3D seismic and laboratory data,and guided by the theory of high-resolution sequence stratigraphy proposed by T.A. Cross,the authors systematically examined the structural characteristics and controlling factors of sand bodies in the second member of Xujiahe Formation in the Xinchang structural belt,western Sichuan Basin. The results show that: The study area was largely located in a shallow water delta front environment,which consists mainly of subaqueous distributary channel sand bodies with subordinate mouth bar sand bodies. These channel sand bodies are characterized by frequent lateral migration,multiple vertical amalgamation and extensive areal coverage. It is concluded that in the study area there are two main categories and nine subcategories of sand body vertical stacking patterns and three lateral contact patterns. The structural characteristics and development patterns of sand bodies are controlled mainly by base-level fluctuation and river energy. Finally,the sedimentary facies and sand body development model of the Xinchang structural belt in western Sichuan Basin are established,which has important applications for guiding exploration and development of gas reservoirs in similar settings.

Key words: sand body achitecture, superimposed style, lateral contact, shallow water delta front, Upper Triassic, Xujiahe Formation, Xinchang structural belt

中图分类号: 

• P588.21