摘要
沉积格架与储层质量关系研究较少,综合运用岩心、测井及地球化学分析资料,对镇泾地区长_8~1和长_8~2小层沉积格架与储层质量关系进行研究。研究结果表明:根据单套砂体与有效泥岩隔夹层发育情况,长_8~1和长_8~2小层沉积格架可划分为单层式、夹层式和互层式3类;储层质量较好段多位于单套式砂体中部;单套砂体的厚度与储层质量较好段的厚度、物性呈明显的正相关关系,当单套砂体厚度小于7 m时,储层质量较好段基本不发育;压实和钙质胶结作用是储层质量受控于沉积格架的主要机理,压实作用从整体上控制了储层质量,砂体厚度大更有利于储集空间保存,从而形成优质储层,单套砂体顶底部钙质胶结比较发育,钙质胶结砂岩的厚度与相邻泥岩隔夹层的厚度相关性较好;砂岩与相邻泥岩碳氧同位素表明泥岩的压实排水是钙质胶结形成的主要原因。该研究建立了不同类型沉积格架与储层质量的关系,阐明了储层质量受控于沉积格架的机理,为少井条件下有利区优选奠定了基础。
The relationship between sedimentary framework and reservoir quality is less studied. In the paper,the core,well logging and geochemical analysis data were used to sudy the relationship between sedimentary framework and reservoir quality of Chang_8~1 and Chang_8~2 sublayers in Zhenjing area. The study results show that the sedimentary framework of Chang_8~1 and Chang_8~2 sublayers can be divided into 3 types like single layer type,sandwich-type and interbed-type based on the developmental state of single sand body and effective mudstone barrier/interbed;the interval with good reservoir quality is mostly located in the middle of single sand body; the thickness of single sand body is positively correlated with the thickness and physical properties of interval with good reservoir quality,and when the thickness of single sand body is less than 7 m,the interval with good reservoir quality is basically not developed; the compaction and calcitic cementation are the main mechanisms for the reservoir quality to be controlled by sedimentary framework,the compaction controls the reservoir quality as a whole,the large thickness of sand body is more favorable for the preservation of reservoir space,thus forming high quality reservoirs,the calcitic cementation is relatively developed at the top and bottom of single sand body,and the thickness of calcite cemented sandstone has a good relationship with the thickness of adjacent mudstone barrier/interbed; the carbon and oxygen isotopes of sandstone and adjacent mudstone indicate that the compaction and drainage of mudstone are the main cause of calcitic cementation. This study establishes the relationship between different types of sedimentary frameworks and reservoir quality,clarifies the mechanism of reservoir quality controlled by sedimentary framework,and lays a foundation for optimal selection of favorable areas under the condition of few wells.
引文
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