Diagenesis and Thermodynamics Analysis in Clastic Reservoir E13 of North Area of West Qaidam Basin
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摘要: 柴达木盆地西部北区E13地层普遍发育了很好的碎屑岩，储层物性与成岩作用密切相关。为了认清柴西北区E13有利储层的分布规律，在岩心观察、显微分析和各种分析化验的基础上，划分了本区成岩作用序列，并通过热力学分析进一步研究了成岩作用的控制因素。研究发现，本区主要存在四次较大规模的成岩作用，第一次是白云石胶结及交代作用，第二次是方解石的胶结与交代作用，第三次是胶结物的溶解，第四次是晚期硬石膏的胶结及交代作用，而油气充注发生在溶解作用之后硬石膏胶结作用之前。另外，压实和压溶作用贯穿整个成岩作用过程。各种成岩作用都是在一定的热力学体系下进行的，通过细致的热力学推导，绘制出包含方解石、白云石和硬石膏等矿物相在内的五组分相图，从而得到了成岩环境的地球化学特征。Abstract: Layer E13 in north area of west Qaidam Basin develops good clastic rock. Reservoir properties and diagenesis have a big relevance. To recognize favorable reservoir in E13 in North area of west Qaidam Basin, we divide diagenesis sequence of this area on the basis of core observation, microscope research and analyses experiments, and research the controlling factors of diagenesis further through thermodynamic analyses. In this area, there are four times of widescale diagenesis mainly. The first is dolomite cementation and replacement. The second is calcite cementation and alternation. The third is dissolution and the fourth is anhydrite cementation and alternation. The oil flow happens between dissolution and anhydrite cementation. In addition, compaction and pressolution run through the whole diagenesis. Each diagenesis proceeds in thermodynamic system. Through carefully deduction, we draw five component phase diagram including calcite, dolomite and anhydrite, etc, and get the geochemistry characteristics of diagenesis environment.
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Key words:
- diagenesis /
- thermodynamic constitutional diagram /
- calcite /
- dolomite /
- anhydrite
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