摘要:
充分利用普通薄片、铸体薄片、X-衍射和扫描电镜等资料,对库车坳陷克深地区白垩系巴什基奇克组储层的岩石学、物性和储集空间等特征进行了研究;并结合元素俘获测井ECS等资料,对层序边界附近的成岩作用和成岩矿物组合特征进行了探讨,同时对比分析了巴二段湖侵体系域和巴一段高位体系域内的成岩作用进程的差异。结果表明,层序界面下薄片中普遍可见溶蚀现象,表现在界面附近长石岩屑含量减少,且靠近层序界面储层物性变好。最大湖泛面处由于沉积因素致其具有较高的黏土含量,而层序界面之下与溶蚀伴生的高岭石的成岩转化造就了层序界面之下也具有较高的黏土含量。总体上层序界面和体系域对碳酸盐岩胶结作用的控制并不明显,在层序的各个部位均可见较高或较低碳酸盐岩含量,主要与研究区的碱性成岩环境有关。研究成果有利于研究区有利储层的追踪对比和预测工作,在指导天然气勘探的同时也能促进成岩层序地层学理论的发展。
Abstract:
On the basis of thin section, casting thin sections, X-diffration and scanning electron microscope data, this article discusses reservoir properties including lithology, physical property and reservoir space of the Cretaceous Bashijiqike Formation in Dabei area of the Kuqa Depression. Combining with Elemental Capture Spectroscopy (ECS) logging, diagenesis and characteristics of diagenetic mineral assembladges were studied. The difference of diagenesis between Ba 2 (the second member of Bashijiqike Formation) transgressive system tract and Ba 1 highstand system tract is also analyzed. The results show that corrosion phenomena are widely observed in the thin sections, with the decrease of feldspathic litharenite content near the boundary and improvement of physical property near sequence boundary. The clay content is higher both at the maximum flooding surfaces due to deposition, and under the sequence boundaries due to kaolinization after corrosion. On the whole, the controls of sequence boundaries and system tracts on carbonate cementation are not obvious. Different contents of carbonate cement could be seen in every part of sequence, which are related to alkaline diagenetic environment of the study area. Study results are beneficial for the track and comparison of reservoirs; Moreover, these would direct the exploration of gas and promote the development of the sequence stratigraphy theory.
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