鄂尔多斯盆地志丹油田永金地区长6储层成岩作用类型及演化

Diagenesis Types and Evolution of Chang 6 Reservoir in Zhidan Oilfield Yongjin Area of Ordos Basin

通过铸体薄片、扫描电镜、X射线衍射及压汞等资料分析,研究志丹油田永金地区长6砂岩储层成岩作用类型及成岩序列。研究结果表明,强烈的压实、压溶作用及胶结作用导致原始孔隙丧失殆尽,使形成超低渗储层的主要原因。而溶蚀作用的存在,特别是长石溶蚀形成大量次生孔隙,对改善砂岩储集物性起到决定性作用。并且认为长6砂岩成岩演化主体处于晚成岩A期,部分指标已进入晚成岩B初期。在此基础上,进一步综合研究了成岩演化及孔隙演化模式。

By means of casting thin sections,scanning electron microscope and X-ray diffraction,and mercury porosimetry,the sandstone diagenesis of Zhidan oilfield Yongjin area was studied.The result shows that mechanical compaction,pressure solution,cementation and dissolution have strong influences on the reservoir qualities,original porosities has lost,which is the major cause to form the low permeability reservoir.Corrosion effect,especially abundant secondary porosities formed by corrosion of feldspar,play a decisive role in improving physical properties of sandstone reservoir.Chang 6 has experienced the late stage of diagenetic A,part has entered the late stage of diagenetic B.Furthermore,mode of diagenesis and porosity evolution were discussed.