低渗透储层成岩储集相及储集空间演化模式

Diagenetic reservoir facies and pore space evolution pattern of low permeability reservoir

关键词:  砂西油田  古近系  下干柴沟组  成岩作用  成岩储集相  储集空间演化

Key words:  Shaxi Oilfieldj Paleogene  lower Ganchaigou formation  diagene^is  diagenetic reservoir

摘要:

以砂西油田古近系下干柴沟组下段(E丨)为例，综合应用取心井的岩石铸体薄片、图像分析、扫描电镜、电子探: 针能谱、阴极发光、粘土矿物X衍射分析、镜质体反射率等实骑测试资料,对E丨储层的成岩作用、成岩演化序列和成 岩阶段划分方法进行了研究,分析了低渗透储层成岩作用对储集物性的影响,详细阐述了低渗透储层中各类成岩储 _集相的特征及其形成机制，并探讨了其储集空间类型及演化模式。研究结果表明,本区储层砂岩较低渗透率的主要 成因是成岩期各种自生矿物的充填和胶结作用。根据成岩作用及其特有的储集空间组合，可将E丨储层划分为4种 成岩储集相类型,即不稳定组分中强溶解次生孔暸成岩储集相(A相)、中等胶结中强压实残余粒间孔成岩储集相(B 相)，碳酸盐强晈结成岩储集相(C相)和早期硬石音强胶结成岩储集相(D相)，其中A类储集相的储集性能最好,D 类最差，为差储层或非储层。

Abstract:

2Taking first member of lower Ganchaigou formation of Paleogene { Ej) at Shaxi Oilfield as an example + the diagen-esis，diagenetic sequences and stages were studied, based an the analytic data of casting thin section, image analysis, scan-. ning electron microscope, electron probe energy spectrometry, cathodoluminescence microscope, X-ray diffraction of clay minerals, vilrinile reflectivity of well core samples. The effects of low peimeability reservoir diagenesis on the reservoir properties were analyzed. The characteristics and forming mechanism of each diagenetic reservoir facies were expatiated on, and the pore space types and evolution pattern were discussed. The resulte indicate thal the forming mechanism of the low permeability in thia area is the filling and cementation of autogenetic mineral during diagenesia. According to the 出agenesis and characteristic pore space combinaiion t the reservoir rocks of Ej can be divided into four types of diagenetic reservoir facies (DRF). DRF A is middle to strong dissolution of unstable ingredients to form eecondary pores. DRF B is middle to strong compaction and middle cementation with residual intergranular pores. DRF C is strong carbonate cementation. DRF D is strong cementation of early anhydrite. The reservoir properties of type A diagenetic reservoir facies are the best, while that of type D are the worst and they are poor reservoirs or non-reservoirs.