大牛地气田低渗储层成因及评价

综合利用岩芯、测井以及各种分析化验资料，运用储层沉积学、岩石学和成岩作用等相关理论，详细总结了大牛地气田致密砂岩储层的成因。研究结果表明，沉积微相在宏观上控制了储层物性的空间分布，成岩作用决定了砂岩内部储集空间特征和储集性能，主要表现在较强的压实作用和胶结作用使砂岩的原生孔隙很少得以保存，而溶蚀作用有条件地改善了储层的储集性能，微裂缝只是在一定程度上改善了砂岩的渗透性，但也加剧了储层的非均质性。在此研究基础上，从沉积相、岩石学特征、成岩作用、孔渗特征等方面优选地质评价参数，在目的层划分出4类储层，其中Ⅰ类高产层主要是河道砂体复合带，其具有自然伽马曲线低值、自然电位曲线显著负异常等测井响应特征，碎屑颗粒粗，储层岩石表现为石英含量高，以残余粒间孔或粒间溶孔为主的特征。

RESERVIOR GENESIS AND EVALUATION FOR THE LOW POROSITY AND PERMEABILITY SANDSTONE IN THE DANIUDI GASFIELD

Taking the Daniudi Gasfield as an example，the genesis of the physical property of the tight sand stone reservoir is discussed in detail by comprehensively studying on these sedimentology，lithology and diageneses of the reservoir based on core，well logging，and chemical examination data.It showes that the distribution of microfacies decides the spatial distribution of reservoir property，while diageneses controls the reservoir space characteristics and capability in which compaction and cementation has damaging action on the preservation of original intergranular pore，and hence they reduce the porosity and permeability of the reservoir.While corrosion improves the physical property of the reservoir in certain extent and microcrevasse improves permeability of the reservoir and intensified the reservoir anisotropism.From the deposition，the rock，the diagenesis，physical property，choosing geology appraisal parameters，four kinds of reservoir are divided in the goal reservoir，in which prolific zoneⅠis mainly the river course granulated substance body compound belt that has the characteristics of low value GR curve，remarkably negative abnormal SP curve，thick detritus pellet，high quartz content，and remaining intergranular hole or intergranular dissolution pore.