通过岩心观察、铸体薄片鉴定、物性分析、现场录井、测井和地震资料，分析川东北元坝地区珍珠冲段的沉积环境和储层特征。元坝地区珍珠冲段为扇三角洲环境，主要发育扇三角洲平原和前缘亚相，受印支期晚幕造山带抬升影响，物缘供给充分，扇三角洲平原在研究区内广泛发育，仅在西南部发育小范围的前缘沉积，前扇三角洲在研究区内不发育。珍珠冲段储层属于低孔低渗致密型，孔渗关系匹配较好，局部受裂缝影响出现在孔隙度不高的情况下渗透率成倍增大的情况。原生粒间孔、粒间和粒内溶孔等有效储集空间类型在珍珠冲段下部的砂砾岩河道微相中十分发育，其中裂缝发育极大地提高了储层的储集性能，所以河道微相展布区、裂缝发育带的叠合区域即为相对优质储层发育区。珍珠冲段沉积作用对储层的影响主要体现在孔隙、裂缝发育两个方面，不仅对储层起到先天性的控制作用，也是后期裂缝发育的物质基础。%Through core observation,casting thin sections identification,physical properties analysis, logging and seismic data,the authors deeply research the sedimentary environment and reservoir characteristics of the Lower Jurassic Zhenzhuchong segment in the Yuanba area,Northeast Sichuan Basin.The Zhenzhuchong segment is a fan delta environment.It can be divided into fan delta plain and fan delta front.Because of the Indosinian orogeny,the orogenic belt lifts,and meanwhile provides abundant sediments,the fan delta plain is distributed widely.The fan delta front only grows in the southwest of the research area.But the former fan delta does not develop in the study area.The reservoir of the Zhenzhuchong segment is low porosity and low permeability.Its correlation of porosity and permeability matches very well.The few situations are high permeability under the low porosity owing to the structural fractures. The protogenetic intergranular pore, intergranular dissolution pore and intragranular dissolved pore develop well in the conglomerate rock of the river microfacies at the bottom of the Zhenzhuchong segment.And the fractures improve the reservoir performance tremendously.So the relative high quality reservoir of the Zhenzhuchong segment is the composite area of river microfacies distribution area and fracture development zone in the Yuanba area.The influence of sedimentation on the reservoir has two aspects including pore and fracture.So the sedimentation not only controls the primitiveness of the reservoir,but also provides the material basis for the fracture development.
展开▼
