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川东北地区长兴组—飞仙关组发育的台地边缘礁滩相和浅滩相沉积体系,为优质储层发育奠定了基础。储层现今的孔隙类型主要是以粒间孔、晶间孔、生物体腔孔和各种溶蚀孔以及裂缝为主的次生孔隙,原生孔隙已基本被成岩作用所改造,其中晶间孔、溶蚀孔及裂缝是研究区主要的储集空间。在地质历史时期,该区储层主要经历了7种成岩作用,各种成岩作用均对台地边缘礁滩相和浅滩相沉积体系进行了改造,但影响效果较明显的是白云岩化、溶蚀及破裂等作用,其作用结果为优质储层的发育提供了条件:白云岩化作用改造了礁滩相储层孔隙结构,溶蚀作用进一步扩大溶蚀孔洞的发育效果,破裂作用连通孔隙并提供油气运移通道。基于岩心与薄片的鉴定及扫描电镜分析资料,通过对研究区不同岩石类型储集空间发育特征、成岩环境、岩体特征及储层发育条件分析研究,认为礁滩相沉积体系优质储层发育主要受3方面因素控制:礁滩相沉积微相、成岩作用及构造破裂作用。在此控制之下长兴组生物礁滩相储层孔隙分原生孔、晶间孔及早期和晚期埋藏溶解孔4个演化阶段,飞仙关组礁滩相储层孔隙演化与长兴组有着相似的发育过程,但其孔隙类型稍有不同,分为原生孔、鲕模孔/粒内溶孔及浅埋和深埋溶孔4个演化阶段;整体上礁滩相优质储层只有在后期白云岩化、破裂作用及溶蚀作用改造后,才能发育成为优质储层。
The platform facies reefs facies and shoal facies sedimentary systems developed in Changxing Formation-Feixianguan Formation in northeastern Sichuan lay the foundation for the development of high-quality reservoirs. The current pore types of reservoirs are mainly secondary pores mainly composed of intergranular pores, intercrystalline pores, living body pores and various dissolution pores and fractures. Primary pores have been basically modified by diagenesis, in which intercrystalline pores, erosion Pores and cracks are the main storage space in the study area. During geologic history, the reservoirs in this area mainly experienced seven diagenetic processes. Various diagenesis reworked the sedimentary system of reef-shoal facies and shoal facies in the platform margin. However, the more obvious effects are dolomitization, dissolution and The result of this action provides the conditions for the development of high-quality reservoirs: dolomitization rebuilds the pore structure of the reef-shoal facies reservoirs, and the dissolution effect further expands the developmental effect of the dissolved pores. The rupture functions to connect the pores and provide hydrocarbon migration aisle. Based on the identification of cores and thin sections and the analysis of the scanning electron microscope (SEM), through the study on the reservoir space development characteristics, diagenetic environment, rock mass characteristics and reservoir development conditions of different rock types in the study area, it is considered that the development of high-quality reservoirs in the reef- It is controlled by three factors: reef bank sedimentary microfacies, diagenesis and tectonic rupture. Under this control, the phreatic primary pores, intergranular pores and early and late burial dissolution pores of the reef-shoal facies reservoirs in Changxing Formation have four evolution stages. The evolution of pore porosity in Feixianguan reef-shoal facies reservoirs is similar to that of Changxing Formation But their pore types are slightly different. They are divided into four stages: primary pores, oolitic pores / intragranular dissolution pores, shallow buried pores and deep buried dissolved pores. On the whole, the high-quality reservoirs of reef- After the alteration of the tectonic, rupturing and dissolving functions, it can develop into a high-quality reservoir.