川东及其周缘地区下寒武统龙王庙组储集层特征与控制因素

根据薄片、阴极发光、扫描电镜、岩石物性等分析化验资料以及测井资料,对川东及其周缘地区下寒武统龙王庙组储集层特征与控制因素进行研究。结果表明:(1)龙王庙组储集层岩性主要为颗粒碳酸盐岩,其次是粉—细晶白云岩。(2)龙王庙组储集层储集空间主要为粒间(溶)孔、晶间(溶)孔、粒内溶孔,构造缝和溶蚀缝发育;储集层基质孔隙度值和渗透率值低,平均值分别为4.25%和6.25×10-3μm2,储集层类型包括孔隙型和裂缝—溶孔型2种。(3)龙王庙组储集层的形成和分布可能受到沉积作用、成岩作用、埋藏过程等3种控制因素的共同影响:沉积作用提供了储集层发育的地质基础;成岩作用是影响储集层发育的关键因素;埋藏方式影响储集层的最终形成,是川东地区龙王庙组储集层质量差于川中及川东南地区的原因之一。(4)综合储集层的岩性、物性、厚度及分布范围,认为川东及其周缘地区龙王庙组储集层以局限台地内滩体最为有利,局限潮坪次之。

Characteristics and controlling factors of the Lower Cambrian Longwangmiao Formation reservoirs in easternSichuan Basin and its adjacent areas

In order to study the characteristics and controlling factors of the reservoirs in the Lower Cambrian Longwangmiao Formation in eastern Sichuan Basin and its adjacent areas,we analyzed the laboratory data of thin sections,cathode luminescence,scanning electron microscope and physical properties, and log data. The result shows that: (1)The main types of reservoir rocks of the Longwangmiao Formation are grain carbonate rocks,and silty-fine crystalline dolostones following. (2)The main types of reservoir space of the Longwangmiao Formation are intergranular(dissolved)pores,intercrystalline(dissolved)pores,intragranular dissolved pores,followed by structural fractures,dissolution fracture. The reservoirs have low porosity and permeability with average matrix porosity of 4.25％ and permeability of 6.25×10^-3μm²; The reservoirs could be divided into two types: the porous type and the fractured-dissolution-porous type. (3)The formation and distribution of the reservoirs in the Longwangmiao Formation may be influenced by three controlling factors including sedimentation,diagenesis and burial process. Sedimentation provided the geological background for the reservoir development;diagenesis was the key factor influencing the reservoir development;and the burying process,which is one of the reasons why the reservoirs in eastern Sichuan Basin have poor quality comparing with those in central and southeastern Sichuan Basin,affected the formation of the reservoirs eventually. (4)It was concluded that the favorable reservoirs were developed mainly in the banks,and secondly in the tidal flats of the restricted platform, overall, considering the lithology, physical property, thickness and distribution range synthetically.