四川盆地蓬探1井区震旦系灯影组二段储层特征及主控因素

Reservoir characteristics and main controlling factors of the second member of the Dengying Formation in Pengtan 1 well area, Sichuan Basin

四川盆地蓬探1井区灯影组气藏是继安岳气田发现后的又一勘探成果,在灯二段中发现了储量可观的工业气藏。明确该气藏的储层特征及成因机制对优质储层的分布预测、开发方案的制定及下步勘探部署具有重要意义。利用岩心、物性分析、测井解释、成像测井及地震资料对蓬探1井区灯二段储层特征进行了刻画,剖析了其成因主控因素,研究结果表明:灯二段优质储层主要发育于与生物建造相关的藻白云岩和与颗粒滩建造相关的颗粒白云岩中,储集空间有孔隙、溶洞和裂缝等类型。按储集空间的组合特征可将储层分为孔隙型、溶洞型及缝洞型3类,缝洞储层最发育,其次为溶洞型。优质储层主要分布在灯二段的中上部,总体表现为低孔低渗,部分井段表现为中孔中渗的特点。优质储层的发育程度及空间展布主要受沉积微相、早成岩期岩溶作用及桐湾运动的影响。处于台缘亚相带的丘滩体微相是优质储层的发育相带,早成岩期岩溶作用促进了储集空间进一步发育,桐湾运动促进了裂缝的发育和大气淡水淋滤作用的进一步发生。

The Dengying Formation(Z2dn)gas reservoir in Pengtan 1 well area is another exploration achievement after the discovery of Anyue Gas Field.It is of great significance to clarify the reservoir characteristics and genetic mechanism of this gas reservoir for the distribution prediction of high-quality reservoirs,the formulation of development plan and the next exploration deployment.Based on core,physical property analysis,logging interpretation,imaging logging and seismic data,the reservoir characteristics of the second member of Dengying Formation(Z2dn~2)in Pengtan 1 well area are described and the main controlling factors are analyzed.The results show that:The high quality reservoir of Z2dn~2 is mainly developed in algal dolostone related to biogenesis and granular dolostone related to grain beach formation.The reservoir space includes pores,caves and fractures.According to the combination characteristics of reservoir space,the reservoir can be divided into three types:Pore type,karst cave type and fracture-cave type.The fracture-cave reservoir is the most developed,followed by karst cave type.The high quality reservoirs are mainly distributed in the middle and upper part of Z2dn~2,which are generally characterized by low porosity and low permeability,and some sections are characterized by mid-porosity and mid-permeability.The development degree and spatial distribution of high-quality reservoirs are mainly affected by sedimentary microfacies,karstification during early diagenesis and Tongwan movement.The dune beach microfacies in the platform margin subfacies zone is the development facies zone of high quality reservoir.Karstification in early diagenetic stage promoted the further development of reservoir space,and Tongwan movement promoted the development of fractures and the further occurrence of atmospheric water leaching.