川东地区冯家湾区块石炭系储层特征及主控因素

Characteristics and Main Controlling Factors in Carboniferous Reservoirs of Fengjiawan Block in Eastern Sichuan Basin

川东地区冯家湾区块石炭系埋藏深度大、时间跨度长、经历多期不同程度的构造改造,新一轮地震资料对区内构造有了新的认识,有必要对区内储层进一步深入研究。通过对岩心及薄片的观察和分析化验资料的研究发现,区内岩石类型多样,主要储集岩由不同类型的颗粒白云岩组成,储集空间以晶间(溶)孔、粒间(溶)孔、角砾内/间(晶间)溶孔为主;孔隙度为0.28%~21.94%,平均4.63%,渗透率为0.001~39.60mD,平均0.51mD,为低孔、低渗裂缝孔隙型储层,孔隙度与渗透率表现出较好的正相关性;研究区储层发育受沉积相、岩石类型、白云石化、古岩溶和构造裂缝等因素的控制。高能滩相环境中的颗粒白云岩为储层发育提供了有利的物质基础,控制着储层的平面展布;白云石化作用是优质储层形成的关键,为后期溶蚀提供了良好的条件;古岩溶是进一步增大孔隙,扩大储层范围的重要因素;裂缝改善了储层的储集和渗流性能。

The Carboniferous strata in the Fengjiawan Block in eastern Sichuan Basin have a large burial depth,a long time span,and various structural changes at different stages.A new round of seismic data has a new understanding of structure in the study area,and it is necessary to have a further deep study of the reservoir in the study area.Through the observation and analysis of core and thin sections,the results show that the rock types in the study area are diverse,and the main reservoir rocks are composed of different types of granular dolomites.The reservoir space is mainly composed of intergranular(dissolved)pores,intergranular(dissolved)pores and breccia/intercrystalline(intercrystalline)pores.The porosity is between 0.28% and 21.94%,and the average value is 4.63%,the permeability is between 0.001 and 39.60mD,with an average of 0.51mD,it is a low porosity and low permeability fracture-porosity reservoir,and the porosity and permeability show a good positive correlation;the reservoir development in the study area is controlled by sedimentary facies,rock types,dolomitization,paleokarst and structural fractures.The high-energy sedimentary environment of the granular dolomite provides a favorable material basis for reservoir development and controls the reservoir development on the plane.The dolomitization is the key to the formation of high-quality reservoirs,providing a good condition for later dissolution.Good conditions;the paleokarst is an important factor to further expand the range of reservoirs;the fractures further improve reservoir and seepage performance.