四川盆地磨溪地区震旦系灯影组四段储层特征及勘探启示

Reservoir characteristics of the fourth member of Sinian Dengying Formation and its implications for oil and gas exploration in Moxi area,Sichuan Basin

综合岩心、薄片、成像测井等资料,在高精度层序地层划分及沉积相研究的基础上,对四川盆地磨溪地区震旦系灯影组四段的台缘丘、台缘丘后滩及局限台地等相带储层特征进行了描述和对比。研究结果表明:(1)磨溪地区灯影组四段可划分出2个三级层序、7个准层序组和13个准层序。(2)研究区台地边缘带可划分出台缘丘、台缘滩、丘(滩)间等亚相,在局限台地内部识别出了台内丘、台内滩、丘(滩)间、潟湖和局限潮下等亚相,并细分了微相类型。(3)台缘区与台内区的储集岩石类型、储集空间及储集类型等基本一致,受三级层序高位体系域控制,垂向上发育2套储层,低角度和高角度微裂缝密度垂向上差异较大,物性具有向上变好的趋势。(4)不同相带储层孔隙空间类型及储层物性存在差异,台缘微生物丘发育区储层物性好,微裂缝和孔洞发育好,台缘丘后滩发育区微裂缝和孔隙发育程度及储层物性均变差,台内区进一步变差,但远离台缘区的局限台地区仍发育良好储层。

Based on the high-precision sequence stratigraphic division and sedimentary facies research,the reservoir characteristics of the platform-margin mound,the back shoal of platform-margin mound and the restricted platform of the fourth member of Sinian Dengying Formation in Moxi area,Sichuan Basin were characterized and compared by using the data of cores,thin sections and imaging logging.The results show that:(1)The fourth member of Dengying Formation in Moxi area can be divided into two third-order sequences,seven parasequence sets and 13 parasequence.(2)Platform-margin mound,platform-margin shoal,inter-mound and shoal were recognized in platform-margin,and restricted platform were divided into inner mound,inner shoal,inter mound,lagoons and restricted subtidal subfacies,then the microfacies were divided further.(3)The reservoir rock type,reservoir space and reservoir type of platform-margin zone and intra-platform area are basically the same and controlled by the highstand systems tract.Two sets of reservoirs are developed vertically,low angle and high angle microfractures are differently developed vertically,and physical properties tend to improve upward.(4)The reservoir space types and physical properties in different facies zones are different.The platform-margin microbial mound has the characteristics of good reservoir physical properties,with microfractures and pores well developed.The development degree of microfractures and pores and physical properties in the development area of back shoal of platform-margin mound is weakened,and it is further weakened in the intra-platform zones.However,there are good reservoirs developed in the restricted platform far from the platform-margin zones.