齐家地区高Ⅲ、高Ⅳ组砂岩输导层静态连通评价

Static connectivity evaluation of sandstone carrier bed in GⅢ-GⅣ groups in Qijia area

针对松辽盆地齐家地区高Ⅲ、高Ⅳ组三角洲前缘亚相砂体静态连通性定量评价的难题,综合岩心、测井和地震等资料,采用渗逾理论指导和油藏解剖验证开展砂体静态连通性定量评价。结果表明:高Ⅲ、高Ⅳ组垂向上可划分为5套单一砂岩输导层(S1—S5),受湖侵泥岩隔板遮挡影响,各单一砂岩输导层内含油砂岩比例自上而下逐渐减小;基于沉积环境差异,分别厘定出三角洲内、外前缘亚相砂体连通的渗流阈值C0(10%,5%)和完全连通系数C(60%,50%),且砂体连通概率随砂地比增大而增加;受物源供给和沉积演化影响,5套单一砂岩输导层自南向北和自下而上连通性逐渐变好,油气平面上主要分布在砂体连通概率快速增长的砂地比值30%~50%的有利区带。

Aiming at the problem of quantitative evaluation of static connectivity of delta front subfacies sandbodies in GⅢ-GⅣgroups in Qijia area of Songliao Basin,the core,logging and seismic data were used to quantitatively evaluate the static connectivity of sandbodies by using infiltration theory guidance and reservoir anatomy verification.The results show that the GⅢ-GⅣgroups are vertically divided into five sets of single sandstone carrier beds(S1-S5).Reservoir anatomy indicates that the proportion of oil-bearing sandstone in each single sandstone transport layer is gradually reduced from top to bottom due to the blockage of lake instrusive mudstone.Based on the differences in sedimentary environment,the initial connected net-to-gross threshold ratios C0(10%and 5%)and fully-connected net-to-gross ratio thresholds C(60%and 50%)were determined for the single carrier bed in the inner and outer frontal deltas,and the connectivity probability increases with the increase of net-to-gross ratio.Affected by source supply and sedimentary evolution,the five sets of single carrier beds gradually become better from south to north and from bottom to top,and the oil and gas are mainly distributed horizontally in the favorable zone with a rapid net-to-gross growth of sandbody connectivity probability of 30%-50%.