松辽盆地北部他拉哈-齐家地区姚一段沉积与成藏特征再认识

Re-explanation for Deposition and Reservoir Characteristics of the First Member of Yaojia Formation in Talaha-Qijia Area of Songliao Basin

综合20口井岩心和496口井测井、录井及分析化验资料,对松辽盆地他拉哈-齐家地区姚一段葡萄花油层进行高分辨率层序地层研究,提出葡萄花油层北、西部为同沉积构造抬升控制的底部缺失的层序地层新格架。研究区最有利相带砂体为窄而细的末梢河道砂、薄层河口坝及席状砂体,而研究区北半部大量宽泛的厚层优质河道砂却不含油,为大面积含水区。研究总结发现,砂体发育与岩性油气藏分布均受控于一挠曲坡折带,坡折带以内为低水位体系域沉积质量中心,砂岩厚薄相间,可形成地层超覆圈闭;坡折带之下为3个层序低水位和水进体系域三角洲前缘砂体叠合区,发育的砂岩较薄且连通性差,是多层位岩性圈闭和上倾尖灭型圈闭发育区;坡折带之上以水进体系域平原相及前缘相的大量厚层河道砂体为主,但因连通性好,油气易散失,不易形成岩性圈闭,而成为大范围的含水区。坡折带"控层""控相""控砂""控藏"的理论在本研究区又一次得到极好的应用与验证。

By using the high-resolution sequence stratigraphy theory,through depositional dynamic analysis,the cores of 20 wells and 496 well logging data,Putaohua reservoir of the Talaha-Qijia area in Songliao Basin is divided as 1 long-term base level cycles,3 medium-term base level cycles,8 short-term base level cycles,proposed a new framework with the sedimentary structure lifting control the north and west of Putaohua reservoir.Fine study of sedimentary characteristics reveals that the most favorable facies sandbody is narrow submarine river sandbody,thin channel-mouth bar and sheet sanbody.In the northern half of the study area a large number of broad thick favorable submarine river sandbody is not oily but water-bearing zone.It is realized that sandbody development and distribution of lithologic reservoirs are controlled by a slope break.Area within slope break is the LST for the center of mass deposition,which is thick or thin layer of sandstone,and can form the stratigraphic overlapped traps.Area under the slope break is the delta front facies sandstone superimposed zone of LST and TST of 3 sequences with the development of thin sandstone and poor connectivity,and is a multi-layer lithologic trap development zone.Area above the slope break has a large number of plain and front facies thick channel sand body of TST.Its connectivity is good,so oil and gas are easily lost and difficult to form a lithologic trap.This area had become a large-scale water-bearing zone.All shows that ＂the slope break controls the distribution of stratum,facies,sands,traps and oil reservoirs＂ theory has once again been an excellent application and verification in the study area.