辽东湾盆地辽中凹陷隐蔽油气藏成藏模拟

利用辽东湾盆地辽中凹陷高精度层序地层研究的结果,构建了包含隐蔽砂体的精细沉积剖面,并使用法国石油研究院的Temis2D软件对隐蔽油气藏成藏进行了模拟,模拟的结果和实际钻探情况一致.模拟结果表明:辽东湾盆地辽中凹陷沙河街组透镜体隐蔽油气藏以初次运移为主,地层油气藏靠储集体以侧向二次运移为主,沙河街组隐蔽油气藏形成较早,大概于东营组沉积末期至馆陶组沉积初期最终成藏,但远离生烃中心的隐蔽油气藏由于运移距离较长其成藏定型时间有一定的延迟;东营组隐蔽油气藏以断层作为主要的输导通道以二次运移为主,也有借助于微裂缝或者靠超压突破盖层压力以初次运移为主,东营组隐蔽油气藏成藏较晚,于新近纪明化镇组沉积时期(12 Ma)开始成藏,而远离生烃中心的隐蔽油气藏甚至于6 Ma以后才开始成藏.隐蔽油气藏形成与输导体系、侧封和顶封密切相关,如果输导通道的输导性能过强而封堵性差,油气可能漏失.

THE SUBTLE RESERVOIR FORMING MODELING IN THE LIAOZHONG SAG, THE LIAODONG BAY BASIN

The research results of high precision sequence stratigraphy in the Liaozhong Sag of the Liaodong Bay Basin are used to build up detailed sedimentary sections that can exhibit the subtle sandbodies,and Temis2D software of IFP is employed to model the subtle reservoirs forming process for the first time.The results indicate that the modeling outcome is consistent with the drilling activities,which shows the subtle reservoir modeling is feasible.The modeling results reveal: the subtle lens reservoirs in Shahejie Fm in the Liaodong Sag of the Liaodong Bay Basin were formed by primary migration while the stratigraphic reservoirs were formed by secondary migration;the forming time of the subtle reservoirs in Shahejie Fm is relatively earlier than that in Dongying Fm;subtle reservoirs in Shahejie Fm were mainly formed at the final stage of Dongying and early stage of Guantao,but the forming time of some subtle reservoirs far away from the hydrocarbon kitchen were delayed due to the long distance migration.The subtle reservoirs in Dongying Fm were formed by the conduits of fault pathways and secondary migration,some were formed by the conduits of micro-crack or primary migration with the result of overpressure surpassing the seal pressure.The subtle reservoirs within Dongying Fm were formed later than those within Shahejie Fm,most were formed at the time of about 12 Ma,but some far away from the hydrocarbon kitchen were even formed after 6 Ma.Moreover,the forming of subtle reservoirs in this basin is related to the pathway system,lateral seal and top seal,the oil and gas would leak under the conditions of the open conduit and poor seal characteristics.