辽东湾地区断层演化特征及其对油气垂向富集的控制  

Fault evolution characteristics and its control on vertical enrichment of oil and gas in Liaodong Bay area

作　　者：兰蕾 杨树春 LAN Lei;YANG Shuchun(CNOOC Research Institute Ltd.,Beijing100028,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028

出　　处：《中国海上油气》2021年第4期14-21,共8页China Offshore Oil and Gas

基　　金：中海石油(中国)有限公司科技项目“中国近海盆地潜在富油凹陷资源潜力、成藏机制与突破方向(编号:YXKY-ZX01-2021)”部分研究成果。

摘　　要：地质历史时期的断层活动强度直接影响着油气运移,而目前仅依据断层晚期活动速率判断其输导性。本文以辽东湾地区为靶区,利用地层回剥技术刻画了该地区断层演化过程,并分析了断层演化特征对油气运移的影响。研究表明,辽东湾地区断层演化特征控制了原油的垂向分布,且15 m/Ma是该地区油气能否垂向运移的断层活动速率阈值。以断层活动速率15 m/Ma为断层活动强弱的判别标准,以东一段沉积期、馆陶组沉积期和明化镇组至今沉积期为时间阶段,该地区断层演化特征可划分为“强→弱→强”“强→弱→弱”和“弱→弱→弱”等3种模式,其中在“强→弱→强”和“强→弱→弱”模式下原油可运移至东营组或浅层馆陶组—明化镇组成藏,而在“弱→弱→弱”模式下原油则更可能充注在沙河街组烃源岩层系内。在这种认识的指导下,从常规油气勘探的角度来看,沙河街组是辽西凹陷最有利的勘探层系,在断层活动较强区域内距离生烃中心较近的东营组有效圈闭也可能是有利的勘探目标。The intensity of fault activity during geologic history directly controls the migration of oil and gas,the intensity of fault activity during geologic history directly controls the migration of oil and gas,yet the judgment of fault connectivity at present is only by the rate of fault activity at its late stage.This paper takes Liaodong Bay area as the target area,depicts the fault evolution process by back-stripping of stratum thickness technology and analyzes the influence of fault evolution characteristics on oil and gas migration.Studies show that the vertical distribution of crude oil is controlled by the characteristics of fault evolution in Liaodong Bay area,of which15 m/Ma is the threshold of fault activity rate for vertical migration of oil and gas.We take the fault activity rate of 15 m/Ma as the criterion for determining the intensity of fault activity,and the depositional period of the first member of Dongying Formation,the Guantao Formation and the Minghuazhen Formation to date as the geological time stages,the fault evolution characteristics in this area can be divided into three patterns,i.e.,“strong→weak→strong”,“strong→weak→weak”and“weak→weak→weak”.Among them,the oil and gas migrate to the Dongying Formation or the shallow Guantao—Minghuazhen Formation to accumulate there under the patterns of“strong→weak→strong”and“strong→weak→weak”,while under the pattern of“weak→weak→weak”the oil and gas are more likely to be retained in the source rock of the Shahejie Formation.Guided by this understanding,from the perspective of conventional oil and gas exploration,it is believed that the Shahejie Formation is the most favorable exploration formation in Liaoxi sag,and the effective trap of the Dongying Formation close to the hydrocarbon generation center in the area of strong fault activity may also be a favorable exploration target.

关 键 词：辽东湾地区 断层演化 活动速率 油气运移 辽西凹陷 有利勘探层系 

分 类 号：TE121.3[石油与天然气工程—油气勘探]