伊朗SA油田Kazhidumi油藏再认识

Review on the Characteristic of Kazhidumi Reservoir in SA Oilfield,Iran

针对伊朗SA油田Kazhidumi砂岩油藏油水关系复杂、无明显油水边界、油藏性质认识不清的问题,综合运用取芯、测井、三维地震资料及新钻井资料,对其油藏特征及形成机理进行研究。运用高分辨率层序地层学将地层划分为4个旋回,研究各旋回内砂体发育特征。运用地震层拉平技术对研究区不同地质时期古构造进行恢复,重现构造演化史;明确了油藏古构造圈闭形成于古近纪初期,为北高南低的单一背斜,新近纪扎格罗斯造山运动使得圈闭形态发生巨大改变,原古背斜圈闭面积缩小,高点向东部转移,南部地层大幅度上升隆起,形成新的构造高点,演变为现今南北两构造高点的格局。圈闭形态变化打破了古油藏平衡,使其发生了二次调整运移,北部构造高点(古圈闭)内油气发生自西向东运移,形成"缩小版"原地滞留油藏,部分油气自北向南运移,形成次生油藏。现今北部高点"上水下油"的现象,为油藏调整之后,底部K2-c旋回内连通性较差储层形成的滞留透镜状油、水层。油藏性质为构造控制为主,岩性控制为辅的层状边水油藏。

Considering the issues of the complex oil-water relationship,ambiguous oil-water contact and unclear reservoir characteristic of the Kazhidumi in SA Oilfield,southwest Iran.We study the Kazhidumi reservoir character and its formation mechanism by uitilizing the coring,well-logging and 3D seismic data.Firstly,Kazhidumi formation was divided into 4 zones by sequence stratigraphy,and recognize the sandbody features in different zones.Secondly,trap evolution history of Kazhidumi is displayed by layer flattening technique on 3D seismic data and mainly show as：paleo-trap of Kazhidumi is the giant anticline which situated in the north of current field area before the Zagoros orogeny.Impact by the Zagros orogeny,the paleo-trap shrink and the high point shifts to east,in the mean time,southern area was uplifting then forming a new secondary trap.Trap alteration breaks the paleo-reservoir equilibrium and cause the oil secondary migration.In the northern high point（paleo-trap）,the oil migrates from west to east then form the ＂sacled-down version＂ retention reservoir,while some part migrate to southern secondary trap and form the new reservoir.The phenomenon of ＂upper water and bottom oil＂ in the current northern high point is the lensing retention oil and water layer after secondary migration.Kazhidumi reservoir is the layer reservoir with edge water and mainly controlled by the structure.According to the new recognition,we propose the corresponding development suggestions.