苏北盆地溱潼凹陷西斜坡剥蚀线识别技术

Identification technology of denudation line on the west slope of Qintong sag in Subei basin

溱潼凹陷位于苏北盆地东台凹陷东部,溱潼凹陷西斜坡阜宁组三段主要发育三角洲前缘沉积,储层发育薄层砂泥岩互层、横向变化快,阜宁组向外斜坡方向逐渐被剥蚀,发育剥蚀线遮挡型地层油藏,但剥蚀区的阜三段地震反射强度弱,地震数据很难准确刻画剥蚀线位置。通过正演揭示地震波阻消失点并不代表地层剥蚀点,需一定量外延,再利用定量回归确定剥蚀量与地层倾角的拟合关系,从而准确刻画剥蚀线位置,剥蚀线整体外延30~80 m,最终刻画剥蚀线遮挡型地层圈闭。

Qintong sag is located in the east of Dongtai sag in Subei Basin.The third member(Fu-3)of Funing formation in the west slope of Qintong sag mainly develops delta front deposits,with developed thin layers of sand-mudstone interbeds and a rapid horizontal variation.Funing formation is gradually denuded toward the outer slope,and developed denudation line-shielded stratigraphic reservoirs.However,the seismic reflection intensity of Fu-3 member in denudation area is weak,so it is difficult for seismic data to accurately describe the position of denudation line.Through forward simulation,it is revealed that the vanishing point of seismic wave resistance does not represent the denudation point of the stratum.A certain amount of extension is required,and then the quantitative regression is used to determine the fitting relationship between the denudation amount and the stratum dip angle,so as to accurately depict the position of the denudation line.The overall extension of the denudation line is 30~80 m,and the denudation line sheltered stratigraphic trap is finally depicted.