雅克拉断凸东段侏罗系-白垩系地层超覆圈闭预测

雅克拉断凸东段位于库车坳陷前缘斜坡带,侏罗系—白垩系向南超覆于前中生界凸起基底之上,形成了一系列地层超覆圈闭.由于大部分侏罗系—白垩系上超尖灭体不同程度地与前中生界区域性不整合(T50)下伏的不同地层接触,地层超覆圈闭的有效性受控于下伏地层的致密程度.利用地震属性、钻井资料和三维地震剖面相结合的方法对T50区域不整合下伏地层的分布、岩性和封堵性进行了分析,按封堵性将它们分为3种类型:下寒武统玉尔吐斯组—震旦系泥岩、泥质白云岩为封堵性底板,元古宇变质岩、中上寒武统白云岩和石炭系砂泥岩为可能封堵性底板,具溶蚀特征的中上寒武统白云岩和元古宇变质岩为渗透性储层底板.通过二维正演地质模型分析佐证了这3类不同封堵性能地层的地震识别特征.综合分析认为Jse3旋回、Kse1旋回以及Jse1旋回在DG2井附近可形成可观的、有效的地层超覆圈闭.

The Prediction of Jurassic-Cretaceous Stratigraphic Overlap Traps in the East Part of Yakela Fault Arch

The east part of Yakela fault arch is located in the frontal uplift of Kuqa Depression.Jurassic-Cretaceous formation southward onlapped the pre-Mesozoic uplift basement,formed a series of stratigraphic overlap traps.However,most of Jurassic-Cretaceous onlap units are related to different underlaying formations under the pre-Mesozoic regional unconformity T05 in different degree.Sealing property of the underlaying formations directly infleunces the effectiveness of traps.Based on seismic attributes,well calibration and 3-D seismic sections,the distribution,lithology and sealing property of underlaying formations under T05 unconformity are divided into three types.Mudstone and argillaceous dolomite from Lower Cambrian Yuertus Formation to Sinian are good sealing floors.Proterozoic metamorphic rock,Mid-Upper Cambrian dolomite,and Carboniferous sand-mudstone are possible sealing floors.Mid-Upper Cambrian karst dolomite and Proterozoic dissolved metamorphic rock are permeable reservoir floors.Model analysis further verifies the seismic identification characteristics of this three lithologies.It is concluded that Jse3,Kse1 and Jse1 cycle near DG2 are likely to form appreciable and effective stratigraphic overlap traps.