复杂沉积区的岩性预测技术及其在银额盆地哈日凹陷的应用

Lithology prediction technology in complicated sedimentary area and its application in Hari Sag,Yin'e Basin

目的以现代油气勘探理论为指导,运用测井和地震联合反演方法,预测银额盆地复杂沉积区的岩性。方法采用不同岩性具有不同的地球物理特征选取岩性预测参数、根据既具备自然伽马、补偿中子的高频信息,又包含声波的低频信息的拟声波曲线耦合地震数据有效区分砂岩、泥岩和白云岩,利用层位标定和子波反演的交互迭代运算,建立集地质、测井、地震的地质框架,再利用一定的插值方法对层内的测井数据进行内插和外推,进而建立波阻抗模型。结果(1)白云岩主要在银根组,分布较为广泛;(2)砂岩发育层系较多,在苏红图组、巴音戈壁组均较为发育,主要以陡坡带上的扇三角洲和冲积扇为主;(3)灰质泥岩主要分布在断陷的中央深凹带,以巴音戈壁组最为发育;(4)火山岩分布较为局限,仅在哈日凹陷发现,且受断裂控制,沿断裂展布。结论全局寻优迭代的岩性预测技术地质意义明确,可以准确表征不同岩性,精细预测岩性分布,适用于复杂沉积区的岩性预测。

Purposes—To predict lithology of mixed sedimentary area by using modern oil and gas exploration theory,logging and seismic joint inversion method in Yin'e basin.Methods—Different lithology with different geophysical characteristics is used to select lithology prediction parameters.Sandstone,mudstone and dolomite were effectively distinguished according to the pseudo acoustic curve coupling seismic data with both high frequency information of natural gamma,compensated neutron and low frequency information of acoustic wave.A set of geological framework based on geological,logging and seismic data was established with the interactive iterative operation of horizon calibration and wavelet inversion,and then the wave impedance model was established by interpolating and extrapolating the logging data in the formation with some interpolation methods.Result—(1)Dolostone is mainly distributed in the Yin gen formation;(2)The sandstone is well developed in many strata,such as Suhongtu formation and Bayingobi formation,which is mainly fan delta and alluvial fan on steep slope belt;(3)Calcareous clay is mainly distributed in the central depression of the fault depression,and the Bayingobi formation is the most developed;(4)The distribution of volcanic rocks is limited,which is only found in Hari sag,controlled by faults and distributed along faults.Conclusion—The lithology prediction technology of global optimization iteration not only has clear geological significance but also can accurately characterize different lithology and predict lithology distribution,so it is suitable for lithology prediction in mixed sedimentary area.