地质地球物理综合解释技术在六盘山盆地的应用

Application of Comprehensive Geological and Geophysical Interpretation Technology in Liupanshan Basin

六盘山盆地属于典型的黄土塬地貌沉积盆地,地表条件及地下地质情况复杂,导致二维地震资料信噪比低、静校正难度大、资料品质较差、物探综合解释难度大。综合利用地震合成记录、井正演及野外露头开展地层多元综合标定,明确探区内各组系地层顶底反射界面及其地震反射特征;结合野外构造形迹调查,利用重电震联合约束反演进行相互验证,建立了走滑冲断构造解释模型;通过精细速度分析,建立了研究区速度场,运用模型层析变速成图技术准确落实地下构造。在地质与地球物理技术综合应用基础上,预测有利烃源岩展布区带,部署马参1井。该井钻遇了与预测较为吻合的泥岩及暗色泥岩,并在下白垩统李洼峡组见到了良好的油气显示,证实六盘山盆地西南部确实存在成烃成藏的过程,盆地内马东山构造带是下步勘探的重点区带。

Liupanshan basin is a typical loess plateau geomorphic sedimentary basin. The complex surface conditions and underground geological conditions lead to low signal-to-noise ratio of two-dimensional seismic data,great difficulty in static correction,poor data quality,and great difficulty in comprehensive geophysical interpretation.The seismic synthetic records,well forward modeling and field outcrop were used to carry out multivariate comprehensive stratigraphic calibration,and the top and bottom reflection interfaces and seismic reflection characteristics of each formation in the exploration area are clearly defined. At the same time,Combining with the field structural trace investigation and using the combined constrained inversion of gravity,electricity and earthquake to verify each other,the interpretation model of strike-slip thrust structure was established. Through the fine velocity analysis,the velocity field in the study area was established,and the underground structure was accurately implemented by using model tomography variable speed mapping technology. On the basis of comprehensive application of geology and geophysical technology,the distribution zone of favorable source rocks was predicted,and well Macan 1 was deployed. The well encountered mudstones and dark mudstones which were in good agreement with the prediction.Good oil and gas shows were found in the Liwaxia formation of the lower Cretaceous,which confirmed the existence of hydrocarbon accumulation process in the southwestern part of Liupanshan basin. The Madongshan structural belt in the basin is the key area for further exploration.