柴达木盆地英中地区下干柴沟组盐间复杂断裂识别  

Identification of complex intersalt faults in lower Ganchaigou Formation,Yingzhong area,Qaidam Basin

作　　者：丁博钊 杨静 万学娟 马宁 秦川 滕越 DING Bozhao;YANG Jing;WAN Xuejuan;MA Ning;QIN Chuan;TENG Yue(Geophysical Research Institute,BGP Inc.,CNPC,Zhuozhou,Hebei 072751,China)

机构地区：[1]东方地球物理公司研究院,河北涿州072751

出　　处：《石油地球物理勘探》2024年第5期1155-1164,共10页Oil Geophysical Prospecting

基　　金：中国石油集团公司科研项目“盐穴储库复杂介质地震响应规律及表征方法”(2023DJ8307)资助。

摘　　要：柴达木盆地英中地区地表及地下地质条件复杂,基于常规叠前深度偏移资料难以准确刻画下干柴沟组盐间断裂系统。基于多方位网格层析速度优化后的叠前深度偏移资料能够对下干柴沟组盐间复杂断裂进行准确识别,结合分方位倾角扫描属性分析,厘清断裂体系的平面展布特征,为英中地区有利区带划分和优选提供了依据。结果表明:①基于多方位网格层析速度优化后的叠前深度偏移资料较好地解决了英中地区下干柴沟组地层产状成像不准、断裂成像不清的问题,通过对新处理地震资料重新解释,发现在XI号断裂和IV号断裂相交形成的“夹角区”内,下干柴沟组盐间地层存在多个小型滑脱断层,与盐下地层发育的叠瓦冲断断裂分属不同断裂体系;②基于新的叠前深度偏移资料提取分方位倾角扫描属性,揭示盐间小型滑脱断层在平面上呈反“S”形展布,与北北东向的区域挤压构造应力背景吻合,发育时期为上新世晚期—第四纪强烈挤压定型阶段;③下干柴沟组盐间断裂对局部构造控制作用明显,目前在“夹角区”内识别了六个有利圈闭,部分井已获得高产,是下一步勘探的重点有利区带。The surface and underground geological conditions in the Yingzhong area of Qaidam basin are com plex,making it difficult to precisely delineate the intersalt faults in the Lower Ganchaigou Formation with conventional data of prestack depth migration.This study utilizes optimized prestack depth migration data based on multi-directional grid tomography to accurately identify the complex faults in that area.The distribution characteristics of the complex intersalt fault system are also studied with attribute analysis using azimuthal dip scanning.This study provides a basis for the delineation and selection of favorable zones in the Yingzhong area.The results are as follows.①The optimized prestack depth migration data based on multi-directional grid tomography solves the problems of inaccurate occurrence imaging and unclear fault imaging of the lower Ganchaigou Formation in the Yingzhong area.The reinterpretation of the new seismic data reveals that in the“included angle area”formed by the intersection of Fault XI and Fault IV,there are several small detachment faults in the inter salt strata of the lower Ganchaigou Formation,which belong to different fault systems compared to the imbricate thrust faults developed in the sub-salt strata.②Based on the new prestack depth migration data,the azimuthal dip scanning attributes are extracted,which reveals that these small inter salt detachment faults are distributed in an inverse“S”shape in the map.This is consistent with the regional compressive tectonic stress in the NNE direction,indicating that they are formed during the intense compression and stabilization stage from the late Pliocene to the Quaternary.③The intersalt faults in the lower Ganchaigou Formation have strong control over local structures.Six favorable traps are identified in the“included angle area”and several wells are very productive,indicating that the intersalt faults are key favorable zones for future exploration.

关 键 词：复杂盐间断裂系统 滑脱构造 多方位网格层析成像技术 分方位倾角扫描 柴达木盆地 英中地区 

分 类 号：P631[天文地球—地质矿产勘探]