深拖平缆双方位地震资料联合成像技术在古近系复杂构造区的应用  

Application of a joint imaging technique entailing dual-azimuth seismic data acquired by deeper-towing flat-streamers on complex structures of the Paleogene

作　　者：肖张波 张素芳 雷永昌 孙阳子 贾连凯 佘清华 XIAO Zhangbo;ZHANG Sufang;LEI Yongchang;SUN Yangzi;JIA Liankai;SHE Qinghua(Shenzhen Branch of CNOOC China Limited,Shenzhen 518000,China)

机构地区：[1]中海石油(中国)有限公司深圳分公司,广东深圳518000

出　　处：《石油物探》2021年第6期971-982,共12页Geophysical Prospecting For Petroleum

基　　金：国家科技重大专项“南海东部海域勘探新领域及关键技术”(2016ZX05024-004);“南海东部油田上产2000万吨关键技术研究”(CNOOC-KJ135ZDXM37SZ)共同资助。

摘　　要：陆丰南古近系地层地质条件复杂,断裂活动强烈,地层接触关系复杂,解释难度大。常规窄方位采集数据的不足,导致中深层地层的反射能量弱、信噪比低、连续性差,完全依赖重处理已无法满足当前复杂目标评价的需求,如何改善古近系中深层地层的成像是目前勘探的关键。首次在南海东部针对古近系地层采用深拖平缆双方位地震勘探,对比分析深沉放双方位三维与常规三维地震的采集参数,明确了深拖平缆双方位资料具有丰富的低频信号及照明优势。采用双方位联合速度建模及双方位TTI各向异性叠前深度偏移联合成像,解决双方位速度差异问题,提高速度建模精度,实现了双方位三维地震资料的融合处理。资料成果表明,新资料低频端信息更丰富,深层断面成像更加清晰,断裂样式和交切关系更可靠;地层接触关系及砂体边界刻画改善明显。勘探实践证实:深拖平缆双方位地震资料联合成像技术有效改善了古近系复杂构造的成像,在精细评价中具有较好的适用性,推动了该区的勘探研究进程。The geological conditions of Paleogene strata in the Lufeng South area are quite complex owing to the intense fault activity and the complex contact relationships among the strata.Therefore,achieving a seismic interpretation is quite difficult.Seismic data acquired by conventional narrow-azimuth acquisitions are insufficient:they result in low reflection energy,low signal-to-noise ratios,and low continuity in mid-depth strata.Therefore,the increasing demand for prospect evaluation cannot be met by simply relying on seismic reprocessing.Clearly,improving the imaging of mid-depth strata has become crucial for petroleum exploration in the study area.In this work,a deeper-towing flat-streamer dual-azimuth seismic acquisition method was applied for the first time to an area in the eastern portion of the South China Sea.Compared with conventional acquisition parameters,the proposed method significantly enhances both the energy of low-frequency signals and the seismic illumination.Pre-stack depth migration joint imaging using a dual-azimuth joint velocity or a dual-azimuth tilted transversely isotropic anisotropic velocity field can improve the accuracy of velocity modeling.In doing so,it can effectively achieve simultaneous processing of dual-azimuth three-dimensional seismic data.These data provide richer low-frequency information,clearer fault imaging in deep strata,a more reliable interpretation of fault patterns and intersection relationships,and clearer contact relationships among strata.Furthermore,these data are advantageous for the description of sand bodies.Exploration practice has demonstrated that the joint imaging of deeper-towing flat-streamers dual-azimuth seismic data can effectively improve the imaging of complex structures of the Paleogene.As such,the proposed method has good applicability in prospect evaluation,thereby promoting the exploration and research progress in this area.

关 键 词：古近系 深沉放 双方位 联合成像 各向异性 复杂断裂 地层岩性圈闭 

分 类 号：P631[天文地球—地质矿产勘探]