西非加蓬盆地深水区复杂盐下圈闭落实关键技术探索与实践

KEY TECHNOLOGY FOR EXPLORATION OF COMPLEX PRESALT TRAPS IN THE DEEP WATERS OF GABON BASIN, WEST AFRICA

近年来,以西非、墨西哥湾等为代表的全球深水盐下油气勘探日趋活跃,而构造落实一直是盐下勘探面临的主要难题,亟需形成一套有效的盐下圈闭落实技术方法。以加蓬某区为研究靶区,基于盐下地震成像特点,剖析盐下圈闭落实难点,再从盐岩形变机制分析入手,探索形成了一套复杂盐下圈闭落实关键技术组合,主要包括:①基于盐岩形变机制建立构造解释模型;②以脏盐体精细识别技术为核心的盐下层位解释技术;③利用重-磁-震资料联合,开展盐下断裂多尺度综合解释;④基于波动方程正演的构造假象识别技术。通过实践应用,在研究区内有效落实多个盐下圈闭,其中的M圈闭钻探证实为盐下大气田。形成的技术体系能够辅助解决盐下构造落实难题,可为西非及其他区域类似问题提供参考。

In recent years, global deepwater oil and gas exploration, as demonstrated by West Africa and the Gulf of Mexico, has become increasingly active. Verification of structures is always the key problem in salt basin exploration. Therefore, it really is a great need to develop a set of technology for trap identification to support the exploration of oil and gas under salt cap in the deep water of Gabon Basin. Based on the studies of the mechanisms of salt rock deformation and its impacts on seismic imaging, a set of key technology is proposed in this paper. It includes: ①Establishment of interpretation models for structures based on the mechanism of salt rock deformation;②Introducing the technique for pre-salt seismic horizon interpretation based on the fine recognition of dirty salt bodies;③Integration of gravity, magnetic and seismic data for multiscale comprehensive interpretation of pre-salt faults;④Adoption of the method for distinguishing false images from the real based on wave equation forward modeling. Using the method, a series of pre-salt traps are effectively identified in the research area, and drilling proves that the M trap is a large pre-salt gas field. It is concluded that the technical system proposed can help solve the problem of the verification of pre-salt structures, which can be used as a reference for similar oil fields in West Africa and other regions.