论文详情
近年来, 光纤传感技术已经应用于地面地震数据、海洋地震数据、井中地震数据和井-地联合地震数据的采集, 推动了光纤传感技术在地球物理特别是地震数据采集中的应用。井-地或井-海联合地震勘探是陆地或海洋三维地震与三维DAS-VSP勘探相结合形成的三维立体地震勘探方法, 利用井-海联采的三维DAS-VSP数据, 可以获得地下井周围准确的时深关系、地层速度、反褶积算子、球面扩散补偿因子、吸收衰减因子、各向异性参数和井筒周围的高分辨率构造成像, 这些参数可以基于井驱处理提高陆地或海洋三维地震数据的处理质量。在中国东海某OBN数据勘探中首次开展了井下套管内铠装光缆同步采集的三维DAS-VSP数据的处理方法研究以及成像处理。首先, 采用常规的三维VSP数据成像处理技术对三维DAS-VSP数据进行常规处理, 具体处理流程包括: 观测系统定义、预处理、初至拾取、静校正、振幅补偿、反褶积、波场分离、速度分析与建模和利用上行反射波进行井周围地层的构造成像; 然后, 再根据海上三维DAS-VSP数据下行多次波的特点, 研发了海上三维DAS-VSP数据的下行多次波成像技术, 扩展了三维DAS-VSP数据成像范围, 提高了三维DAS-VSP数据成像的整体质量。与本工区早期的三维OBC数据成像结果相比, 本次三维DAS-VSP数据的下行多次波成像结果表明, 井周围三维构造成像质量得到了显著改进, 大幅度扩展了成像范围; 新采集的OBN数据和三维DAS-VSP数据的成像结果展示了更为详细和较高分辨率的构造成像, 基于新的成像资料, 对储层顶部和储层内流体的识别与追踪变得更加容易和清晰。井-海联采技术生产效率高且成本低, 既能快速获得三维DAS-VSP数据及成像, 还能对三维海洋地震数据进行井驱提高分辨率处理。此外, 三维OBN或OBC数据和三维DAS-VSP数据还能够进行融合处理, 实现井-地或井-海同步采集数据的联合偏移成像, 可以大幅度提高三维海洋地震数据的成像品质, 值得在有条件的地方推广应用。
Optical fiber sensing has been applied to surface, marine, and borehole seismic acquisition and joint borehole-surface seismic acquisition in the latest years. Surface or marine seismic and VSP seismic exploration could be combined to achieve 3D prospecting. Using 3D DAS-VSP data, we could obtain accurate time-depth relationship, interval velocity, deconvolution operator, compensation factor of spherical spreading, absorption attenuation factor, anisotropy parameters, and high-resolution structure imaging around the well bore; above parameters could be used to enhance 3D well-driven land or marine seismic data processing. In this work we performed 3D DAS-VSP data processing and imaging. The 3D DAS-VSP survey was acquired using a downhole armored optical cable with simultaneous OBN data acquisition in the East China Sea. The routine workflow of 3D DAS-VSP data processing includes geometry definition, preprocessing, first break picking, static correction, amplitude compensation, deconvolution, wave field separation, velocity analysis and modeling, and structure imaging using upgoing waves. A new technique of downgoing multiple reflection imaging is developed to enlarge the migration aperture and imaging area of upgoing reflected waves and obtain better quality of imaging. Compared with 3D vintage OBC data imaging, 3D DAS-VSP downgoing multiple imaging yields better results within a large area around the well bore; OBN and 3D DAS-VSP imaging yields better results for high-resolution structure interpretation and fluid detection. Owing to high efficiency and low cost of joint borehole-marine acquisition, it is possible to accomplish fast 3D DAS-VSP imaging and enhanced well-driven resolution processing of 3D marine seismic data. Besides, 3D OBN or OBC data and 3D DAS-VSP data could be processed together for joint borehole-surface or borehole-marine migration to significantly improve the imaging quality of 3D marine seismic data.