论文详情
相较于拖缆地震数据, OBN地震数据品质较高, 但OBN地震采集施工复杂、费用高昂, 因此有必要厘清拖缆地震数据和OBN地震数据在成像质量以及构造和储层的刻画能力, 了解OBN地震数据的相对优势, 进而指导油气勘探、开发地震数据的优选。深入对比了针对深水盐下目标的OBN地震数据和拖缆地震数据: 首先根据二者观测方式的特点, 对比分析二者在偏移距、方位范围、照明度、信噪比和地震速度场方面的差异; 然后针对复杂盐下地层成像难的特点, 全面分析了两种数据的绕射波成像、断层成像、基底成像、纵横向分辨率等数据特征以及构造深度、地震反演等解释结果特征; 最后针对OBN地震数据低频信号丰富的特点, 通过测井数据滤波分析了丰富的低频信号对地质体轮廓刻画的作用, 并提出了利用统计子波计算地震分辨率的方法。研究发现相较于拖缆地震, OBN地震作为大偏移距、宽方位的采集方式, 使得其地震照明度更好和速度场精度更高, OBN地震数据品质更好; 拖缆地震数据和OBN地震数据在盐下的构造形态和地震反演趋势大体一致, 但OBN地震数据在构造和储层细节刻画上优势明显。OBN地震数据具有成像效果佳、断层反射清楚、基底响应清晰、地震分辨率高、地震频带宽且低频信号丰富、构造深度误差小、地震反演细节多等优点, 研究结果可为同类型油田研究和应用拖缆地震和OBN地震提供较高的参考价值。
OBN data have better quality than streamer data, but OBN acquisition is complicated and expensive. Thus, it is necessary to perform a detailed assessment of OBN and streamer data from the perspectives of imaging and structure and reservoir characterization as well as OBN comparative advantages for hydrocarbon exploration and development. The case study deals with deep-water sub-salt formations. We first examine the discrepancies between OBN and streamer data in offset, azimuth, illumination, signal-to-noise ratio, and seismic velocity field in accordance with their different geometries. In view of the challenges in complicated sub-salt formation imaging, the comprehensive analysis involves diffracted-wave imaging, fault imaging, basement imaging, and vertical and lateral resolutions of these two data types and their interpretation results of structure depth and inversion. With respect to abundant low frequencies in OBN data, we use filtered log data to investigate their contribution to the characterization of geologic boundaries and propose a method of resolution calculation using statistical wavelet. Compared with streamer data, OBN data show better quality owing to large-offset wide-azimuth acquisition and consequent better illumination and more accurate velocity field. Similar sub-salt structural features and trends of inversion results could be obtained using streamer and OBN data, but the latter performs better in detailed structure and reservoir characterization. In summary, OBN data feature better imaging, more distinct fault and basement reflections, higher resolution, wider band, more abundant low frequencies, smaller error of structure depth, and more detailed inversion results compared with streamer data. Research results may be used for reference in the study of streamer and OBN data in other oilfields.