基于大型低频可控震源的超深储层广角反射采集技术

随着超深储层的油气勘探力度不断加大,针对复杂的表层结构和地下地质构造地区,常规地震勘探方法难以获取信噪比较高的有效反射信息,地震资料成像效果差,地震剖面难以清楚刻画工区的地质构造。因此,基于大型低频可控震源激发技术,根据野外采集要求,结合地质任务,选择采用高密度二维广角反射地震观测系统进行地震资料采集,通过广角地震波数值模拟和野外试验工作,优选出适合本工区的野外采集参数。研究结果表明,基于大型低频可控震源的超深储层广角反射采集技术,能够获得较强能量的远偏移距处的弱反射地震信号,特别是深层的低频信息,有效地提高了地震资料信噪比。相对于常规地震叠加剖面,广角反射地震叠加剖面品质得到明显改善,同相轴连续,构造部位清晰可见,地震成像效果良好。野外生产实践证明,广角反射地震勘探技术对超深层油气勘探具有重要的应用价值。

Wide-angle reflection acquisition technology for ultradeep reservoirs based on large-scale low-frequency vibroseis

With the intensification of hydrocarbon exploration in ultradeep reservoirs, conventional seismic exploration methods are no longer applicable to areas with complex surface structures and underground geological structures because they are difficult to acquire effective reflection information with high signal-to-noise ratio, the imaging effects of seismic data are poor, seismic profiles fail to clearly present the geological structures of study areas. Based on the large-scale low-frequency vibroseis excitation technology, the field acquisition requirements, and geological tasks, this study adopted a high-density two-dimensional wide-angle reflection seismic observation system to collect seismic data. This study selected the optimal field acquisition parameters suitable for the study area through numerical simulation of wide-angle seismic waves and field tests. As indicated by the results of this study, the wide-angle reflection acquisition technology for ultradeep reservoirs based on large-scale low-frequency vibroseis can acquire weakly reflected seismic signals at locations with far offset and strong energy, especially the deep low-frequency information, thus effectively improving the signal-to-noise ratio of seismic data. Compared with conventional seismic stacked sections, the wide-angle reflection seismic stacked sections have significantly improved quality, continuous events, clearly visible structural parts, and encouraging seismic imaging effects. The field production practices dominate that the wide-angle reflection seismic exploration technology can be applied to ultradeep hydrocarbon exploration.