虚拟震源方法用于探测地下陡倾角地质构造

摘要

当常规地震勘探数据处理方法不能对地下存在的陡倾角地质构造获得满意的成像效果时,应用虚拟震源方法将垂直地震剖面(VSP,vertical seismic profile)数据重构成单井剖面(SWP,single well profile)数据,可以使得观测系统重构到更接近于井附近目标体的位置,震源和检波器都位于复杂的覆盖之下并避免井和地表之间未知速度信息的影响,从而获得对地下地质构造更好的成像分辨率.尤其是当地下存在诸如断层这样的陡倾角地质构造时,虚拟震源方法可以对目标体产生很好的成像效果.本文进行了声波数据和弹性波数据的模拟实验,将模型中的陡构造设置为断层,测试虚拟震源方法用于探测地下陡倾角地质构造的能力,对声波和弹性波介质都获得了满意的成像结果；在应用稀疏观测系统进行测量时,仍然可以得到较好的成像效果.%When the conventional seismic data processing methods failed to acquire the satisfactory imaging results of subsurface steep structure, the virtual source method should be applied to convert the traditional vertical seismic profile (VSP, vertical seismic prodile) gathers into virtual single well profile (SWP, single well profile) gathers. After that, geometry was reconstructed closer to the structure targets near wells to get the better image resolution of subsurface geological body, and the seismic source and geophone under complex overburden to avoid the effect by unknown velocity information between wells and surface. Especially, when the steep structure such as faults present in the subsurface, the virtual source method can produce better image results. The authors modeled acoustic and elastic data, set the faults as steep structures, and tested the ability of virtual source method to detect the steep structure in the subsurface, which obtained the satisfactory imaging results of acoustic and elastic medium. This method still gets the good imaging results when sparse geometry was used to survey.