正演模型在复杂地区观测系统设计中的应用

Application of Forward Simulation Model in Complex Area Field Setup Design

在复杂地区进行煤田地震勘探,受低速带变化剧烈、倾角大及构造复杂等因素影响,依靠经验设计的观测系统往往存在较大缺陷。利用Klseis软件,根据预先了解的目的层埋藏深度及构造发育情况,建立初始正演模型,设置相关参数,并通过观察不同参数下的射线分布情况及模拟时间剖面,直观地判断模型最佳设置,为观测系统设计提供依据。通过对大倾角目的层及新生界厚度变化剧烈的二维模型进行射线追踪模拟,发现大倾角地层的有效信号,若道距较大,其远端易受直达波干扰;新生界厚度变化剧烈的地震有效波,则存在远炮点严重干扰现象。

Coalfield seismic prospecting in complex area, because of impacts from abrupt changes of weathering zone, large dip angle and complex structure, field setup designed rely on experiences sometimes has major defects. By the use of Klseis software, according to beforehand known target layer buried depth and structure development, established initial forward simulation model, set related parameters, observed ray distribution under different parameters and simulated time sections, visually judging optimal setting of model, provide basis for field setup design. Through large dip angle target layer and abrupt changing Cenozoic thickness 2D model ray tracing simulation, found effective signals of large dip angle strata. If group interval is too large, its distal end will easy to be interfered by direct wave. Effective wave of abrupt changing Cenozoic thickness, far shotpoint serious interference will be existed.