塔里木盆地哈拉哈塘地区二叠系火成岩体对下伏地层地震成像影响

塔里木盆地哈拉哈塘地区二叠系发育大规模火山活动，为准确了解厚层火山岩对下伏地层地震成像的影响，在实际钻测井资料及三维地震资料的基础上，建立寒武系—白垩系简化地质模型，并采用有限差分法求解弹性波波动方程，开展波动方程正演模拟，真实还原地震成像过程，明确二叠系火成岩体对下伏地层地震成像的影响，以期对哈拉哈塘地区古生界油气勘探开发起到一定的借鉴作用。结果表明：高速、高密度的二叠系英安岩对下伏地层地震成像有屏蔽作用，下伏地层反射波振幅强度相对于覆盖区外围明显减弱；由于岩性的横向突变，致使其下伏地层的地震成像形态发生明显变形及构造异常，而并非断裂带或火山通道的地震响应；杂乱反射带及火成岩下伏区域奥陶系大型缝洞集合体波场复杂，成像速度较难准确求取，存在偏移假象，“串珠状”地震反射难以收敛。

The influence of Permian igneous rock on the seismic imaging of underlying strata in Hanilcatam area,Tarim Basin

In order to get an accurate view of the influence of thick igneous rock on the seismic imaging of the underlying strata,based on the actual drilling and logging data and the 3D seismic data,the Cambrian-Cretaceous simplified geologic model,and the finite difference method are used to solve the elastic wave equation.The forward equation simulation of the wave equation is carried out,the true restoration seismic imaging process is carried out,and the influence of the Permian igneous rock body on the seismic imaging of the underlying strata is discussed.Paleozoic oil and gas exploration and development play a certain reference.The results show that the high-speed and high-density Permian dacite have shielding effect on the seismic imaging of the underlying strata,and the amplitude of the reflected wave of the underlying strata is obviously weakened relative to the periphery of the covering area.Due to the lateral mutation of the lithology,the seismic imaging of the layers has obvious deformation and tectonic anomalies,rather than the seismic response of the fault zones or volcanic channels.The wavefield of fracture-cavern body in the disorder reflection region and underlying region of volcanics is very complex and the imaging velocity is difficult to pick accurately,which leads to distorted migration results and not convergent bead-like reflection.