火成岩区二维地震正演及照明分析技术应用

Application of 2-D seismic forward modeling and illumination analysis in igneous rock area.

由于海南福山凹陷表层及浅层火成岩异常发育,导致该地区多次反射波、折射波等干扰波现象非常突出,地震有效信号成像困难,地震资料分辨率、信噪比低,地震资料品质差。为了研究火成岩与地震资料品质之间的关系,针对地震目的层的反射特点,利用地震解释成果及测井资料建立地质模型,通过二维模型正演与照明分析技术研究多次波、折射波等干扰波的形成机理。通过研究分析认为:①表层风化层等低速层对地震资料高频吸收强烈,应在地表风化层下激发;②浅层火成岩是影响地震资料品质的关键因素,在浅层火成岩之下激发能获得较高品质的地震资料;③适当增加激发能量,并根据不同的地表特点调整覆盖次数来提高反射能量;④地震模型正演与照明分析技术有助于区分多次波和有效反射波,可以用来指导地震资料采集及数据处理工作。

Igneous rock is well developed in shallow layer and near-surface layer in Fushan sag of Hainan,which results in multiples and refraction waves and hampers imaging of seismic data.In order to find out the relationship between the igneous rock and seismic data quality,according to the features of target layers,we established a geological model by using seismic data interpretation results and well data,and studied the variability of the multiples and refraction waves by using forward modeling and illumination analysis.It is concluded that near-surface weathering layer absorbs much of the high frequencies in seismic waves,and shot should be conducted under the near-surface weathering layer.Shallow igneous rock is the key factor that affects the quality of seismic data.In order to get high quality seismic data,shot should be under the shallow igneous rock.Increasing the energy of shot in certain range is favorable and different folds should be adopted in different areas.Seismic forward modeling and illumination analysis are helpful for distinguishing multiples from effective reflection waves,and can be used to guide the seismic acquisition and seismic data processing.