山前带地震数据成像处理流程探讨  

Discussion on the imaging processing workflow for foothill seismic data

作　　者：王华忠[1] 张兵[1,2] 刘少勇[1] 徐兆涛[2] 蔡杰雄[1,2] 王立歆[2] 方伍宝[2] 杨勤勇[2] 

机构地区：[1]同济大学海洋与地球科学学院波现象与反演成像研究组,上海200092 [2]中国石油化工股份有限公司石油物探技术研究院,江苏南京211103

出　　处：《石油物探》2012年第6期574-583,597,共11页Geophysical Prospecting For Petroleum

基　　金：国家科技重大专项(2011ZX05005-005-008HZ)项目资助

摘　　要：山前带地震勘探中地震数据成像处理的特殊性来自于复杂的地表条件,它导致了地震数据的低信噪比和剧变的道间时差。地表高程剧烈变化以及地表横向变速使得常规的基于CMP道集叠加的均方根速度分析过程不再有效。到目前为止,还没有一个得到较广泛认可的、有效的成像处理流程来解决实际的山前带地震数据成像问题。在分析山前带地震波传播和常规处理方法局限性的基础上,提出了一个新的成像处理流程,关键环节包括:①选择尽可能接近地表的、比较光滑的基准面作为消除高频道间时差的标准,此基准面也是后续叠前深度成像和速度建模的起始深度面;②以Kirchhoff积分法叠前深度偏移算子为引擎的Monta Carlo方法初始背景速度反演;③以Beam波积分法叠前深度偏移算子为引擎,进行基于成像点道集的剩余速度分析和基于角度道集的层析速度反演。另外,去噪或提高信噪比主要依赖于基于Fresnel半波带的同相叠加方法;静校正主要靠浅层层析速度建模和中深层层析速度建模的联合来统一解决,不再强调表层静校正处理。初步的数值试验验证了上述流程的有效性。The specialty of seismic imaging in foothill area originates from the complex surface conditions,which leads to low S/N and serious moveout between gathers.Because of the rugged topography and near-surface lateral velocity variation,the conventional root-mean-square velocity analysis based on CMP gathers stacking is no longer effective.Up to now,there does not exist an effective imaging processing procedure widely accepted for foothill seismic data.After analyzing the seismic wave propagation and the limitation of conventional processing methods,we proposed a new imaging workflow.The workflow includes three key steps:①choosing a smoothed datum as close to the topography to remove the high wavenumber moveout.The prestack depth migration and velocity model building are also based on the datum;②Kirchhoff PSDM based Monta Carlo velocity inversion is used to estimate the background and smoothed initial velocity.③beam ray PSDM based velocity tomography in angle domain is used to estimate the more fine and accurate migration velocity.In addition,the in-phase stacking the reflections from half Fresnel band is used to do the noise attenuation,which is very important for the effective migration velocity estimation and velocity model building.The near-surface velocity model building replaces the so-called static correction.The basic numerical tests demonstrate the effectiveness of this procedure.

关 键 词：山前带地震勘探 成像处理流程 速度估计 速度建模 叠前深度偏移 

分 类 号：P631.4[天文地球—地质矿产勘探]