Abstract:Usually Walkaway VSP and 3D VSP upgoing wave imaging is used to study structure and reservoir characteristics around wells,and free-surface multiple waves are removed as noise.Compared with upgoing waves,the free-surface multiple waves are characterized by easy identification,wide illumination,small reflection angle,and long propagation path.So we propose a prestack depth migration of Walkaway VSP free-surface multiple waves.The main steps of our idea are:①Z-component common-shot-point gathers are arranged into common-receiver-point gathers; ②According to the reciprocity principle of shot-point and receiver-point,the source wavelet is extended from the receiver point to the free-surface with the domain displaying one-way wave operator; ③The free-surface are extended respectively from the common-receiver point wavefield and the source wavefield; ④The imaging values are extracted with relevant imaging conditions and the prestack depth migration imaging is realized.Model and real tests show:①Prestack depth migration imaging of one-way waves along free-surface multiple wave path ma-tches well with seismic section waveforms,the proposed approach is simple,and easy to be programmed; ②Compared with primary reflection wave,the free surface multiple waves imaging have a wider range of vertical and horizontal illumination,and can achieve imaging above geophones,but their frequency is low.
李鹏,刘伊克,常旭,等.多次波问题的研究进展[J].地球物理学进展,2006,21(3):888-897.LI Peng,LIU Yike,CHANG Xu,et al.Progress on the multiple problems[J].Progress in Geophysics,2006,21(3):888-897.
[2]
吴世萍,黄录忠,胡天跃.Walkaway VSP多次波成像技术研究[J].石油物探,2011,50(2):115-123.WU Shiping,HUANG Luzhong,HU Tianyue.Multiple reflection imaging by using Walkaway VSP data[J].Geophysical Prospecting for Petroleum,2011,50(2):115-123.
[3]
Sheng J M.Migrating multiples and primaries in CDP data by crosscorrelogram migration[C].SEG Technical Program Expanded Abstracts,2001,20:1297-1300.
[4]
Yu J,Schuster G.Cross correlogram migration of IVSPWD data[C].SEG Technical Program Expanded Abstracts,2001,20:456-459.
[5]
Shan G.Source-receiver migration of multiple reflec-tions[C].SEG Technical Program Expanded Abstracts,2003,22:1008-1011.
[6]
Berkhout A J,Verschuur D J.Transformation of multiples into primary reflections[C].SEG Technical Program Expanded Abstracts,2003,22:1925-1928.
[7]
Berkhout A J,Verschuur D J.Imaging of multiple reflections[J].Geophysics,2006,71(4):S209-S220.
[8]
单国健.地表多次波应用研究[J].石油物探,2007,46(6):604-610.SHAN Guojian.Surface-related multiple migration[J].Geophysical Prospecting for Petroleum,2007,46(6):604-610.
[9]
郭书娟,李振春,仝兆岐.表层多次波成像方法技术研究[J].地球物理学进展,2012,27(6):2570-2576.GUO Shujuan,LI Zhenchun,TONG Zhaoqi.Method and technique for imaging of surface-related multiples[J].Progress in Gephysics,2012,27(6):2570-2576.
[10]
Guittton A.Shot-profile migration of multiple reflections[C].SEG Technical Program Expanded Abstracts,2002,21:1296-1299.
[11]
Muijs R,Robertsson A J O,Holliger K.Prestack depth migration of primary and surface-related multi-ple reflections,Part I:Imaging[J].Geophysics,2005,72(2):S59-S69.
[12]
Liu Y K,Chang X,Jin D G,et al.Reverse time migration of multiples for subsalt imaging[J].Geophysics,2011,76(5):WB209-WB216.
[13]
Wang Y B,Chang X,Hu H.Simultaneous reverse time migration of primaries and free-surface related multiples without multiple prediction[J].Geophysics,2014,79(1):1-9.
[14]
刘守伟,王华忠,陈生昌.VSP上下行反射波联合成像方法研究[J].地球物理学报,2012,55(9):3126-3133.LIU Shouwei,WANG Huazhong,CHEN Shengchang.Joint imaging method of VSP upgoing and downgoing reflection wave[J].Chinese Journal of Geophysics,2012,55(9):3126-3133.
[15]
王华忠,徐蔚亚,王建民,等.VSP数据波动方程叠前深度偏移成像及立体地震成像[J].石油地球物理勘探,2001,36(5):517-525.WANG Huazhong,XU Weiya,WANG Jianmin,et al.Prestack depth migration of VSP data and stereosco-pic seismic imaging[J].Oil Geophysical Prospecting,2001,36(5):517-525.
[16]
方伍宝,陈林.三维VSP资料波动方程叠前深度偏移研究[J].石油物探,2006,45(5):527-531.FANG Wubao,CHEN Lin.Wave equation of prestack depth migration of 3-D VSP data[J].Geophysical Prospecting for Petroleum,2006,45(5):527-531.
[17]
Ferguson R J,Margrave G F.Planned seismic imaging using explicit one-way operators[J].Geophysics,2005,70(5):S101-S109.