Modified Reverse-Time Migration Applied to Offset VSP Data Acquired in Area with Complex Geological Conditions

Neklyudov, Dmitry; Borodin, I.

doi:10.3997/2214-4609.201401761

Cited by 3 publications

(2 citation statements)

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“…He ͑2006͒ and He et al ͑2007͒ use one forward propagation and one backward propagation of the recorded wavefield from the receiver side to image the local reflectivity; in this approach, two backward propagations from the receiver side are used. A similar strategy is proposed by Neklyudov andBorodin ͑2007͒ andHe et al ͑2008͒.…”

Section: Theorymentioning

confidence: 81%

Local vertical seismic profiling (VSP) elastic reverse-time migration and migration resolution: Salt-flank imaging with transmitted P-to-S waves

2010

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To avoid the defocusing effects of propagating waves through salt and overburden with an inaccurate overburden velocity model, we introduce a vertical seismic profiling ͑VSP͒ local elastic reverse-time-migration ͑RTM͒ method for salt-flank imaging by transmitted P-to-S waves. This method back-projects the transmitted PS waves using a local velocity model around the well until they are in phase with the back-projected PP waves at the salt boundaries. The merits of this method are that it does not require the complex overburden and salt-body velocities and it automatically accounts for source-side statics. In addition, the method accounts for kinematic and dynamic effects, including anisotropy, absorption, and all other unknown rock effects outside of this local subsalt velocity model. Numerical tests on an elastic salt model and offset 2D VSP data in the Gulf of Mexico, using a finite-difference time-domain staggered-grid RTM scheme, partly demonstrate the effectiveness of this method over interferometry PS-PP transmission migration and local acoustic RTM. Our method separates elastic wavefields to vector P-and S-wave velocity components at the trial image point and achieves better resolution than local acoustic RTM and interferometric transmission migration. The analytical formulas of migration resolution for local acoustic and elastic RTM show that the migration illumination is limited by data frequency and receiver aperture, and the spatial resolution is lower than standard poststack and prestack migration. This new method can image salt flanks as well as subsalt reflectors.

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Section: Theorymentioning

confidence: 81%

Local vertical seismic profiling (VSP) elastic reverse-time migration and migration resolution: Salt-flank imaging with transmitted P-to-S waves

2010

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“…When reflections from the flank are not recorded in a well with a given geometry of observations, the problem of flank imaging may be solved by using transmitted converted PS‐waves (Li et al 2002; Luo et al 2006; Neklyudov and Borodin 2007). The velocity of seismic waves in salt is typically much higher than in the surrounding rocks.…”

Section: Methodsmentioning

confidence: 99%

Imaging of offset VSP data acquired in complex areas with modified reverse‐time migration

Neklyudov¹,

Borodin²

2009

Geophysical Prospecting

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A B S T R A C TA modified reverse-time migration algorithm for offset vertical seismic profiling data is proposed. This algorithm performs depth imaging of target areas in the borehole vicinity without taking into account the overburden. Originally recorded seismograms are used; reliable results can be obtained using only the velocity profile obtained along the well. The downgoing wavefield emitted from a surface source is approximated in the target area using the transmitted P-wave, recorded by the receivers deployed in the well. This is achieved through a reverse-time extrapolation of the direct transmitted P-wave into the target area after its separation in offset vertical seismic profiling seismograms generated using a finite-difference scheme for the solution of the scalar wave equation.The proposed approach produces 'kinematically' reliable images from reflected PPand PS-waves and, furthermore, can be applied as a salt proximity tool for salt body flank imaging based on the transmitted PS-waves. Our experiments on synthetic data demonstrate that the modified reverse-time migration provides reliable depth images based on offset vertical seismic profiling data even if only the velocity profile obtained along the borehole is used.

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Local migration with extrapolated VSP Green’s functions

Xiao

Schuster

2009

GEOPHYSICS

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We have developed a novel vertical seismic profile ͑VSP͒ imaging method that requires only a local velocity model around the well. This method is denoted as a "local migration," where the model-based forward-propagation and backward-propagation operators are computed using a local velocity model between the well and the target body. The velocity model for the complex overburden and salt body is not needed, and the source-side statics are automatically accounted for. In addition, kinematic and dynamic effects, including anisotropy, absorption, and other unknown/undefined rock effects outside of this local velocity model, are mostly accounted for. Numerical tests on an acoustic 2D Sigsbee VSP data set, an elastic salt model, and offset 2D VSP data in the Gulf of Mexico partly validate the effectiveness of this method by accurately imaging the sediments next to the vertical well.

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Modified Reverse-Time Migration Applied to Offset VSP Data Acquired in Area with Complex Geological Conditions

Cited by 3 publications

References 0 publications

Local vertical seismic profiling (VSP) elastic reverse-time migration and migration resolution: Salt-flank imaging with transmitted P-to-S waves

Local vertical seismic profiling (VSP) elastic reverse-time migration and migration resolution: Salt-flank imaging with transmitted P-to-S waves

Imaging of offset VSP data acquired in complex areas with modified reverse‐time migration

Local migration with extrapolated VSP Green’s functions

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