Imaging above an extended-reach horizontal well using converted shear waves and a rig source

Haldorsen, J.; Leaney, W. Scott; Coates, R.; Petersen, S. A.; Rutledal, H.; Festervoll, Kjetil

doi:10.1190/geo2012-0154.1

Cited by 5 publications

(1 citation statement)

References 17 publications

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“…Otherwise, more traditional salt proximity surveys (Lou et al ., 2012), refraction imaging (e.g. Haldorsen et al ., 2013c; Haldorsen and Jahren, 2020), either using rays penetrating through the salt.…”

Section: Applicationmentioning

confidence: 99%

Imaging complex three‐dimensional structures, applying three‐component vector migration to synthetic vertical seismic profiling data

Haldorsen

Jahren

2021

Geophysical Prospecting

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By applying a ray‐based three‐dimensional vector migration process to fully elastic three‐component synthetic Vertical Seismic Profiling data, we are able to demonstrate that the process gives an accurate compressional reflection image of the complex formation without much visible artefacts from spatial aliasing, or from ‘migration smiles’ caused by the limited aperture of the receiver array. We demonstrate that the process reconstructs images of both steeply dipping salt flanks, and the sediments that tend to be dragged along by the moving salt and truncated against the sides of the salt body. The process uses raw unseparated data as input, and the wavefield separation of compressional and shear waves are done by projection operators inside the kernel of the migration process. The compressional reflection image appear to have no visible artefacts from the abundance of converted shear.

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Section: Applicationmentioning

confidence: 99%

Imaging complex three‐dimensional structures, applying three‐component vector migration to synthetic vertical seismic profiling data

Haldorsen

Jahren

2021

Geophysical Prospecting

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Locating microseismic sources using migration-based deconvolution

Haldorsen¹,

Brooks²,

Milenkovic³

2013

GEOPHYSICS

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We have developed a method for finding microseismic hypocenters from data recorded by arrays of triaxial motion sensors. The method reconstructs the elastic time-series signatures for possible microseismic sources at any point in 3D space, using full-waveform migration of the recorded vector wavefield. The imaging condition for the migration is based on a semblance-weighted deconvolution between two or more reconstructed source signatures, requiring similarity and simultaneity of the reconstructed signatures. This imaging condition eliminates the need for an absolute timing of the data, gives optimum resolution for the location of the microseismic sources—better than correlation-based approaches—and ensures numerical stability by adapting to the signal and noise conditions of the data. Because the method eliminates time-consuming phase picking and traditional event association, it should be well suited for fully or semiautomated data processing. The method was tested by an application to field data acquired with arrays of three-component receivers in two deep wells. Nevertheless, the formulation is equally applicable to data acquired by a distribution of single three-component receivers, or local arrays of these, deployed at the surface or in one or several shallow wells.

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True amplitude recovery in reverse time extrapolation of plane and spherical waves

McMechan

2018

GEOPHYSICS

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A challenging outstanding problem in reverse time extrapolation is recovering accurate amplitudes at reflectors from the receiver wavefield. Various migrations have been developed to produce accurate image locations rather than correct amplitude information because of inadequate compensation of attenuation, dispersion, and transmission losses. We have evaluated the requirements, and determined the theoretical feasibility, of true amplitude recovery of 2D acoustic and elastic seismic data by using the analytic Zoeppritz equations for plane-wave reflection and transmission coefficients. Then, we used synthetic acoustic and elastic wavefield data generated by elastodynamic finite differences to verify the recovery, in the reverse time propagation, of spherical waves and illustrated the salient differences between the incident wavefields reconstructed from reflection data only and from the combination of reflection and transmission data. These examples quantitatively verify that recovering an incident plane or a spherical wave requires the reverse time propagation of all reflections and transmissions in a model with the correct velocity and density. Accurate reconstruction of an incident wave is not possible by backward propagation of only reflections. As an application, we removed downgoing internal multiple reflections generated by upgoing waves incident at reflectors shallower than a horizontal well, in which geophones are deployed. The subtraction of the downgoing reflection involves wavefield reconstruction at depths shallower than the horizontal well and separation of upgoing and downgoing wavefields. This approach assumes that the correct acoustic (or elastic) velocity and density models are available in, and shallower than, the layer where the horizontal well is located. Incident-wave reconstruction works equally well for smooth models, as for models with sharp boundaries. Uncertainties in the model used for reconstruction, and incompleteness of the data aperture are propagated into the equivalent uncertainties, and incompleteness of the reconstruction.

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Imaging above an extended-reach horizontal well using converted shear waves and a rig source

Cited by 5 publications

References 17 publications

Imaging complex three‐dimensional structures, applying three‐component vector migration to synthetic vertical seismic profiling data

Imaging complex three‐dimensional structures, applying three‐component vector migration to synthetic vertical seismic profiling data

Locating microseismic sources using migration-based deconvolution

True amplitude recovery in reverse time extrapolation of plane and spherical waves

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