High-fidelity walkaround VSP anisotropy analysis

Owusu, J.C.; Mubarak, Saeed; Liu, Qinglin

doi:10.1190/1.3192842

Cited by 6 publications

(2 citation statements)

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“…Analyses of such surveys have been limited to direct Pwave attributes and S-wave birefringence (e.g., Owusu et al, 2009). Analyses of such surveys have been limited to direct Pwave attributes and S-wave birefringence (e.g., Owusu et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Vertical Seismic Profile Complete Session

2016

SEG Technical Program Expanded Abstracts 2016

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Section: Introductionmentioning

confidence: 99%

Vertical Seismic Profile Complete Session

2016

SEG Technical Program Expanded Abstracts 2016

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“…This happens mainly close to the reservoir, where the velocity difference between cap rock and porous formations changes vertically and the fluid saturation changes laterally and also in the near‐surface, where the changes in P‐ and S‐wave velocities and structural heterogeneity can be even larger. As a detailed Earth model is rarely available, a statistical method is adopted to allow for these effects; the geophone rotation is estimated using different source positions at the Earth's surface and these different results are averaged (Owusu et al 2009; Al‐Dulaijan et al 2011). This approach is quite robust but any averaging process implies a smoothing of the underlying Earth model.…”

Section: Introductionmentioning

confidence: 99%

Borehole receiver orientation using a 3D velocity model

Menanno

Vesnaver

Jervis

2012

Geophysical Prospecting

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A B S T R A C TThe orientation of three-component borehole geophones used for recording during a microseismic monitoring experiment is estimated. The standard technology for deploying multi-component geophones in a deep borehole is wireline-based, in which the azimuthal rotation of the geophone string cannot be controlled. Each receiver can have a different rotation angle that is compensated by the particle motion analysis of the direct P-wave arrivals, picked from a walk-around VSP carried out in the proximity of the well. Knowing the orientation of borehole receivers is critical, as inaccuracies lead to systematic errors in determining the hypocentral coordinates of microseismic events. Additional errors arise from over-simplifications of P-and S-wave velocity Earth models.In this paper, we propose a tomographic approach for improving the orientation estimates of borehole receivers based on hodogram analysis. The initial velocity model built from well logs and upholes is refined by 3D tomographic inversion of walkaround VSP data and some string shots fired in a nearby borehole. Taking into account ray bending, the estimated errors due to local velocity anomalies can be reduced. This makes our estimates of fracture orientation and microseismic hypocentres more reliable when borehole receivers are used in passive seismic surveys.

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