Analyzing three‐component 3D vertical seismic profiling data

Abstract

A three-component 3D vertical seismic profile (VSP) was acquired over the Blackfoot oil field in Alberta, Canada. The VSP survey was recorded simultaneously with a surface seismic program. The objectives of the VSP were to develop recording logistics, data handling, and processing procedures and to determine if the 3D VSP volumes could image the glauconitic sand reservoir of the Blackfoot field.Dynamite shots from the surface seismic survey, which fell within a 2200-m offset from the recording well, were used in the VSP analysis. The shots were recorded by a string of three-component borehole receivers that was moved seven times, resulting in a receiver depth range of 400 to 910 m. The borehole data were processed using basic VSP processing techniques that included hodogram analysis, wavefield separation using median filters, and VSP deconvolution. The final P-P and P-S image volumes were obtained by VSP common-depth point and VSP common-conversion point stacking the upgoing wavefields followed by f -x y deconvolution. The P-P and P-S images from the VSP correlate well with those from the surface seismic survey. Time slices from the VSP also indicate the trend of the sand channel of the Blackfoot field.

Parsimonious migration of 3-C 3D VSP data

“…The surface fitting uses Delaunay ͑1934͒ triangulation ͑e.g., Kalbacher et al, 2005͒ with constrained smoothing. The region imaged by the P-S conversion is closer to the borehole than that of the P-P image ͑Fig-ure 8e͒, as expected from Snell's law ͑e.g., Gulati et al, 2004͒. .…”

“…Keho and Wu ͑1987͒ do elastic Kirchhoff migration for VSP data, and Keho et al ͑1983͒ consider effects of radiation pattern and attenuation on 3-C VSP data. Scalar migration of 3-C data may be performed by first separating P-and S-waves, then extrapolating them separately ͑Nolte et al., 1999;Gulati et al, 2004͒. Various algorithms have been proposed to separate P-and S-waves ͑Dankbaar, 1987; Dellinger and Etgen, 1990;Esmersoy, 1990;Amundsen and Reitan, 1995;Wang and Nemeth, 1997;Sun and McMechan, 2001;Sun et al, 2004͒.…”

Shear Wave Splitting Analysis to Estimate Fracture Orientation and Frequency Dependent Anisotropy

“…Hodogram analysis is based on the amplitudes in the short time windows given by the first breaks of 3C data. Its basic principle is to use the amplitude cross-plot of first breaks in an orthogonal coordinate system to find the wavefield polarization angle between two component data (Gulati et al 2004). After polarization analysis of raw X-and Y-components, there will be two new components known as H (horizontal) and T (transverse) components containing P-waves and SV-waves travelling in the vertical plane and S h wave travel perpendicular to this plane, respectively.…”

Fault mapping using a generalized image point transform of three dimensional reverse VSP data

“…Vertical seismic profiling (VSP), as a subsurface imaging tool, has been widely applied not only to the natural resources exploration, such as gas, fuel, and oil fields (Yilmaz, 2001;Gulati et al, 2004), but also to geotechnical problems like the monitoring of CO 2 sequestration (Daley et al, 2008), the assessment of disposal site survey for high-level radioactive material disposal (Cosma and Heikkinen, 1996), and the identification of fracture zones in tunneling (Ashida et al, 1998).…”