Depth registration of P-wave and C-wave seismic data for shallow marine sediment characterization, Gulf of Mexico

Abstract

Multicomponent seismic data, combining P-wave and converted P-to-SV wave (C-wave) wavefields, provide independent measurements of rock and fluid properties. Unlike P waves, C waves are minimally affected by changes in pore fluids, and in cases of azimuthal anisotropy, will be split into two modes (fast and slow) with differing polarization. The 4C, 3D ocean-bottom cable (OBC) multicomponent seismic data discussed here were acquired in shallow water (<300 ft) offshore Louisiana over approximately 455 miles 2 (Figure 1). Because these data are still being marketed to interested oil and gas operators, only data above targeted oil and gas reservoirs (<5000 ft) were used. The P-wave migrated data extend to only 1 s and the C-wave migrated data volume to only 2 s. The initial objectives of the survey were to improve Pwave reflection quality by combining hydrophone and vertical-geophone data and to improve structural interpretation in the presence of "gas clouds" with C-wave data. Our additional research objectives were to evaluate seismic attributes, such as V P /V S velocity ratios and Poisson's ratio derived from

Support of Gulf of Mexico Hydrate Research Consortium: Activities to Support Establishment of a Sea Floor Monitoring Station Project

“…Dilutions of 48μM ammonium, 8μM phosphate, and 4μM nitrate+nitrite were run as the standard curve. Nutrient concentrations were only measured on the May 2005 cruise samples (cores [1][2][3][4][5][6][7][8][9][10].…”

“…Typical sampling rate 1 Hz Peak sampling rate 1 Hz Typical data transfer rate (per sensor) 768 bps N,8,1) Peak data transfer rate (per sensor)…”

“…The software was developed in IDL 8 . The reasons for this choice were that: • IDL provides a powerful environment that allows rapid software development, with an extensive mathematical library, as well as built-in visualization and GUI tools.…”

SV-P and S-S imaging at a CO2 storage site using vertical seismic profiling data

“…Some S-waves are converted from P-waves at interfaces that separate rock layers with different bulk densities and/or seismic wave velocities. Shear waves are highly sensitive to geological heterogeneities (MacLeod et al, 1999;DeAngelo et al, 2003;Stewart et al, 2003), and application of S-wave reflection seismology extends capabilities for subsurface exploration. To analyze S-waves, one needs to use horizontal geophones and common practice is to deploy three mutually orthogonal geophones that collect three-component (3C) seismic data.…”

Estimating VP/VS ratios using smooth dynamic image warping

“…In fact, it is possible for a reflector in one image to not be apparent in the other image. For these reasons, image registration is often done by manually selecting corresponding events in each image (DeAngelo et al, 2003). Nevertheless, many techniques have been developed to automate the registration process and to estimate V P ∕V S ratios (Gaiser, 1996;Fomel and Backus, 2003;Nickel and Sonneland, 2004;Fomel et al, 2005;Yuan et al, 2008).…”