Enhancement of temporal and spatial resolution of 2-D reflection data: application to Texaco data over Venice Dome in Plaquemines Parish, Louisiana

Combined with a conventional processing scheme, applications of stretched amplitude adjustment (SAGC), pre-stack deconvolution, and post-stack migration improve the temporal and spatial resolution of Texaco Line 6, facilitating interpretation of the salt structure geometry beneath the line. Applied through DISCO (Cogniseis) processing software along with modules developed at Virginia Tech, SAGC and prediction-error deconvolution perform whitening to enhance temporal resolution while post-stack signal enhancement and a migration edge effect attenuation (MEE) scheme improve the accuracy of Kirchoff, finite-difference, omega-x, and f-k migrations to enhance spatial resolution. Synthetic seismograms generated from checkshot velocity data tie the seismic horizons to subsurface geology. Complex trace analyses, carried out using FOCUS 2-D (Cogniseis) software, elaborate on reflector continuity and hydrocarbon accumulation. Overall, amplitude spectra of pre-stack data are enhanced by a maximum of 14 decibels between 10 and 58 Hz after SAGC and 4 decibels between 17 and 58 Hz after deconvolution. Signal enhancement improves reflector amplitude to optimize hyperbola collapse through migration. MEE expands the migration cone spatially by 3,503.7 m and temporally by approximately 42 percent, and the Kirchoff algorithm provides the most accurate migration.

Pre-stack migration by Texaco reveals subhorizontal strata having a minimum period of 33.3 ms near the northeast flank of Venice Dome salt; the salt has an upward extent of 2,250 ft and is covered by smooth caprock. Resolution gains after reprocessing show strata having a minimum period of 25.0 ms; the salt is imaged deeper at 2,950 ft with a more southwesterly flank and is covered by faulted caprock. Seismic horizons correlate with Pleistocene to Miocene sand and shale layers associated with hydrocarbon production; increased resolution suggests the presence of geologic discontinuities which could interfere with producibility. Increasing seismic resolution by reprocessing existing reflection data exhibits that salt structure geometry and potential hydrocarbon traps can be better evaluated so as to help identify future prospects.