Click to view article in PDF format.
GCGeological Input Valuable in Seismic Velocity
Analysis
*
Supratik Sarkar1
Search and Discovery Article #41118 (2013)
Posted March 18, 2013
*Adapted from the Geophysical Corner column, prepared by the author, in AAPG Explorer, January, 2013, and entitled "Time to Pick? No Need to Fear 'Seismophobia' ". Editor of Geophysical Corner is Satinder Chopra ([email protected]). Managing Editor of AAPG Explorer is Vern Stefanic.
11Shell, Deepwater/Frontier New Ventures Business Development Group, Houston, TX ([email protected])
While seismic processing shops usually are the "professionals" when it comes to velocity
analysis
, the interpreter may have greater insight into the cause of the poor
data
quality. In such cases, repacking the velocities on a tight grid with a better knowledge of the geology can provide significant improvement.
|
The following example (Figure 1) is from a tight turbidite formation in Mexico's Chicontepec Basin, where the The original Maps of the volcanics were made to highlight the problem areas. The original migration velocities were then removed (Figure 1b) using simple reverse normal moveout, followed by a The key step was to take care beneath the volcanics to pick the slower Chicontepec reflectors rather than the strong, slightly faster interbed multiples (Figure 1a), resulting in the flattened gathers like the one shown in
Figure 1c. After the residual Descriptions of several volcanic episodes in east-central Mexico, from the Late Cretaceous to Miocene, have been published. The burial history chart from the adjacent Veracruz Basin - where petroleum generation occurred from Upper Jurassic source rocks similar to those in the Chicontepec play - shows that oil generation and migration started around 20 Ma and continued through the Miocene. Since most of the oil migrated after the major volcanic activities, improving the imaging below the volcanics also provided us ideas on how the volcanic bodies enhanced fracture porosities in reservoirs in some areas - especially through enhanced seismic attribute images. This I wish to thank my adviser, AAPG member Kurt J. Marfurt from the University of Oklahoma, for his constant persistence and encouragement (to a geologist) to complete the work, part of which is reflected in this article. I also would like to thank Pemex, as well as Sergio Chavez Perez from IMP, who provided the |