Full text loading...
-
Seismic Velocity Uncertainty Analysis In An Underexplored Basin
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, IPTC 2013: International Petroleum Technology Conference, Mar 2013, cp-350-00362
Abstract
In areas characterized by complex geology, Depth Velocity Analysis is the mandatory instrument to estimate the sharp velocity variations that can be expected; seismic data and processing tools are necessary but not sufficient ingredients for successful depth imaging results, so sound a priori information must be retrieved from well information and from the geological knowledge of the area of study, as well as a close integration between the geophysical and geological contexts. A proper estimation of seismic velocities is not only fundamental to obtain good imaging quality and correct depth positioning, but it can also be a key input for detecting the presence of overpressures: usually, overpressured areas are associated with seismic velocity inversions. Moreover, in areas where anisotropy is unknown because of lack of well information, seismic velocities are affected by uncertainty: this must be taken into account in order to quantify the consequent uncertainty both in depth positioning of the target and in pore pressure prediction. In this paper a case history from Offshore Ghana is presented, dealing with the above mentioned issues: the intimate correlation that exists between anisotropy and velocity analysis is investigated, and the impacts of the uncertainty that affects them is considered.