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Regional time-depth conversion of the Natih E horizon in Northern Oman using seismic stacking velocitiesNormal access

Authors: P.C.H. Veeken, J. Filbrandt and M. Al Rawahy
Journal name: First Break
Issue: Vol 23, No 8, August 2005 pp. 35 - 45
DOI: 10.3997/1365-2397.2005015
Language: English
Info: Article, PDF ( 799.9Kb )
Price: € 30

A method is presented for integrating stacking velocity data in the time-depth conversion of regional time horizons in North Oman (Fig. 1). The Natih E horizon has been chosen as the target for the depth conversion as it forms a well-defined seismic reflection in Northern Oman (Figs. 2 and 3). The Cretaceous Natih Formation is composed of a series of limestone beds, ranging in age from latest Albian to Early Turonian. Timeequivalent source rocks occur (Van Buchem et al., 1996) in addition to organic-rich sediments in older formations, making the hydrocarbon charge for the mapped traps less of a problem. Conventional well-based time-depth (TD) conversion methods have their limitations, especially when dealing with vast areas, irregular distribution of control points, and a complex subsidence history (local inversion tectonics; e.g. Veeken, and Van Moerkerken, in preparation). Most methods are only appropriate when enough well penetration is available to calibrate the data set. If too large an interpolation or extrapolation distance is given, then these methods become notoriously unreliable. In such cases, seismic stacking velocities may provide the only means to evaluate the subsurface structuration (Veeken, 2005). The velocity cube represents an excellent asset for detailed prospect evaluation (Schulz, 1999). Many essential reservoir attributes are based on seismic velocities (e.g. impedance contrasts) and therefore it is worthwhile expending some effort exploring all of its benefits.

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