Time-to-Depth Conversion

Accurate time-to-depth conversion is essential for generating, assessing prospects and well planning. Our methodologies handle depth conversion making use of seismic and well velocities, which has significant advantages over typical single-function conversion. Seismic velocities were improved in terms of higher resolution (left figure) and structural heterogeneity. The result of geostatistical Kriging shows directional lateral heterogeneity.

  
 Client’s depth map (left) vs. SeisLink depth map (right)
 Drilling result confirmed SeisLink’s map

Indicating rock property changes in NNW direction. As a result of check-shot calibration, the prospect size was 40% smaller. Only one check-shot made the difference for this work in a 200-block offshore area. Geostatistical methodologies for velocity modeling and calibration offer advantages since they can easily discriminate blunders velocity picks. The drilling result confirmed that our evaluation was accurate.

Well Locations in a Development Field

Even geologically less-complicated area can have complicated-velocity fields and pressure compartments. Accurate velocity modeling and well tying using geostatistical methodologies are significantly advantageous, which will be essential for locating development wells and evaluating the size of the prospect and oil-water contact lines.

The above figure shows histograms of well miss-ties between two time-to-depth conversion methods. Purple bars show miss-ties from conventional time-to-depth conversion and blue bars show significantly improved ties from geostatistical methodologies of time-to-depth conversion.

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Case History 1: T2D - Offshore S. America
                           

 


SeisLink Corporation   4801 Woodway Drive, Houston, TX 77056      (281) 491-8877  info@seislink.com