--> Abstract: 3-D Time-to-Depth Conversion Beneath a Deep Marine Channel: Finding the Depth Error Model Using a Pragmatic Approach, by R. W. Jeffery and D. R. Jefferis; #90920 (1999).
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JEFFERY, ROBERT W., Forcenergy Inc., Anchorage, AK; and DAVID R. JEFFERIS, Dynamic Graphics Inc., Bakersfield, CA

Abstract: Previous Hit3-DNext Hit Time-to-Depth Conversion Beneath a Deep Marine Channel: Finding the Depth Error Model Using a Pragmatic Approach

From a work flow point of view, a Previous Hit3-DNext Hit geologic model of an exploration prospect in Cook Inlet, Alaska was initially interpreted in time-domain using a Previous Hit3-DNext Hit seismic interpretation system, then assembled into a Previous Hit3-DNext Hit geologic model in time, reviewed, revised, and vertically rescaled to depth-domain using a Previous Hit3-DNext Hit geological modeling system.

Following the assemblage into a Previous Hit3-DNext Hit geologic framework in time-domain, the results of the interpretation were verified against the working conceptual model of the geophysicist as being reasonable. Since only a single checkshot survey was available, and a deep marine channel was directly above the prospect, the project geophysicist knew that the Previous Hit3-DNext Hit average velocity model could not possibly honor reality. A "back-of-the-envelope" calculation predicted the amount of error that would be realized from applying a single linear velocity function over the Previous Hit3-DNext Hit space. This calculation took into consideration the location of the checkshot survey, channel geometry, and geologic structure of the prospect.

Once the geological model was in depth, an error analysis was performed using the few wells that had been drilled in the area. Using various 2-D gridding algorithms and Previous Hit3-DNext Hit visualization, the different error models were reviewed to find one that matched the error model developed by the project geophysicist. It became apparent that the best solution would be to use the geostatistical technique of kriging with an external drift; using the channel bathymetry as the external drift. This error model was then applied to the depth model to derive the final Previous Hit3-DTop geological model.

AAPG Search and Discovery Article #90920©1999 AAPG Pacific Section Meeting, Monterey, California