Computer Modeling of Balanced Sections in Exploration

A. Gibbs, A. Bell, J. Wheeler

Balanced sections are a powerful way of testing the geological validity of structural interpretations derived from well, seismic, or field data. The geometric elements drawn on the interpreted section must be sufficient to allow a complete palinspastic restoration. Sections and, hence, maps that cannot be balanced are geologically invalid and inevitably lead to mistakes in sitting on exploration or production wells. Balanced section analysis involves the interactive process of restoration and modification with accurate redrafting of the section at each step. By hand, this process normally takes so long for all but the simplest sections that it is not done or at best is done on a single section.

Interactive computer techniques have been developed that allow this analysis to be done routinely as a way of checking interpretations in both thrust belts and basins. Stepwise restoration and section editing is used to check correlations across fault zones and to predict accurately the position and geometry of formations. The effect of progressive compaction during fault growth shows how trap formation occurs by the interplay of tectonics and sedimentation. This paper outlines the technique and discusses case histories where the technique has been successfully used to elucidate geological history and structure. Particular attention is given to balanced palinspastic restoration as a predictive tool and in specific cases minimizing risk in the interpretation of prospects in areas of co plex structure.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.