Advances in Diplog® Data Processing for Stratigraphic Analysis

Abstract

Detailed log-derived stratigraphic interpretation requires the use of high vertical resolution logging devices such as a dipmeter. The Dresser Atlas Strata Dip® program, originally intro­ duced in the early 1980's, is a computer program designed to give a detailed point-wise estimate of the orientation and depth of very fme formation laminae. Numerous improvements in the computational algorithms coupled with features such as the removal of the effects of structural dip and intelligent handling of floating pad data have resulted in a second generation product which is described in this paper. The accuracy of the program's results was tested using synthetic data generated by a dip simu­ lation program. The repeatability of the program (in fact of the entire data acquisition and processing system) is demonstrated by separate analyses of three independent runs over the same well interval. Two field examples demonstrate the value of this new program as an aid to stratigraphic analysis. Since its introduction in the early 1980s, numerous improvements in the program have resulted in a second generation product. A description of the program logic is given so that others may gain a greater understanding of the correlation technique employed. While this technique is an intuitively valid approach to detailed dip .analysis, experiments were conducted to verify its application in practice. The first of these experiments demonstrates the accuracy of the program in estimating the location and orientation of bedding planes traversed by the borehole. The second experiment demonstrates the repeatability of the entire Diplog® system which comprises both data acquisition and Strata Dip processing. The usefulness of the program as an aid to stratigraphic analysis is shown via two field examples. The first of these examples is an eolian dune analysis in which the program clearly indicates the individual dune sets and the paleo-wind directions. The second example is an analysis of a sandstone formation comprising sediments deposited in a fluvial environment. This formation is interpreted as a point bar sequence consisting of channel lag, trough cross set, and ripple cross laminae deposits.