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The AAPG/Datapages Combined Publications Database

North Dakota Geological Society

Abstract

NDGS-AAPG

Symposium on the Geology of Rocky Mountain Coal, October 2-4, 1984

Pages 126 - 136

AMENDMENT OF INCOMPLETE STRATIGRAPHIC DATA AS AN AID TO INTERPRETING AND MODELING DISCONTINUOUS SEAMS IN MULTI-SEAM DEPOSITS

R. Dean Willis, H. Warren Taylor

Control Data Corporation, Mineral Systems Division, Golden, Colorado 80401

ABSTRACT

Drilling programs in bedded deposits yield stratigraphic information which is incomplete compared to the ideal situation of being able to consistently sample all horizons in every borehole. Correlatable strata can pinchout, outcrop, subcrop, split, undergo facies changes, or can be washed out, burned, or weathered. Additionally, adjacent holes are often drilled to significantly different depths and do not intersect all correlatable units. All of these occurrences contribute to incomplete sampling of correlatable strata and result in inherent modeling problems.

A suite of computer programs has been developed to complete data sets and prepare the data for modeling. The system's simple interpolation technique uses interburden relationships in neighboring boreholes to insert horizons where seams are missing. The system yields a data set with either interpreted stratigraphic horizons or original coded data present for all correlated strata in each borehole of the data set. Use of the amendment program can be iterative since the inserted horizons can suggest alternate interpretations for previously correlated horizons in source documents. An important facet of the amendment system is the use of thickness for the inserted horizons. A geologic interpretation (washout, pinchout, etc.) of the inserted horizons must be made. The system establishes a set of codes as a base interpretation which is validated using cross sections and plan maps. The codes (which may be modified) ultimately determine how the inserted data affect thickness during modeling.

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