--> Abstract: A Method of Constructing Chronostratigraphic Diagrams (Wheeler Diagrams) from Well Logs: An Example from the San Juan Basin, New Mexico, by J. W. Robinson and D. W. Valasek; #91004 (1991)

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A Method of Constructing Chronostratigraphic Diagrams (Wheeler Diagrams) from Well Logs: An Example from the San Juan Basin, New Mexico

ROBINSON, JOHN W., and DAVID W. VALASEK, Colorado School of Mines, Golden, CO

Conversion of a well log section into a chronostratigraphic diagram can be one of the most important steps an explorationist can take in understanding complex interrelationships of time and space on the geologic record. To this end, a method has been devised that allows a simple check of the degree to which chronostratigraphy has been employed. A depositional dip well log section is constructed using a datum horizon correlated along the section that represents an approximate regional time significant surface. Detailed correlation of third-order to fourth-order progradational cycles used in this example portrays a regressive to transgressive depositional sequence, but the methodology employed should function properly at all scales. An interpretation of facies distribution of individual time-bounded units is constructed on an overlay of the original log section. Finally, a graphical depiction of the time/space domain is generated by sequentially transferring the lithostratigraphic interpretation onto a Wheeler Diagram with each progradational cycle hung from its top time boundary. If the proper chronostratigraphic framework was employed, facies will rise as you shift basinward along the section. If the facies do not rise, alternative correlations must be made or alternative interpretations of facies architecture must be considered. An example is given from the Gallup Sandstone (Coniacian) of the San Juan basin, New Mexico.

 

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)