Reconstruction of Paleoenvironments Through Integrative Sedimentology and Ichnology From Core and Formation Micro-Imager (FMI) Logs in the Kinder Morgan Katz Field Unit, North Central Texas

Abstract

Four cores and 14 image logs from the Strawn Formation in the Kinder Morgan Katz Field Unit and adjacent Orsborne Field were logged with particular attention given to identifying lithofacies. Direct comparisons between physical core and image logs were used to produce a borehole image lithofacies catalog for the Katz Field Unit (lithofacies A through L). Combined lithofacies identified in core and image logs include: A) mudstone to bioturbated mudstone; B) parallel laminated to bioturbated sandstone to shaley sandstone; C) flaser- to lenticular- to wavy-bedded sandstone and mudstone; D) heavily bioturbated sandstone; E) ripple-laminated to trough cross-stratified sandstone; F) ripple-laminated to herringbone cross-stratified sandstone; G) cross-bedded sandstone; H) interbedded sandstone and limestone; I) wavy- to parallel-bedded limestone; J) cross-bedded limestone; K) diagenetic-nodular and/or brecciated limestone; and L) interbedded limestone and shale. Accessories commonly associated with lithofacies in both core and Formation Micro-Imager (FMI) include: bioturbation, carbonate bioclasts, carbonate breccias, carbonate cement, plant debris, siderite nodules, slumps and contorted bedding, microfaults, mud balls, and mud rip-up clasts. Core and image log lithofacies associated with a combination of Skolithos, Cruziana, mixed Skolithos-Cruziana, and rare Zoophycus ichnofacies identified in the cores suggest that paleoenvironments of the Katz Field include a bayhead delta, back-barrier estuary-embayment, flood tidal delta, tidal flat, and upper to middle shoreface. Trace fossils include Asterosoma, Diplocraterion, Chondrites, Conichnus, Cosmorhaphe, Cylindrichnus, Helminthopsis, Phycosiphon, Rhizocorallium, Rosellia, Skolithos, Teichichnus, and Zoophycus. Conodonts collected from crinoid-bryozoan-brachiopod wackestone-packstones in two cores include age-diagnostic species (Neognathodus expansus and Gondolella pohi, Idiognathodus aff. I delicates) indicate a mid Desmoinesian age. The integration and interpretation of the Katz Field Unit core data, image log lithofacies, and ichnofacies help to guide the propagation of lithofacies to a larger area within the unit leading to a clearer understanding of the distribution of flow units between wells, both horizontally and vertically at depth. This assists in correlation of lithofacies geometries, supporting our current conceptual reservoir model and identification of pay zones and flow barriers.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015