Joint Meeting: University of Wyoming Department of Geology and Geophysics Wyoming Geological Association Geological Survey of Wyoming: April 2-4, 1982 Laramie, Wyoming: Subsurface Practices in Geology and Geophysics Abstracts of Papers - Compiled by James R. Steidtmann

Porosity destruction, preservation, and enhancement in cratonic, sublitharenitic sandstones of the Desmoinesian Cherokee Group in southeastern Kansas are related to stages of diagenetic alteration which preceded hydrocarbon emplacement. Thin-section and scanning-electron microscopy of subsurface samples reveal three stages of diagenesis. Stage 1 is rare, local concretions of spherulitic siderite and calcite cement. Stage 2 is extensive chloritic grain coatings, euhedral to interlocking overgrowths, and rare feldspar overgrowths. Stage 3 is patchy cementation by dolomite-ankerite, siderite, and kaolinite accompanied by feldspar dissolution and replacement.

Stage 1 cements were precipitated during early compaction and locally have destroyed all available porosity and permeability. Porosity preservation occurred during stage 2 diagenesis, where chloritic grain coatings inhibited subsequent cementation. During stage 3 diagenesis, dissolution of feldspars enhanced original porosity while kaolinite cementation altered original and secondary macropores to micropores. Emplacement of hydrocarbons halted further diagenetic alterations in sandstones.