--> ABSTRACT: Well-cuttings Based Three Dimensional Model For Subsurface Mississippian Greenbrier Group, West Virginia, by Thomas C. Wynn and J. Fred Read; #90906(2001)

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Thomas C. Wynn1, J. Fred Read1

(1) Virginia Tech, Blacksburg, VA

ABSTRACT: Well-cuttings Based Three Dimensional Model For Subsurface Mississippian Greenbrier Group, West Virginia

The 50 to 500m thick mixed carbonate-siliciclastic Mississippian Greenbrier Group (Big Lime and Little Lime) West Virginia contains significant petroleum reservoirs, but little is known concerning the sequence stratigraphy in the subsurface, their trends and stacking patterns or the relationship of reservoirs. This has impeded the systematic exploration for these targets. High-resolution sequence stratigraphy of the Greenbrier Group is being done throughout the subsurface in West Virginia, using well-cuttings (200 wells) and wireline logs. A series of detailed regional cross-sections and isopachs of time slices are being prepared to better understand these trends.

Five major sequences occur composed of two to five regionally mappable high frequency sequences (HFS's). Major- and high frequency sequences are composed of lowstand red beds up-dip and shallow marine sands along the ramp margin, semi-transgressive shale's, high-stand quartz peloidal grainstone (dominantly eolian), peritidal lime mudstone, peloid grainstone, ooid grainstone, skeletal grainstone, open marine skeletal wackestone/mudstone, and shaly slope mudstone. Sequence boundaries are placed below lowstand sands, red beds, caliches and/or eolianites.

Isopachs of selected time show subtle regional tectonic features. A subtle regional linear tectonic high is evident along the ramp margin in the vicinity of the basinal hinge line. This hinge separates the relatively stable up-dip sections from the faster subsiding basin. Thickness trends strongly reflect tectonically induced basinal subsidence. Subsidence rates in the up-dip and downdip areas differ by an order of magnitude, yet the eustatic signal, which formed the 3rd order sequences and the HFS's is traceable from the Appalachian Basin into the Illinois Basin.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado