Abstract: Subsurface Geology of the Washington Field in Washington Township, Tuscarawas County, Ohio
THOMAS, ROBERT B.
Eastern Mountain Fuel, Inc., Parkersburg, WV
Production in the Washington Field is from the Lower Ordovician Beekmantown Dolomite, B porosity zone. The Beekmantown B is located between 145 and 175 ft above the top of the Rose Run Sandstone. Beekmantown B porosity is secondary porosity related to karst aquifer development at the time of the Post-Knox Unconformity. Average Beekmantown thickness of the producing wells in the Washington Field is 182 ft. The minimum and maximum Beekmantown thickness in producing wells is 152 and 202 ft, respectively.
Average thickness of the Glenwood Shale for the producers in the Washington Field is 69 ft with a range of 50 to 80 ft. This goes against conventional models of Rose Run and Trempeleau exploration where thinner Glenwood is expected for a productive well. Dry holes in the field average 88 ft of Glenwood.
Structure maps on the top of the Rose Run Sandstone indicate that higher porosity in the Beekmantown B is associated with the preUnconformity structural lows and the flanks of the lows. The structural lows coincide with the avenues of drainage for water at the time of the Post-Knox Unconformity. Wells on top of pre-Unconformity structures may have Beekmantown B present, however, secondary porosity development is limited.The geologic evidence points to a specific geologic landform where the Beekmantown B porosity has sufficient porosity and connectivity to be productive. This landform is a preserved valley floor with an associated karst aquifer system which was controlled by pre-Unconformity structure.
AAPG Search and Discovery Article #90930©1998 AAPG Eastern Section, Columbus, Ohio