ABSTRACT

The East Randolph Rose Run field is located in Randolph Township, Portage County, Ohio. The field was discovered in 1992 as a down dip extension of the Randolph Gas field discovered by Belden & Blake Corporation a year earlier. Since its discovery, over 40 wells have been drilled in the East Randolph field that have produced an estimated 600,000 barrels of oil and 1.5 billion cubic feet of gas.

Characterization of the productive upper Rose Run sandstone members is underway to determine the technical and economic feasibility of water flooding, gas pressure maintenance, or the possibility of infill drilling for oil in the East Randolph field. Core data and log data for each sandstone member was analyzed and mapped to determine their relationship with estimated ultimate recovery of oil and gas.

The upper Rose Run sandstone can be divided into four distinct sandstone units characterized by bedding, mineralogy and log character. Each of the four sandstone units usually represents a fining-upward cycle of sandstone, sandy dolomite and dolomite. The uppermost unit (#1) consists of tightly cemented sandstone with quartz overgrowths, low permeability and low porosity, while the lowermost sandstone unit (#3B) is usually the most permeable (1.5 - 12.9 md) and porous (2.6 - 11.2 percent). This variation in porosity and permeability is predominantly controlled by grain size, amount and type of intergranular cement, and extent of secondary dissolution porosity. Most of the East Randolph field's oil production can be attributed to the reservoir development of the Rose Run #3A and #3B units. Gas production appears to be present in all four units, but seems to be best when good reservoir development is found in the #1 and #2 sandstone intervals. Volumetric calculations using new geologic models increase estimates of the amount of original oil-in-place at over 10 million stock tank barrels, more than double the initial estimates. The new geologic model will be used as input for reservoir simulation to optimize future locations of infill wells, and determine waterflood and/or pressure maintenance feasibility.