OHIO OPERATORS SETTING SIGHTS ON OBJECTIVES IN CAMBRIAN, ORDOVICIAN

Feb. 4, 1991
G. Alan Petzet Exploration Editor Exploration for gas in rocks of Cambrian and Ordovician age is on the upswing as the Devonian Clinton and Medina tight gas sands play starts to wind down in the Ohio portion of the Appalachian basin. The area's intrepid independent operators refer to the objective formations as Ordovician Trempealeau dolomite, Rose Run sandstone, Copper Ridge dolomite, Knox dolomite, Beekmantown dolomite, and Cambrian Rome and Mount Simon sandstones. Rose Run drilling is
G. Alan Petzet
Exploration Editor

Exploration for gas in rocks of Cambrian and Ordovician age is on the upswing as the Devonian Clinton and Medina tight gas sands play starts to wind down in the Ohio portion of the Appalachian basin.

The area's intrepid independent operators refer to the objective formations as Ordovician Trempealeau dolomite, Rose Run sandstone, Copper Ridge dolomite, Knox dolomite, Beekmantown dolomite, and Cambrian Rome and Mount Simon sandstones.

Rose Run drilling is centered in Coshocton, Holmes, and Tuscarawas counties.

The formation underlies roughly the eastern half of the state and is the subject of a detailed U.S. Department of Energy funded geologic investigation by the Ohio Geological Survey, Columbus.

Various operators have placed the success ratio in Rose Run at 20-30%. Many of the discoveries are one well fields, and even though it is early in the play, several fields have grown to four to five wells.

PLAY GROWING

Operators in the area say the play is growing in terms of number of locations being staked.

Ohio has issued about 100 permits to drill to all of the deep formations since Oct. 1, 1990, including about 25 during the first half of January 1991.

Richard C. Poling, Somerset, Ohio, in November 1990 staked 1 Cockrell-Godshall Unit, a planned 5,000 ft Precambrian wildcat in Delaware County.

And Quest Energy Co., Dublin, Ohio, spotted 2 Hedges Lease, a 3,999 ft Knox wildcat about 1 mile north of the northern part of Mount Gilead field.

Chevron U.S.A. Inc., meanwhile, was to spud in late January the third of three wildcats in Marion and Wyandot counties. The first two were dry.

The wildcats, permitted to 2,200 ft or Knox were Ordovician Trenton-Black River oil tests, the company said. Chevron is coring the wells, which are on the Appalachian side of the crest of the Findlay arch.

Through the mid-1980s, Devonian age formations produced the largest shares of the Appalachian basin's cumulative oil and gas production, while Cambrian and Ordovician had yielded the smallest shares (OGJ, Aug. 12, 1985, p. 116).

RECENT EXPLORATION

Rose Run has been eastern Ohio's most permitted primary objective deep formation the past 4 months.

Jerry Moore Inc., Hartville, Ohio, completed 2-17 Yoder, in Clark Township, Holmes County, about 2 years ago for an open flow of 10 MMcfd of gas from Rose Run to help heat up the play.

Stone Resources & Energy Co., Worthington, Ohio, completed 7 Mizer, in Sec. 1 of Adams Township, Coshocton County, in an unnamed field in September 1990. It pumped 26 b/d of oil and 4 b/d of water with 775 Mcfd of gas from treated Beekmantown open hole at 6,826-76 ft.

And a well drilled in Mount Gilead field by Hortin & Huffman, Worthington, Ohio, attracted considerable attention in 1989, Petroleum Information points out. Completion rates were 103 b/d of oil and 1 MMcfd of gas from Trempealeau at 3,403-07 ft.

Other concentrations of permits issued the past 4 months to the various deep formations are in Wayne, Medina, Licking, and Muskingum counties.

The play is also beginning to grow in northwestern Pennsylvania (OGJ, Oct. 8, 1990, p. 129).

DEPTHS, COSTS

Drilling depths for the Cambrian and Ordovician zones and the share of total wells being drilled to these and the Clinton and Medina formations are pushing the Appalachian basin average well depth ever deeper.

Depths of the Cambrian and Ordovician formations range from 3,200-3,500 ft in Morrow and Richland counties, central Ohio, to 6,0007,000 ft in Tuscarawas and Guernsey counties further east.

The average well drilled in Petroleum Information's eight state Appalachian region was more than 4,000 ft deep in 1989, compared with about 3,100 ft during 1980.

One operator puts rotary drilling costs at about $7/ft for air drilled Rose Run tests. He estimates a completed Rose Run well, including seismic surveys, drilling, completion, and pipeline hookup, at roughly $150,000 drilled with air and $200,000 drilled with mud.

SIZING UP ROSE RUN

The Ohio Geological Survey is in the early stage of the 2 year study of the Rose Run in eastern Ohio.

Among the goals are to help the state assess and maximize recovery of its resources and assist independents that lack the time and money for such a detailed geological investigation.

Operators will be asked to donate seismic and other data for use in reservoir characterization and reserves estimation.

Rose Run reserves average perhaps 300-400 MMcf/well and range from 75-100 MMcf/well to about 1 bcf/well, estimates Luq Yacub, a petroleum engineer with Jerry Moore Inc.

The company's oldest Rose Run producing well is only about 2 years old.

Moore sells gas to Columbia Gas System Inc. and East Ohio Gas Co. at $2.30-2.70/Mcf, and the price and takes have been steady, Yacub said.

He believes Rose Run deliveries average about 300 Mcfd/well against about 250 psi line pressure, with a deliverability range of 100-500 Mcfd.

Initial pressures are about 2,350 psi.

Moore tries to reduce its exploratory risk by shooting two or three seismic lines to define drilling locations. Yacub feels the best completions are made in the Beekmantown interval.

Rose Run porosities average 8-12%, and net sand thickness is 60-70 ft in parts of Holmes County.

The western limit of the Rose Run subcrop lies roughly along a line extending from Ashtabula, the state's northeasternmost county, to nonproducing Brown County in southwestern Ohio.

ROSE RUN COMPLETIONS

Here are more examples of recent Rose Run completions across eastern Ohio:

Columbia Natural Resources Inc. in mid-1990 completed 22184 Hershberger, in Military Run field, Holmes County. It pumped 100 b/d of oil with 500 Mcfd of gas from Rose Run perforations at 5,876-5,988 ft.

Bill Blair Inc., New Springfield, Ohio, completed 5 Blickensderfer, in Homeworth field of Columbiana County in mid- 1 990. It flowed 200 Mcfd, natural, from Rose Run open hole at 8,078-8,234 ft.

Flow rate was the same at Equity Oil & Gas Funds, Elyria, Ohio, 1R Reeve, in an unnamed field in Ashtabula County. Rose Run produced from open hole at 6,130-38 ft.

In Baltic field of Holmes County, Lake Region Oil Co., Dalton, Ohio, completed 2 Raber, in Sec. 22 of Clark Township. Rose run perforations at 6,428-40 ft flowed 700 Mcfd of gas in late 1989. Total depth is 6,575 ft.

Cameron Bros., Zanesville, Ohio, opened Rose Run pay in Griffin field of Muskingum County at 1-R Johnston. It flowed 360 Mcfd of gas from perforations at 6,287-97 ft on completion last September.

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