EnerVest Happy With Clinton Sandstone Horizontal Wells in Ohio

By Bob Downing

A Texas-based company is pleased with its initial results in drilling horizontal wells for oil in the often-drilled Clinton Sandstone in Stark and two other counties.

The results from the shallow rock formation look promising, although EnerVest Operating LLC is still fine-tuning the drilling, said Barry Lay, senior vice president and general manager of the company’s Appalachian North Asset Team.

The company has completed seven smaller experimental wells in the Clinton Sandstone, he said on Thursday at the Ohio Oil and Gas Association’s three-day winter meeting in Columbus. Five of the wells are in Stark County, and one each in Carroll and Tuscarawas counties.

Those horizontal wells are producing more than vertical-only wells, and that’s good news, he said.

Serious drilling in the Clinton Sandstone is unlikely until commodity prices rise, he said. Company executives, however, “still believe that Clinton drilling is a good option,” he said.

The new wells, with 2,000-foot laterals, each cost about $1.8 million and each could produce an estimated $7 million to $10 million in revenue, Lay said. The $1.8 million cost is far more than the $400,000 it costs to drill a vertical-only well, he said.

That revenue is a huge increase from the $1 million typically derived from vertical-only wells in the Clinton Sandstone, he said in the company’s most-detailed report about the drilling that was announced in 2014.

Some see the Clinton Sandstone as being a new source of income for Ohio drillers and landowners. The new horizontal wells could help small drillers unable to fund expensive Utica Shale drilling to tap into a new Ohio energy source.

Clinton sandstone is found under 25 counties in eastern Ohio including those in the Akron-Canton-Cleveland area and it has been drilled for 100 years. The wells have been straight vertical holes into the formation that is 3,000 to 4,600 feet below the surface.

Ohio already has about 63,000 producing wells, more than half tapping Clinton sandstone. Three-fourths of the oil and gas produced in Ohio from 1985-2009 came from Clinton, according to the Ohio Oil and Gas Association.

EnerVest Operating, part of Houston-based EnerVest Ltd., saw the horizontal wells as a new way to tap into the Clinton Sandstone and decided to test its plan in what’s called the East Canton Well Field where large quantities of oil remain underground, despite heavy drilling.

The field was discovered in 1947 and has about 3,000 active wells on 214,000 acres. The area is believed to be home to 1.5 billion barrels of oil. An estimated 105 million barrels of oil have been recovered but estimates are that 93 percent of the oil remains underground.

The East Canton Well Field covers eastern Stark County and extends into Carroll, Tuscarawas and Harrison counties. EnerVest has about 115,000 leased acres and 1,700 vertical wells in the area.

The shallow horizontal wells can be drilled in 20 to 25 days, although his company has encountered problems in drilling its seven wells, Lay said. The rock is especially hard and has broken countless bits during drilling, he said.

That $1.8 million drilling cost is far less than it would cost to drill a larger horizontal well in the Utica Shale in eastern Ohio where such wells cost from $6 million to $10 million.

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Trying to keep an eye on this (Clinton strata) part of the modern long bore horizontal well development myself.

Thanks for posting Barry D.

Barry D-

Drill bit technology has evolved many fold in recent decades. Long gone are the days where a drill contractor "drills the cones off of the bit". I wonder if EnerVest is using some of the more modern bits/cutting devices that have been tried elsewhere with great success, or are they still using old school rotary tri-cone technology?

Just curious, the wheel does not have to be re-invented for each play type.


Good piece - it is for this type of information that I check this site from time to time.  

Brian Powers, I think I asked you this years ago, but in your view, this same approach could maybe be used in thinner Berea formations as well...like as thin as 30 feet pay zones?

Markus - Good to hear from you. 30 ft vertically thick pay zones can be successfully horizontally drilled. Many operators drilled very thin pay zones in the Austin Chalk in central Texas in the mid 90's. I'll grant you that chalk (essentially limestone) is usually softer and easier to drill than sandstone. Two factors come to mind: first, is there enough offset well control (offset penetrations to ascertain bed thickness at the target location? Secondly, does the Berea contain hard streaks or similar  geologic characteristics that would greatly reduce bit or cutter life, such as pyrite or chert nodules  in the case of chalk?

The Soviets made great strides in horizontal drilling technology in the 1980's and '90's; Western operators have improved upon these strides in succeeding decades. Thin pay zones can be accessed with modern tools and techniques.


Brian, Markus,

I would believe in certain areas, in Ohio, there is plenty of offset information.

I also wonder how much oil/gas will be produced from these horizontals in previously produced areas?

In reference to the article, it indicates that only about 10% of the oil  has been recovered from a highly drilled area.

It appears that if economically successful it could open up a whole new area of exploration.

Just a thought, Barry D:  Remember that the Permian Basin is one of the oldest producing regions in the States and believed by some to be on its last legs.  Now, it is again once more a top-producing area due to better technology e.g. horizontal drilling into six or seven stacked layers, enhanced oil recovery like with CO2, longer laterals, more stages, more proppant, etc.  EOG is especially good at all of this.  Michael Filoon of Seeking Alpha has excellent background on all this.  I highly recommend that you devote quite a bit of time to reading his analyses.



I wonder if this approach could make the Clinton economical in areas where production has been poor or marginal?

If so, we have a whole new play to watch.

Good for landowners.

A modern technology and a very familiar sandstone may hold new riches for Ohioans.

Horizontal drilling is being used in Stark County by one Texas-based drilling company to access natural gas and oil in the Clinton sandstone and to boost production.

EnerVest Ltd., based in Houston, has quietly drilled seven miniaturized horizontal wells in the sandstone that has been heavily drilled in the past.

Clinton sandstone is found under 25 counties in eastern Ohio including those in the Akron-Canton-Cleveland area.

EnerVest has drilled three wells in Nimishillen Township. Two are in Washington Township and one each is in Bethlehem and Marlboro townships, according to state records.

An eighth well, south of Canton in Pike Township, has been approved by the Ohio Department of Natural Resources’ Division of Oil & Gas Resource Management. It has not yet been drilled, according to state records.

The company on Aug. 5 filed to drill a ninth horizontal well. It will be in Nimishillen Township.

Two of the EnerVest wells had deeper wells that were plugged back to permit the shallower horizontal drilling, said ODNR spokesman Mark Bruce.

It will be at least 90 days before EnerVest can determine how successful the new horizontal wells might be, said company spokesman Ron Whitmire.

The company’s Clinton’s initiative is new, started in the last few months, he said. "We’re in the very early stages."

The results from the new wells will determine whether EnerVest expands the Clinton drilling, Whitmire said.

EnerVest has drilled wells in the Utica shale by itself and with partners Chesapeake Energy Corp. and Total, the French energy giant.

The goal is to see if "today’s technology will work in this play," he said.

The Clinton wells would go down about 4,600 feet to reach the sandstone. The wells’ laterals or horizontal legs would be about 1,500 feet in length, according to experts.

That is shorter than the much publicized horizontal wells being drilled in Carroll, Harrison, Belmont, Guernsey, Monroe, Noble and Washington counties. Those wells in the Utica shale have multiple laterals that may extend outward two miles or more.

The new wells would be far cheaper: perhaps $1 million to $3 million per well, compared to $6 million to $11 million per well in the Utica shale.

That will create a new financial opportunity for Ohio’s smaller drilling companies and landowners, said Shawn Bennett of Energy in Depth-Ohio, a pro-drilling trade group.

"It’s a great opportunity and we hope they are very successful," he said of the new wells.

The risk is that all rocks are different, he said. He asked: Will the Utica technology transfer to the Clinton drilling successfully? "We don’t know yet if it will work or if it will be profitable," he said.

In tapping the sandstone, the drillers are going after resource rocks, not source rocks like the Utica shale, he said.

The Ohio Oil and Gas Association, a statewide trade group, is very supportive of the new drilling efforts, said spokesman Mike Chadsey.

It is an opportunity for Ohio’s small independent oil and gas producers "to get off the sidelines and back in the game," he said.

Those companies have largely been unable to take advantage of the more costly Utica shale drilling that erupted in eastern Ohio in mid-2010, he said.

Ohio is not the first state where drillers are starting to look beyond the Utica and Marcellus shales, said Dr. Robert Chase, professor and chair of the Department of Petroleum Engineering and Geology at Marietta College.

Drillers in Pennsylvania and Kentucky have both started drilling into shallower sandstones, he said.

"From what I can see, there’s no real risk," he said. "The potential impacts for drillers and for landowners could be really big."

Drilling horizontal wells in the Clinton sandstone could boost production and provide bigger payments for landowners and drillers, he said.

Landowners could see significantly more revenue from increased production, if the new horizontal wells are successful, he said.

Going after the gas and liquids in the Clinton sandstone will be challenging, Chase said.

A great many wells have been drilled into that formation over the years, and the key will be find localized pockets that not been tapped in the past, he said.

The companies trying to drill in the Clinton sandstone will likely do extensive research to find areas that have been only lightly drilled, he said.

For that reason, the Clinton drilling will likely be very localized, he said.

The drillers will likely need smaller leased tracts to drill such wells, perhaps 80 to 120 acres per well, depending on the length of the laterals, Chase said.

Hydraulically fracturing or fracking the Clinton sandstone would require far less water than is needed to frack the Utica shale, Bennett said.

Water, sand and certain chemicals are pumped into the underground wells under pressure to crack the rock and enable drillers to reach the natural gas and liquids

Chase said he sees no major risk to ground water with the wells being designed with cement and steel casings that would boost water protection.

Others are less sure. Paul Feezel of the Carroll Concerned Citizens in Carroll County said he is worried that faults in the underground rocks and even old wells in the Clinton might provide pathways for drilling contaminants to reach ground water.

The new sandstone wells are significantly closer to the ground water than the deeper Utica shale wells in eastern Ohio, he said.

The potential threat to ground water from the new wells is "a slippery slope…and a concern, in my mind," Feezel said.

Ohio has about 63,000 producing wells, more than half tapping into the Clinton sandstone. Three fourths of the oil and gas produced in Ohio from 1985-2009 came from Clinton sandstone wells, according to Ohio Oil and Gas Association.

The Clinton sandstone has been extensively drilled at least three times in Ohio, most recently in the 1970s and 1980s


For the fractivists, most if not all, Clinton wells have been hydraulically fractured.

Further, the surface casing has been cemented through the water tables.

Look it up.

Is it possible that the integrity of some older wells may be a problem ? Yes. But there is no wide spread danger to ground water here.

So for hysterical fractivists I suggest you take a pill.

A further thought,

Hydraulic fracturing has been employed in development of oil and gas wells for over 68 years.

Not once, I repeat not once has hydraulic fracturing contaminated ground water, Never!

The fractivists may claim that horizontal drilling combined with hydraulic fracturing is more dangerous. Once again. not true. Tens of thousands of horizontal wells have been "fracked" not one incidence of ground water contamination.

Mr, Feezle's implication that work such as Enervest's could be dangerous to ground water is unfounded and simply fear mongering.

My thoughts exactly, Barry D!  If there were any harm done to drinking water aquifers due to drilling into "shallow" Clinton formations since the 70s, wouldn't we have known about it by now?


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