Industry veterans didn鈥檛 believe Bob Eagle when he told them about the horizontal Strawn wells his company was drilling on the Eastern Shelf of the Permian Basin.
鈥淭hey鈥檇 say, 鈥楴o you鈥檙e not,鈥� Eagle told Hart Energy. 鈥淵ou鈥檙e not in the Strawn, you鈥檙e in the Cline or the Wolfcamp shale.鈥欌€�
The Strawn Formation was already well-known to Eagle, president of Clear Fork Inc. of Abilene, Texas, and oilmen like him on the Eastern Shelf. Vertical oil production from the Strawn interval dates to 1920, according to state historical records.
鈥淲e鈥檝e all drilled through it or for it our whole careers,鈥� said Eagle, who has operated Clear Fork on the Eastern Shelf since 1981.
But it was the horizontal development of the Strawn sands starting in 2015 that kicked off a frenzy of new investment, leasing and drilling activity in the area.
鈥淧art of that is a lot of the old timers in Midland just didn鈥檛 believe these results could be happening on the Eastern Shelf,鈥� Eagle said.
Nearly a decade later, Clear Fork ranks among the top oil producers on the Shelf, after drilling or participating in about 60 horizontal wells.
Clear Fork and other operators have learned much about the Strawn sands鈥攁nd the challenging variability drilling the interval across the play鈥攐ver that period.
Operators leased up thousands of acres of country when the horizontal play was first taking off. But a near-decade of delineation has proven that the play isn鈥檛 as prospective as the independents first believed. Clear Fork has let 鈥渁 lot of those acres expire鈥� over time, Eagle said.
Horizontal development of the Eastern Shelf is too big a job for the smallest family-owned operators, and it鈥檚 too small a play to pique the interest of the publics and majors.
A few publics, including Devon Energy, were active in the area in the mid-2010s when the Cline shale was a hot topic. But most publics have focused their investment on the Permian鈥檚 Wolfcamp, Spraberry and Bone Spring formations in recent years.
Independents like the Eastern Shelf Strawn play because of the competitive well economics. The Strawn wells are drilled to shallower depths than the deeper Midland Basin wells. Producers also don鈥檛 need to frac the Strawn sands as hard as Midland producers do with the tight shale rock.
So, the Eastern Shelf emerged as a sort of 鈥渋ndependent paradise in that regard,鈥� Eagle said.
鈥淏ut I would say there鈥檚 a fine line between paradise and a graveyard,鈥� he added. 鈥淢ost people would say it鈥檚 a graveyard, but that鈥檚 what makes it interesting.鈥�
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Dreaming of Dessie
Chris Graham, president and CEO of Verado Energy, remembers well the Eastern Shelf鈥檚 leasing frenzy last decade. He helped kick it off.
Graham joined Allen, Texas-based Verado in 2013. Before that point, the company had primarily developed gassy conventional assets in the East Texas Oak Hill Field.
Verado was looking for opportunity outside of East Texas when Graham was introduced to King Operating at an industry conference. King Operating had acreage and vertical Strawn wells on the Eastern Shelf鈥攂ut the company was looking to boost production, Graham recalled.
The two producers discussed Verado鈥檚 experience fracking legacy vertical wells at Oak Hill and pondered how similar techniques could be applied to Eastern Shelf wells.
鈥淲e decided it鈥檚 not a good idea to frac the whole wellbore and try to get as many zones comingled at once,鈥� Graham said. 鈥淏ut since you know the Strawn鈥檚 producing, it looks like it鈥檚 got some characteristics where we said, 鈥楲et鈥檚 go horizontal on this.鈥欌€�
With King as operator and Verado as a non-operated interest holder, the companies completed the Dessie 91 #1H well in Scurry County鈥攏ear the town of Hermleigh, Texas鈥攊n August 2015, Texas Railroad Commission (RRC) filings show.
鈥淚t came in phenomenally, especially for a half-length horizontal well,鈥� Graham said. 鈥淎fter seeing the results on that, we said, 鈥楲et鈥檚 drill a full-length one.鈥欌€�
Verado and King teamed up on a second well, the Kate 143 Unit #1H, which went to sales in 2016. Impressed by its performance, too, Verado bought out King鈥檚 interest and took operatorship of the Hermleigh assets.
鈥淲e finished up that third well and we just kept going from there,鈥� Graham said.
Verado has produced nearly 3.8 MMbbl from Scurry County since the start of 2015, per RRC data. The company has drilled 16 horizontal wells since entering the Eastern Shelf, Graham said.
But growth hasn鈥檛 come without challenges. Verado and every other operator of substance on the Eastern Shelf have described subsurface complexity and variability across the play.
鈥淎s you expand out, there鈥檚 variability,鈥� Graham said. 鈥淭here鈥檚 different segments and benches鈥攖he Strawn B or Strawn C or Strawn A, depending on how you define them.鈥�
Wells tend to be deeper to the eastern side of the play. Water cuts will change from location to location. There鈥檚 heightened risk and uncertainty on the outskirts of the play, where reservoir characteristics are less defined.
鈥淪ometimes it works out really well, and sometimes you get some surprises as you鈥檙e drilling,鈥� Graham said.
Verado still has room left in Scurry County to drill a handful of additional locations, he said. Some of those locations are to the west of its acreage, where the shelf will dip down, or prograde, into the deeper Midland Basin.
A few future locations are to the north of Verado鈥檚 acreage, where Graham said reservoir characteristics can be a bit different. Verado鈥檚 latest project鈥擷ray #1H, completed in early 2023鈥攊s sited to the north of its acreage block.
Two years ago, Graham formed Corvus Resources, the next iteration of the Verado team, to hunt for acquisitions in areas with greater future upside.
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Clear Fork
Clear Fork has drilled conventional, shallow sands and limestones on the Eastern Shelf for decades. In late 2012, the company was producing around 1,000 bbl/d, watching as Permian shale players started to apply unconventional drilling techniques to the conventional reservoirs on the Shelf.
But it was the company鈥檚 horizontal Strawn wells鈥攖he largest drilling projects in Clear Fork鈥檚 history, Eagle said鈥攖hat took production to the next level.
Clear Fork completed its first Strawn horizontal in Fisher County in July 2018, RRC filings show. The well was drilled just a few miles over the county line from Dessie 91 #1H, Verado鈥檚 half-lateral horizontal that kicked off the play in 2015.
The company was pumping about 1,400 bbl/d by the end of 2018. Oil production had grown to over 3,600 bbl/d by year-end 2019.
By August 2022, and after drilling over 40 horizontals in the Hermleigh play, Clear Fork鈥檚 oil production peaked at nearly 10,000 bbl/d, records show; gas output averaged 20.5 MMcf/d that month.
Since the play started in 2015, Clear Fork has been the top oil producer in Fisher County and the fifth-largest producer in Scurry County (behind Occidental Petroleum and Kinder Morgan Production Co., operators of legacy conventional assets in the area).
Clear Fork, like most of the Eastern Shelf鈥檚 top producers, focused its efforts in and around the core of the Hermleigh Field spanning the Scurry-Fisher county line.
Since delineating the Hermleigh Field, Clear Fork and a smattering of other operators have pushed further east into Fisher County, near the town of Sylvester, Texas.
鈥淵ou have the Hermleigh proper and then the Sylvester area, which is where the activity is right now,鈥� Eagle said.
Nearby operators include Cholla Petroleum, Browning Oil Co. and Walsh & Watts Inc.
Clear Fork went forward with a handful of horizontals in the Sylvester development area, but they 鈥渉ave not been good performers.鈥�
鈥淎lthough it had the same characteristics, it just wasn鈥檛 the same as the Hermleigh proper,鈥� he said. 鈥淭he geology was a little bit more complicated.鈥�
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M&A challenges
The Midland Basin to the west is awash in M&A. The Eastern Shelf has seen relatively little dealmaking.
In 2019, Mid-Con Energy Partners LP sold most of its Eastern Shelf property to Scout Energy Group IV for $60 million, in counties north, east and south of Scurry.
Last year, Clear Fork sold its flagship asset in the Hermleigh Field to Austin-based Legacy Star Capital Partners for an undisclosed price.
Legacy Star acquired 100% of the Hermleigh asset through a newly launched platform company, Peak 10 Hermleigh LP. Peak 10 operates the Scurry County asset jointly with Browning Oil Co.
Clear Fork continues to operate acreage and Strawn wells in the Sylvester area of Fisher County, Eagle said.
By and large, well variability and a lack of multizone upside has made dealmaking challenging on the Eastern Shelf.
鈥淲e can鈥檛 sell anything,鈥� said Gideon Powell, CEO of Dallas-based Cholla Petroleum鈥攁nother top Eastern Shelf producer. 鈥淣o one鈥檚 going to give any value to the upside because we can鈥檛 even internally explain why it works sometimes.鈥�
The Permian is popular with big shale producers because of its lower risk profile. It鈥檚 almost a guarantee you鈥檒l strike oil in the Midland Basin because there are so many zones to attack: the Spraberry and Wolfcamp intervals, the Dean, the San Andres and more.
An Eastern Shelf producer might be able to land a lateral in a single zone. At most, you might find two producing benches, Eagle said.
And even when subsurface characteristics look promising, well results have varied rather inexplicably across the shelf.
鈥淚t鈥檚 a prograding shelf edge, so trying to draw a correlation from a well one mile away is sometimes impossible,鈥� Powell said.
鈥淲e鈥檝e got two horizontal dry holes鈥攖hat is not something that a lot of companies can stomach,鈥� he said.
Moriah Energy Investments, through its operating arm Moriah Operating LLC, has been one of the Eastern Shelf鈥檚 top producers over the past nine years.
Moriah has been active on the shelf since 2015 but started a new leasing effort the next year, spudding its first horizontal in 2018, Moriah President Tyler Harris said.
He also agreed: Subsurface variability is a real thing and does make it difficult to replicate results across the shelf.
鈥淥perators need to take a statistical view to well results,鈥� he said. 鈥淚ndividual wells may vary significantly from the field mean and I would expect that smaller development programs will experience a significant deviation from the mean, in either direction.鈥�
Eastern Shelf operators also stress the importance of geology.
鈥淲e had a miscalculation that what we were doing in the core Hermleigh was going to work all across Fisher County, that all we had to do is just find a thick sand,鈥� Eagle said.
鈥淲e proved that to be not totally correct鈥攖hat geology really mattered,鈥� he said, 鈥渁nd that you better do your homework to understand deposition, structure and all kinds of elements.鈥�
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Shelf moves south
Moriah still has a few locations left to drill in the Scurry-Fisher part of the Eastern Shelf. Late last year, Moriah completed a 10,500-ft lateral in Scurry County, Hannah #1H; Verado contributed some of its acreage to Moriah for the 2-mile well, Graham said.
But Moriah is hunting for the next play, too.
The company has more recently focused its drilling efforts on Tom Green and Irion counties, Texas, northwest of San Angelo.
Moriah鈥檚 first horizontal in Irion County was completed in November 2023. The Tullos Unit #1H (~8,000-ft lateral) was drilled targeting the Canyon reservoir.
RRC records show production from Tullos Unit #1H peaked at approximately 712 bbl/d in January. The well produced more than 116,000 bbl through July, according to the most recent available data.
A Strawn well completed in Tom Green County last December鈥擬ozelle Unit #1H (~10,500-ft lateral)鈥攑roduced over 600 bbl/d in April.
Harris was tight-lipped on the recent activity in the southern Eastern Shelf.
鈥淭hat play is very early on its life cycle and we鈥檙e still evaluating results to assess the return profile and attractiveness of that area,鈥� he said.
Moriah is delineating the play along with Rising Star Energy Partners LLC, which has submitted data on five wells drilled in Irion County.
Clear Fork Inc. isn鈥檛 in that part of the Eastern Shelf yet, but Eagle acknowledges that 鈥渢hey鈥檙e making really, really nice wells there.鈥�
鈥淚t鈥檚 two-tiered鈥攊t鈥檚 a Strawn and Canyon sand,鈥� he said.
Spurned or simply ignored by the publics, the Eastern Shelf remains a playground for independents.
Clear Fork, Moriah, Verado and Cholla each say the Eastern Shelf Strawn play鈥攁nd other conventional or semi-conventional 鈥渉ybrid鈥� reservoirs as Powell calls them鈥攚ill have long shelf lives going forward.
鈥淚 truly believe the independents and the small, family-owned companies are going to play the biggest role going forward on unlocking new reserves,鈥� Powell said. 鈥淓xploration of these hybrid reservoirs, I think, is in its infancy.鈥�
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