Wolfcamp learning

Collaboration Play

American Association of Petroleum Geologists (AAPG)

There may be no “I” in team, but there certainly is an “E.”

In the oil arena, it can stand for Exploration or Engineering. Or both.

In a specific area of west Texas, it also can stand for Eagle Oil & Gas Co.

Bill Fairhurst
Bill Fairhurst

Teamwork – with all three “E”s – is what made Eagle a premier operator in the area, says AAPG member Bill Fairhurst, vice president of exploration and land for the independent company.

It wasn’t an easy project to tackle – when Eagle went into west Texas, deep in the heart of the southern Delaware Basin, oil shale plays were a relatively new development.

“It’s hard to realize now, that we hardly knew anything about them – there’s such an emphasis on them today,” Fairhurst said.

The company, however, had some horizontal successes in the Barnett Shale, and it was building on that when their geologists began looking for the next play.

They followed it into the Delaware and the Wolfcamp shale in Reeves and Ward counties.

Early wells in the area were successful – but not terribly so.

Borrowed Expertise

In 2009-10, when many companies in the region were going sideways, Eagle went straight ahead – or, to be precise, straight down.

The company focused first on sandstones above and below the Wolfcamp shale, “which were very attractive to geologists,” Fairhurst said.

Drilling produced “shows and flares all the way,” he recalled. “The logs look like it’s all pay – (and) after completion, the production logs were very valuable to see what’s going on.

“We’re producing tremendous volumes of water, and minor hydrocarbons from the sandstone,” he said. “Most of the oil was from shale and the higher Third Bone sandstones.

“We made some trades with other companies and focused in on Reeves County, on the heart of the play, with vertical wells,” he continued.

“We brought technology we had learned in a Haynesville Bossier play to the Wolfcampian shale,” he said. “We shortened out the intervals in the shales between the fracing stages ... and pumped at higher rates and volumes to frac the shale like the Haynesville Bossier.”

While early wells came in at 300-500 barrels per day, production usually dropped off quickly. But, Fairhurst said, looking at a moving average of wells from first to the 30th, “the trend of production is going up.”

“We are applying what we’re learning as we go, and that slope of increased production per well today is the same as it was two years ago,” he said. “We’re still learning and still having just as much impact on the economics.”

A Team Win

Fairhurst explained that this all occurred over three years, and that “it was a much more collaborative effort between geology and engineering (than traditional plays).

“We revised our exploration models continually ... working with the engineers on a daily basis,” he said. “That’s what’s been a lot of fun – this is primarily two or three geologists and two or three engineers meeting to share their insights and discuss their interpretations.

“Together, they have moved this project forward,” he said.

Fairhurst and AAPG member Mary Lisbeth Hanson Wallace – granddaughter of past AAPG president and legendary oilman Bruno Hanson – presented a poster at the AAPG Annual Convention and Exhibition, and, along with AAPG members Frank Reid and Nick Pieracacos, presented a full paper on the play’s evolution at the recent Southwest Section annual meeting in Fort Worth. All are Eagle geologists.

The title was “WolfBone Play Evolution, Southern Delaware Basin: Geologic Concept Modifications That Have Enhanced Economic Success.”

According to their presentations, the unconventional Wolfcamp shale is a heterogenetic resource including quartz, carbonate and kerogen. The “sweet spot” appears to be the proximal basin floor, where quartz and kerogen accumulated, with episodic deposition of carbonate debris flows from the shelf.

During maturation large volumes of oil were sealed in place (108 MMBOIP per section). Expansion from kerogen to oil in a sealed system resulted in overpressure and abundant fracturing that has resulted in enhanced productivity.

“Our fracs were in nearly vertical natural fractures, nearly 85 degrees ... the number of fracs we penetrated was just phenomenal,” Fairhurst said.

“With fracs 85 feet apart and natural fractures at 85 degrees,” he added, “that previously frac-stimulated fracture set is only a couple of inches from the wellbore.”

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