The wait for take-away capacity in the Utica play, which produces from Ohio’s Point Pleasant formation, has been surprisingly fortuitous. Word on the E&P street is that producers there may take an entirely new tack in their post-completion procedure.
Normally, after fracture stimulation, frac fluids are flowed back for several days while the well is tested for hydrocarbon output. The well may then be put into sales immediately or, if take-away infrastructure isn’t ready, it is shut in for a while.
Now, various producers are talking about flowing back for only a few hours for a brief test and then shutting a well in for 30 or more days—or, shutting it in immediately upon completion. Word is that the initial potential (IP) doubles or triples.
Chesapeake Energy Corp.’s Buell 10-11-5 8H well in Harrison County, Ohio, is what first piqued producers’ and completion engineers’ interest in this idea of higher IPs after not flowing back immediately after stimulation. The well, which was shut in for some 100 days after completion, later had a peak rate of 3,010 barrels of oil equivalent (BOE) per day of wet gas. This past May—nearly a year later—it was making 1,040 BOE a day. Chesapeake expects it to make 575,000 barrels of liquids and 13 billion cubic feet of gas.
Chairman and chief executive officer Aubrey McClendon said in an earnings call in May, “It may well be our best shale well ever.” And, Chesapeake has drilled thousands of shale wells.
John Walker, executive chairman of EV Energy Partners LP, which is a partner with Chesapeake in Ohio, told Bentek Energy symposium attendees in May that predictable results from shutting in wells before flowback remain unknown, but it is finding improved IPs in the Utica from doing so. “There are no models. It’s just pure experimentation right now,” he said.
A possible explanation may be that the Point Pleasant formation has low water saturation of between 3% and 15% and very high capillary pressure, one engineer says. If the well is shut in for an extended period, he explains, “the water either gets ‘sucked’ into the reservoir, so it no longer has a high ‘frac face’ water saturation, and/or it is absorbed by the clays.”
Pennsylvania-based Rex Energy Corp. notes in its June investor presentation that results from Utica and Marcellus wells that are shut in after stimulation are interesting. “When water saturations are less than a typical 35% to 40%, a shale is said to be desiccated and frac water will try to flow from the wellbore into the rock.”
In the Marcellus in western Pennsylvania, water saturation is 10%; in the Utica in Pennsylvania and Ohio, saturation is 5% to 15%, Rex reports. “In fractures, capillary effects of water flowing into desiccated shale are stronger than flowing gas pressures, and a blockage hinders gas flow. Shutting a well in stops flowing gas pressure and allows water to absorb into rock and get out of the way of gas flow.”
In short, the frac fluid pushes deeper into the formation under pressure, displacing the hydrocarbons toward the wellbore.
Jim Palm, Gulfport Energy Corp. chief executive, calls the Point Pleasant formation “thirsty rock.” He has already decided to shut in the company’s future Utica wells immediately upon completion, he told OGIS New York attendees in April. “We think that’s the way to go….” The company’s first test of this is with its Wagner 1-28H. Completed with a 28-stage frac in Point Pleasant this spring, it was in a 60-day “resting period” in early June.
Ron Gajdica, EV Energy Partners senior vice president, said in the company’s earnings call in May, “There’s a wide range of opinions about the mechanisms that are driving this dissipation process. Nobody really knows for sure…The reservoir models are not coded to allow modeling of this phenomenon. So it’s really anyone’s guess at this point in time. It’s very early in understanding….”
McClendon said of Chesapeake’s future Utica wells, “We’re not bringing them on immediately after completion. Sometimes that’s due to pipeline delay but, sometimes, it’s due to certain engineering and production-performance benefits that we get by leaving them shut in for a while.”
One industry member tells Investor, “This very much may change how unconventional resources are produced in the future.”
Some commentary is from transcripts of producers’ earnings calls at SeekingAlpha.com
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