Washington — US producers may be growing increasingly skeptical of the US Energy Information Administration's estimates of drilled but uncompleted wells in shale plays, an indication that domestic output may not be able to respond to a price spike or supply disruption as rapidly as forecasts may indicate.

In its latest quarterly energy survey, the Federal Reserve of Dallas said roughly half of the oil and gas executives polled claimed EIA's was overestimating the number of drilled but uncompleted wells, or DUCs, in the Permian Basin. Roughly a quarter of those executives said EIA's Permian DUCs estimates were significantly higher than their own.

"My sense is the EIA DUC number implies more production capacity than actually exists and leads to downward revisions of supply estimates, which we have seen in the last six months," one executive from an exploration and production company wrote.

"The EIA has no clue on their estimated number of DUCs, in my opinion," wrote another, claiming that a loose definition of DUC is causing EIA to count smaller "spudder" wells and overestimate DUCs by thousands.

The survey, conducted earlier this month and released Wednesday, polled 164 energy companies, including 108 exploration and production firms, and 55 oilfield services firms.

"Not surprisingly, the majority of survey respondents believe the EIA is overestimating the number of DUCs," Sasha Sanwai, an analyst with UBS, wrote in a report Wednesday. "Common pushbacks including the lag with reporting completions/underreporting and inclusion of spudder wells/legacy wells unlikely to be completed."

ONGOING DOUBTS

These criticisms are not new.

In March, analysts with Raymond James & Associates claimed EIA was overestimating the number of DUCs in the seven biggest US unconventional plays. EIA was including thousands of wells which were drilled years ago, but are unlikely to ever be completed in their estimates, Raymond James analysts said. EIA's DUCs estimate may be overstated by as much as 2,000 wells, or about 30%, they said.

In July, Kayrros, an analytics firm, claimed the backlog of DUC wells is "considerably smaller than thought," claiming the DUC inventory in the Permian was about 1,000 wells in any given month. By comparison, EIA in July estimated that there were about 4,000 DUC wells in the Permian the previous month.

"We are looking at it closely," said Jozef Lieskovsky, an EIA analyst, said in an interview Friday with S&P Global Platts, of the criticism. "We always felt that if we made [these estimates] public, then we were going to hear from who's opposed to it."

Lieskovsky pointed out that much of the criticism of EIA's DUCs estimates was coming from E&P companies, not the oilfield services companies he said may be more attune to the issue.

He said much of the debate over DUCs is just when a DUC needs to be counted out of the inventory. He pointed out EIA grants a relatively long shelf life to DUC, claiming certain wells can be completed and begin producing after three years of remaining in uncompleted status.

Lieskovsky said the EIA began estimating DUC wells as part of its monthly Drilling Productivity Report following the 2014 oil price collapse. He said the EIA had little data on how much shale operators may be able to produce without drilling new wells.

"A high inventory of DUCs may affect the size and timing of the domestic supply response to a persistent or significant rise in oil prices with or without significant changes in the number of active drilling rigs," EIA said in a note on its DUCs estimates last week.

DATA CRUNCH

The effort of estimating DUCs has been complicated by producers who have stopped publicly disclosing their data on DUCs, largely in order to avoid criticism over spending capital on uncompleted inventory, Lieskovsky said.

"They will tell you their active rig count." Lieskovsky said. "They will tell you how many wells they've drilled and some, but not all; will tell you how many wells they've completed. So, we go and we kind of benchmark how big is the producer, and then we look how many wells they drilled with the rigs they had and we try to estimate the wells-to-rig ratio."

Last week, EIA estimated there were 7,950 DUCs in the top seven US shale plays in August, down 142 from July, but up 769 in a year. The inventory of DUCs in the Permian climbed to 3,839 in August, up from 2,760 a year earlier, according to EIA's estimate.

EIA's DUCs estimate is roughly twice as high as that of S&P Global Platts Analytics, due to differences in methodology. For example, EIA counts all wells 20 days after drilling commences as a DUC, while Platts Analytics uses the natural cycle by basin, which is typically 20 to 90 days after a well is drilled.

In addition, EIA uses older wells unlikely to ever be completed in their counts and uses FracFocus as a source of completion information, which can have significant lag times and may overestimate counts.

-- Brian Scheid, brian.scheid@spglobal.com

-- Starr Spencer, starr.spencer@spglobal.com

-- Edited by Jim Levesque, newsdesk@spglobal.com