HOUSTON, June 22 (Reuters) - Shares of U.S. oilfield service companies have fallen by more than 8 percent in the past month as worries about margins in the shale patch are clouding the sector's nascent recovery.
The Philadelphia SE Oil Service Index, which tracks the 15 largest publicly traded oilfield service companies, was at 153.95 on Friday, down 8.3 percent in the last month and trading near where it began the year.
Oilfield service stocks overall have lagged those of producers since the oil-price recovery gained steam last year. The recent pullback comes as some producers warned production in the largest U.S. oilfield may slow due to a lack of pipeline space to move the crude to market.
Pressure pumper C&J Energy Services last week said it would delay deployment of three hydraulic fracturing fleets, and shale producer Halcon Resources this week said it planned to drop a Permian rig next month.
"Investors are recognizing the Permian infrastructure constraint is real," said Robert Thummel, a managing director at asset management firm Tortoise. His firm recently sold its oilfield service stocks because of a lack of expected price increases in the Permian.
The Permian concerns are hitting hardest the stocks of companies that frack in the Permian. In the past month, shares of pressure pumpers ProPetro Holding Corp and Liberty Oilfield Services have fallen by 21 and 22 percent, respectively, and rival Keane Group is down about 16 percent.
Service firms with larger international operations have fared only slightly better. Schlumberger and General Electric's Baker Hughes GE are both down nearly 10 percent in the past month, while Halliburton has declined about 13 percent.
Oil production in the Permian is up 37 percent in the past year to 3.3 million barrels per day (bpd), according to U.S. government data, near the region's existing pipeline, rail and trucking capacity.
"You have these takeaway capacity issues and companies are re-negotiating their contracts saying, 'I might not need that extra frack spread,'" said Sajjad Alam, an analyst for Moody's.
Around 60 percent of the larger pressure pumpers' Permian activity is focused on customers with firm takeaway capacity or sales contracts, leaving smaller firms most exposed, analysts at Bernstein wrote on Thursday.
"The stocks have reacted already," said Colin Davies, a Bernstein analyst. "There is a risk that there is another leg down for exposed stocks as actual operations begin to react and become more visible and tangible." (Reporting by Liz Hampton Editing by Phil Berlowitz)