* Plant downtime, facility upgrades hurts Colorado basin output
* Facility constraints could hurt other producers - analysts
* Company's 2nd-qtr output misses expectations
* Production forecast for rest of year below expectations
* Shares fall as much as 6 pct to 2-month low (Adds executive, analyst comments, details on U.S. operations)
By Swetha Gopinath
July 24 (Reuters) - Noble Energy Inc warned that a lack of infrastructure in its main oilfield in the United States would hurt production, indicative of how the growth of processing and pipeline facilities in U.S. shale fields is lagging rising output.
Noble's shares fell as much as 6 percent to a two-month low after the company's production forecast for the rest of the year fell short of analysts' expectations.
Production from the company's operations in Colorado's Denver-Julesburg basin rose in the second quarter, but missed its own expectations, hurt in part by downtime at a third-party processing plant and facility upgrades at over 60 wells.
"There's such a mad rush to build out U.S. shale plays in every respect, not just production, but also in logistics transportation," said S&P Capital IQ analyst Stewart Glickman.
"Production had to slow down a bit because there just wasn't enough takeaway capacity."
Noble gets a third of its total production from the Denver-Julesburg basin, and analysts said the infrastructure problems there could also hurt Bonanza Creek Energy Inc , Bill Barrett Corp and PDC Energy Inc.
Noble's shares were down 3 percent at $71.95 in afternoon trading. Shares of Bonanza Creek, Bill Barrett and PDC Energy were mostly unchanged.
Noble, which also operates in deepwater Gulf of Mexico and offshore West Africa, said total oil and gas production rose 14 percent to average 290,000 barrels of oil equivalent per day (boe/d) in the second quarter ended June 30.
That fell short of the company's own forecast and also missed analysts' estimates.
Noble expects to produce as much as 305,0000 boe/d in the third quarter, well below the 324,000 estimated by Simmons & Co analysts.
The company said fourth-quarter production could touch 330,000 boe/d, slightly above Simmons & Co's 328,000 forecast.
Noble, which also operates in a giant natural gas field off Israel's coast, said it expects its third-quarter natural gas sales in the country to be hurt by the ongoing conflict there.
The company and its partners in the Leviathan gas project in the region suffered a setback after Australia's Woodside Petroleum Ltd pulled out in May, leaving them without the expertise to kickstart exports sooner.
Texas-based Noble said on Thursday that it signed on two regional customers for natural gas from the Leviathan and Tamar projects in Israel.
"We are closing in on securing additional customers that will further support the first phase of development at Leviathan", Chief Executive Charles Davidson said.
Noble's net income nearly halved to $192 million, or 52 cents per share, in the second quarter due to a $187 million loss on commodity derivatives.
However, its adjusted profit of 87 cents per share beat the average analyst estimate of 79 cents, according to Thomson Reuters I/B/E/S.
(Editing by Maju Samuel and Savio D'Souza)