UPDATE 4-Halliburton shares sink as investors eye pipeline constraints

(Adds details from conference call, price action)

July 23 (Reuters) - Oilfield services provider Halliburton Co on Monday reported a sharp increase in quarterly revenue, but its shares fell by more than 6 percent as investors eyed growing pipeline constraints in the Permian Basin.

Halliburton said some of its customers are reducing activity and lowering their rig count as production in the west Texas and New Mexico outpaces takeaway capacity. The bottlenecks have pushed the price of regional crude to a steep discount to benchmark U.S. oil and are threatening to dampen demand for oilfield services and equipment.

The company's revenue rose 24 percent year-on-year to $6.15 billion in the second quarter, surpassing analysts expectations of $6.11 billion, according to Thomson Reuters I/B/E/S.

Still, investors focused on concerns that activity in the Permian will slow in the coming months.

Halliburton's shares were trading at $42.19, off roughly 6.6 percent on Monday morning.

Societe Generale analyst Edward Muztafago said Halliburton's second quarter was less about the earnings number and more about worries around transportation constraints in the Permian Basin.

Chief Executive Jeff Miller said third-quarter results would likely mirror those of the second quarter but was upbeat about the company's position in North America.

"I'm not naive to the math around the off-take issue," Miller said on an earnings conference call, adding that not all customers will respond in the same manner to the constraints. He said the bottlenecks would subside in 2019.

The company's stock price has declined about 20 percent since mid-May on concerns that pipeline constraints in the Permian Basin will slow production growth.

Halliburton, which is a leading provider of hydraulic fracturing services in North America, has benefited from soaring U.S. oil production, which reached a record 11 million barrels per day in July, according to a government estimate.

Rivals Schlumberger and GE's Baker Hughes on Friday missed quarterly revenue forecasts but delivered an upbeat outlook for the second half of the year.

Halliburton's North American revenue rose 38.4 percent to $3.83 billion, while revenue from its international business increased 6 percent to $2.31 billion.

Margins in U.S. onshore operations are closing in on what the company achieved during the previous peak in 2014, Miller said in a statement.

Excluding one-time items, the company earned 58 cents per share, in line with Wall Street estimates, according to Thomson Reuters I/B/E/S.

Net profit attributable to Halliburton rose to $511 million, or 58 cents per share, in the quarter, from $28 million, or 3 cents per share, a year earlier.

The company took a charge of $262 million in the year-ago quarter.

(Reporting by John Benny in Bengaluru; Editing by Maju Samuel and Steve Orlofsky)