The number of rigs targeting oil in the U.S. climbed during the first full week of May as energy producers used a record number to drill in Texas’s Permian Basin, the nation’s biggest onshore crude play, Bloomberg news said May 9.

Oil rigs rose by one to 1,528, data posted on Baker Hughes Inc.’s (NYSE: BHI) website showed. The gas count was unchanged at 323, the

Houston-based field services company said. Those targeting crude in the Permian gained two to 539, the highest count in data going back to February 2011.

Energy producers are using horizontal drilling and hydraulic fracturing to draw record volumes of oil and gas out of U.S. shale formations from North Dakota to Texas. The boom in drilling has helped boost the nation’s total rig count by 98 this year.

Apache Corp.’s (NYSE: APA) North American onshore liquids production rose to a record in the first- quarter, boosted by a surge in output from the Permian, the Houston-based company said in a conference call with analysts May 8.

“The beauty of our whole portfolio in the Permian is we’re having great results not just in the Wolfcamp, and so we’re excited about the whole thing,” John J. Christmann, Apache’s COO of North America, said on the call.

In the Bakken shale play of North Dakota, Continental Resources Inc. (NYSE: CLR), its biggest leaseholder, said it’s “ready to shift into high gear.” The company’s rig count in the Antelope area alone will add two by the end of the year, Harold Hamm, the company’s CEO, said during a conference call with analysts May 8.

West Texas Intermediate crude for June delivery fell 27 cents to settle at $99.99 a barrel May 9 on the New York Mercantile Exchange, up 3.7% in the past year.

U.S. oil production slipped 2,000 barrels a day in the seven days ended May 2 to 8.35 million after reaching the highest level since 1988 last month, data compiled by the Energy Information Administration (EIA), , show. Oil supplies fell 1.78 million barrels to 397.6 million, according to the EIA.

U.S. gas stockpiles rose 74 billion cubic feet last week to 1.055 trillion, EIA data show. Supplies were 48.2% below the five-year average and 43% under year-earlier inventories.

Natural gas for June delivery fell 4.1 cents to close at $4.531 per million British thermal units on the Nymex and has risen 14% in the past year.

“Projections for natural gas storage are far below the level to meet the five-year average at the end of October,” James Williams, president of energy consulting firm WTRG Economics in London, Ark., said by telephone. “Gas prices will probably rise later in the season and the rig count with it.”

Rigs on land dropped by four during the week to 1,782. Rigs in inland waters were unchanged at 14. The offshore rig count, primarily in the Gulf of Mexico, rose by five to 59.

Miscellaneous rigs, which usually drill for geothermal energy, were unchanged at four.

Energy rigs in Canada slid by 18 to 145, following a seasonal drilling pattern.