HOUSTON, May 26 (Reuters) - Chevron Corp will consolidate its exploration and production and refining units under a single executive, it said on Thursday, as the company sharpens its focus on U.S. oil and gas production and cost efficiency.

Chevron's decision to raise its U.S. output has been reinforced by global sanctions against Russian oil, following the Ukraine invasion in February. The consolidation comes after a streamlining two years ago that would cut about 10% of its workforce.

The second largest U.S. oil producer has pledged to add 15% this year to its output in the top U.S. shale basin, which supplies about 23% of its global production.

The combined upstream, midstream and downstream business segments will report to a new executive vice president, Nigel Hearne, effective Oct. 1.

Hearne will run the Oil, Products & Gas business, Chevron said. He previously was president of its Europe, Asia and Pacific production.

The company is also consolidating upstream operations into two regions – Americas Exploration & Production and International Exploration & Production. Americas will be run by Bruce Niemeyer and International by Clay Neff, it said.

Jobs affected are mainly at the senior executive level, a spokesperson said.

The reorganization will "bring strategy, policy and business development into tighter alignment as we focus on leveraging our strengths to deliver lower carbon energy to a growing world," Chief Executive Michael Wirth said in a statement.

Chevron's U.S. oil and gas production rose 10% in the first quarter over a year earlier, while international output fell 8%. The company pumped 3.06 million barrels of oil and gas per day (boepd) in the first quarter.

Production in the Permian, the largest U.S. shale basin, grew to a record 692,000 boepd. It recently lifted its full-year Permian guidance by 15% over 2021 to between 700,000 and 750,000 boepd.

Wirth recently said Chevron was looking for U.S. acquisitions to enhance its natural gas and liquid natural gas (LNG) operations.

(Reporting by Sabrina Valle in Houston, additional reporting by Rithika Krishna in Bengaluru; Editing by Krishna Chandra Eluri and Richard Chang)