(Adds details on outlook and operations in paragraph 3-5, details related to Exxon acquisition in paragraphs 7-8)

HOUSTON, Nov 2 (Reuters) - Pioneer Natural Resources on Thursday said third quarter profit fell 26% on lower oil and gas prices, but in one of its final chapters as a public company topped analysts' estimates on higher production.

Last month, the U.S. shale producer agreed to be acquired by oil major Exxon Mobil in an all-stock deal valued at . The deal closes next year and the report is likely one of Pioneer's last as a public company.

Pioneer increased its full-year production forecast to between 708,000 and 713,000 barrel of oil and gas per day (boepd), the second hike this year.

It also cut its projected 2023 drilling and completions spending for a second time, to $4.38 billion from $4.48 billion, 3.8% lower at its midpoint from its original estimate.

Pioneer has attributed its higher output to longer lateral wells, while it has saved on costs by simultaneously fracking multiple wells and using local mines for frack sand.

During the quarter, Pioneer's average price for oil, gas and natural gas liquids fell 25% to $52.13 per barrel of oil equivalent. Daily sales volumes rose 10% to 721,479 barrels of oil and gas.

The company has discontinued providing quarterly outlooks and does not plan to hold a call with investors to discuss results due to the pending merger with Exxon, officials said.

Exxon is buying Pioneer to boost its oil production. The No. 1 U.S. oil company last week posted a

sharply lower

$9.1 billion third-quarter profit, missing analysts' estimates for the second quarter in a row, with profits off 54% from a year ago.

Pioneer's net income, excluding items, fell to $1.4 billion, or $5.83 per share, in the three months to Sept. 30, from $1.9 billion, or $7.48 per share, a year earlier. Analysts had estimated a profit of $5.55 per share.

(Reporting by Arathy Somasekhar in Houston Editing by Chris Reese and David Gregorio)