Oct 4 (Reuters) - Exxon Mobil Corp on Tuesday signaled strong third quarter operating profits on the heels of the second quarter's all time high as earnings from high natural gas offset weaker refining and chemicals, according to a securities filing.

The largest U.S. oil producer issued a snapshot of factors affecting third quarter results that showed operating results could land near its $17.9 billion second quarter results.

The preview indicated natural gas was the one business to benefit from higher prices.

Exxon and rivals this year have posted sky-high earnings on rising energy prices and demand aided by cost-cutting.

In the third quarter, U.S. natural gas prices averaged $8.47 per million British thermal units, up from $7.17 mmBtu in the second quarter. Brent prices eased to $98 per barrel in the same period, from an average of $109 between April and June. Exxon's official results are due on Oct. 28. (Reporting by Arunima Kumar in Bengaluru; Editing by Sriraj Kalluvila)