UPDATE 4-Precision bets on natural gas with Grey Wolf bid

(Adds analyst, CEO comments. Changes dateline from NEW YORK)

By Jeffrey Jones

CALGARY, Alberta, Aug 25 (Reuters) - Precision Drilling Trust (PD_u.TO), Canada's biggest oil and gas rig operator, will buy U.S.-based Grey Wolf Inc GW.A in a $2 billion deal aimed at locking up business in hot unconventional prospects from southern Texas to northeastern British Columbia.

The value of the friendly cash-and-stock offer is less than an offer Precision made for Grey Wolf in June, but natural gas prices have fallen more than 40 percent since then.

Precision, which operates about a quarter of Canada's land rigs, has been stalking Grey Wolf as a way to accelerate its U.S. expansion without flooding the market with new rigs.

The deal's success will ride on a recovery in gas prices, which will drive oil companies to boost spending on plays like Louisiana's Haynesville shale and British Columbia's Horn River shale, Pritchard Capital Partners analyst Mark Brown said.

"The stocks of these companies are highly dependent on natural gas prices and shareholder acceptance of this deal will be predicated on what the valuations look like depending on how that changes," Brown said. "It's going to be a huge driver."

Precision units sank nearly 5 percent to C$21.17 on the Toronto Stock Exchange. Grey Wolf shares were off 8 cents at $8.51 on the American Stock Exchange.

New York Mercantile Exchange gas was selling for $7.65 per million British thermal units on Monday, down from $13.35 at the end of June, when Grey Wolf spurned an unsolicited $10-per-share offer from Precision in hopes of proceeding with its own takeover of Basic Energy Services Inc (BAS.N).