Under the agreement, Beaumont shareholders can receive $5.62 in cash or 0.40 of a Whitecap common share for each Beaumont share they hold.
The cash available under the deal is capped at $103.4 million.
Whitecap will also assume about $70.5 million in Beaumont debt.
Beaumont has operations primarily in the Kerrobert area of west-central Saskatchewan, located nearby Whitecap's existing operations.
Whitecap said the deal will be partially funded with a $110-million bought deal equity financing.
The company has signed a deal with a syndicate of underwriters to issue 8.149 million subscription receipts at a price of $13.50 each.
Shares in Whitecap, which announced the deal after the close of markets, were up 57 cents at $13.93 on the Toronto Stock Exchange on Wednesday.