Under terms of the deal, Spartan shareholders would receive 0.1169 of a Bonterra share for each of their shares, giving them 35 per cent of the combined company.
Bonterra has also committed, subject to the completion of the arrangement, to increase its monthly dividend to 28 cents from 26 cents beginning March 2013.
Based on Bonterra's 30-day closing price of $43.05, the "implied price" is $5.03 per for each of Spartan's almost 83.4 million shares.
On the Toronto Stock Exchange, Bonterra shares were up 21 cents at $42.31 near midday, while Spartan stock was down three cents at $4.85 although still up from Friday's close of $4.40.
Meanwhile, Spartan has agreed to terminate its Nov. 20 agreement with Pinecrest Energy Inc. (TSXV:PRY) and pay it a $12.5-million non-completion fee after determining that the Bonterra deal constituted a "superior proposal."
The transaction, expected to be completed in late January, requires the approval of two thirds of shareholders of both companies as well as regulatory and court approvals.
Management and directors of Spartan holding approximately 23.1 per cent of outstanding shares have entered into support agreements.
The Bonterra arrangement also provides for a reciprocal non-completion fee of $12.5 million under certain circumstances.
Bonterra says the merged assets will provide "strong strategic value for both groups" of shareholders as the resulting company will have "one of the premier light-oil assets concentrated in the Pembina region, which will be comprised of a complimentary production base and a long-term inventory of drilling opportunities that is anticipated to drive future growth."