Oasis Petroleum Inc. bet the future on Big Sky country, investing millions into acquiring shale-oil acreage in northern Montana and North Dakota.

Now, the exploration and production company, backed by a high-profile local private equity firm, is hoping investors can envision potential profits and sink their capital into the Northern Plains shale plays.

Oasis has filed for an initial public offering, looking to raise as much as $350 million and secure a listing on the New York Stock Exchange under the symbol “OAS.”

Michael Lou, chief financial officer, says Oasis couldn’t comment on the March 4 regulatory filing.

Houston-based Oasis, founded in 2007, is headed by oil and gas industry veterans formerly with Burlington Resources Inc., which was acquired by ConocoPhillips in 2006.

The company is funded in large part by EnCap Investments LP. The private equity firm focuses primarily on the oil and gas sector, and also holds interests in EV Energy Partners LP, Plains All American Pipeline LP, and Marquette Exploration LLC.

Oasis attracted an initial $100 million from EnCap and private investors. By 2010, that investment had grown to $250 million.

In addition to oil, Oasis is looking to strike profitability. Financial disclosures in the regulatory filing show:

• The company posted $63 million in losses since its inception in 2007.
• Proceeds from the IPO are earmarked to repay outstanding debt ­and to fund further exploration and development. As of December 31, Oasis held $35 million in long-term debt.
• For 2010, Oasis has set aside $179 million for drilling and completing well, and the company currently holds about $41 million in cash.
• Existing principal investors and the company’s directors have yet to disclose how much of their holdings are in play in the proposed IPO.

Oasis operates in an increasingly popular hotbed for growing exploration and production firms.

The company has interests in approximately 292,000 leasehold acres in the Williston Basin of northeastern Montana and northwestern North Dakota, for a combined total investment of about $137 million.

According to a 2008 U.S. Geological Survey report, the Bakken and Three Forks formations in the region were the largest continuous oil formations in the continental United States, holding 3.65 billion barrels of recoverable oil.