North Dakota's Bakken Shale and lesser-discussed Three Forks formation are on pace to become one of the 10 top oil fields in the entire world. That'll happen once the region's oil production tops 1 million barrels per day, which should happen any month now. The world-class play has attracted global oil giants like Norway's Statoil (EQNR 0.17%), as well as numerous entrepreneurs, all of which are hoping to strike it rich.

A lot of the easy money is gone as the Bakken has fueled tremendous gains for a whole host of oil and gas companies. However, there's still money to be made from the play -- only 10,000 of the projected 50,000 total wells have been drilled so far. The industry believes it is still in the early stages of a 20-year development program. That leaves a lot of room to grow for some of the play's names that are still flying under the radar of investors.

Three-pronged approach
Triangle Petroleum (NYSEMKT: TPLM) is a name few investors know. There's good reason for that, as its market cap is slightly more than $700 million. But, as its name hints, the company owns three different Bakken-based energy businesses, giving it three angles to pursue growth in the play.

Triangle's first Bakken business is its wholly owned exploration and production business, Tusa. To date, Tusa has amassed a 94,000-net-acre position in the play, which is pumping out about 7,400 barrels of oil equivalent per day, or BOE/d. In addition, Triangle Petroleum wholly owns an energy service subsidiary called RockPile Energy Services that is focused on hydraulic pressure pumping and well completion. Along with keeping Tusa's costs down, 53% of RockPile's completion jobs since being formed have been for third parties. Finally, Triangle Petroleum owns a stake in a midstream gather and processing company called Caliber Midstream that's starting to place assets into service.

Add it all up, and Triangle Petroleum is building a pretty compelling company for investors looking for a multipronged approach to investing in the Bakken Shale oil boom.

The Bakken ETF
Another company that is taking a unique and diversified approach to the Bakken Shale oil boom is Northern Oil & Gas (NOG 1.01%). The company owns a small, nonoperated stake in more than 1,700 producing wells in the Williston Basin. Furthermore, by staying one step ahead of the drill bit, Northern Oil & Gas has acquired a long runway of future growth as drilling continues.

The other important consideration is that an investment in Northern Oil & Gas is one in the wells of a number of top Bakken Shale producers. For example, of the 1,700 wells that Northern has participated in, 3.9% are operated by Statoil. It even has participated in about 2% of the wells drilled by Triangle Petroleum. Overall, the company has more than 25 different operating partners, which has reduced its risk.

Basically, taking a stake in Northern Oil & Gas is akin to investing in a Bakken ETF that's directly invested in the wells. It's a unique approach. Given the vast growth that lies ahead, Northern Oil & Gas should continue to grow for many more years.

Massive potential
Oasis Petroleum (OAS) doesn't get enough credit for the massive position it has built in the Bakken Shale region. The company has amassed nearly half a million net acres in the play after it grew its position by almost 50% last year. At its current drilling rate the company can drill on that land for more than 16 years. To put its size into perspective, Statoil's position in the play is just 330,000 net acres.

In addition to its vast land position, Oasis has joined Triangle Petroleum with its own three-pronged approach to the Bakken Shale. The company's vertical moves include its own oil-field service business, as well as some midstream assets. These investments are really helping Oasis to keep costs down; the company expects to drill its wells for about $7.3 million apiece this year, well under the $10.5 million it cost the company in 2012.

This is a company with a massive land position and a low-cost drilling operation. Over time that should create a lot of value for investors.

Investor takeaway
The Bakken oil boom still appears to be in the early innings. While the easy money is gone, investors can still find an under-the-radar name with the potential for long-term gains.