Last month, we saw both Williams (NYSE: WMB) and Hess (NYSE: HES) snap up prime oil acreage in the North Dakota Bakken play for roughly $1 billion each. Now Occidental Petroleum (NYSE: OXY) is joining the party, with a $1.4 billion purchase of its own.

With 180,000 contiguous net acres covered under the deal, Oxy is paying around $7,800 per acre. That places the purchase price squarely in the mid-range of recent deals.

As an aside, all of these transactions show how deeply conservative GeoResources (Nasdaq: GEOI) was being with its $2,000 per acre net asset value estimate for unproved Bakken land. The shares of that smaller player have leapt 40% since I looked at the company back in mid-September. Oops. But let's get back to Oxy.

Investors might not readily associate the California heavyweight with domestic shale plays. The firm makes more headlines with its operations in places like Iraq and suddenly hot Colombia, but Oxy has quietly gone about building a very significant unconventional oil and gas business here in the States. I know this because the company made this stunning disclosure in a May 2010 press release: "Oxy now derives over one-fourth of its California production from shales."

This company is the largest gas producer, and second-largest oil producer (after Chevron (NYSE: CVX)), in California. That means we're looking at a very significant shale player.

So what does this bit of background tell us about Oxy's entry into the Bakken? You can interpret Oxy's stepping out into a more crowded shale play as a sign that the company is very confident in the technical knowledge it has developed in its California plays, and sees the potential to produce very strong returns on invested capital. 

A cynic might take the move to suggest that the California plays aren't all that and a bag of chips, hence the desire to push out into other regions. Given Oxy's tremendous track record of shareholder value creation -- according to Bloomberg, the shares have beaten the S&P 500 for 11 years in a row -- as well as its formidable technical prowess, I think the less cynical interpretation is much more appropriate.

Don't be surprised to see Oxy become a big name in the Bakken over the next few years.

See what other firms are looking to cash in on a California shale rush.