In June, Australia's BHP Billiton (BHP, news) bought U.S. tight shale oil and gas producer Petrohawk. In July, China National Offshore Oil Corp. (CEO, news) (883.HK) bought Canadian oil sands producer Opti Canada. This week, Norway's Statoil (STO, news) (STL.NO in Oslo) bid to acquire U.S. oil shale producer Brigham Exploration (BEXP, news).

See a pattern here?

Global oil companies and oil-consuming countries are looking past the current soft demand for oil created by today's global economic slowdown and lower oil prices. They see a future of rising demand and higher energy prices -- and of limited opportunities for adding to reserves and production. They also see an opportunity created by today's lower oil prices and oil-producer share prices to buy reserves and exploration opportunities. And these global oil producers and oil-consuming countries are moving aggressively to seize that opportunity.

Oh, and let's not forget that money is cheap right now (if you're a global oil producer, that is). Many of these offers are all-cash deals to buy shares of the acquired companies at depressed prices.

What are you doing about seizing this opportunity for your portfolio? Let me give you a few suggestions.

Image: Jim Jubak

Jim Jubak

First, a look at Statoil

Statoil, Norway's state-controlled oil company, is an example of the larger story in microcosm. For decades, Statoil has been a leading producer of oil and natural gas from the waters of the Norwegian Continental Shelf. But, like the neighboring North Sea fields, these Norwegian fields have shown declining production as they've aged. In its most recent capital plan, Statoil announced a combination of spending on enhanced oil recovery in older fields and new exploration and production. These efforts are projected to stabilize the decline in production from the Norwegian Continental Shelf and actually lead to a slight uptick in production to 1.40 million barrels of oil equivalent in 2020 from 1.38 million barrels in 2010.

Stabilizing production in older fields is just part of Statoil's plan. It has also been spending big time to buy into areas that promise rising future production. That has included buying into joint ventures in unconventional resources in the U.S. Marcellus natural gas shale and Eagle Ford gas and liquids plays. And most recently, it has included the purchase of Brigham Exploration, a leaseholder on 375,000 acres of the Bakken and Three Fords tight oil formations in North Dakota and Montana. Current production from that area for Brigham amounts to 21,000 barrels of oil-equivalent a day. But oil industry analysts say Statoil will easily be able to increase production to 60,000 barrels a day over the next five years. Statoil has offered to buy Brigham Exploration in an all-cash offer for $36.50 a share.

That's not much higher than the recent price of a premium over the stock's recent price, but then Brigham is trading near its 52-week high of $37.87.

But what's of most interest to investors -- unless you happen to already own Brigham -- is the big jump in the price per acre that Statoil is paying for Brigham Exploration's Bakken acreage. The deal price works out to about $12,000 for each Bakken acre that Brigham has under lease. That's the most ever paid in a major Bakken deal, according to Bloomberg, and at least 50% more than Occidental Petroleum (OXY, news) and Hess (HES, news) paid for their Bakken acreage in the last year.

Record prices for oil reserves

I'm sure that seems odd to investors who have a short-term view of the financial markets and the economy. Why pay a record price for reserves and potential reserves when oil is selling for just $86 a barrel for West Texas Intermediate (the U.S. benchmark) and just $109 a barrel for Brent (the European benchmark)? We're a long way away from the heady days when oil sold for $140 a barrel. And this is before Libya gets back into production, adding more oil to global supply at a time when global demand is soft.

But oil companies aren't short-term investors, and the long-term picture looks very different. The costs of producing oil are rising -- whether you're a Statoil planning to spend more on enhanced recovery techniques or a Petrobras (PBR, news)trying to figure out how to get oil from salt formations deep under the South Atlantic. According to Bloomberg, the cost of finding and developing oil has climbed to $14.21 a barrel for Exxon Mobil (XOM, news) -- a tenfold increase in 10 years.

Those rising costs justify spending more to secure access to future reserves, especially if those reserves are in politically low-risk countries and come with relatively predictable production costs. Oil companies know what it costs to produce oil from the Bakken shales and to get it to market. Petrobras has only a guess on production costs and infrastructure needs in the South Atlantic. Exxon Mobil has only a guess on costs to produce oil and gas from the frozen Russian Arctic.