There's a reason China's state-owned oil companies are rapidly becoming some of the biggest clients of Calgary's top law firms.

It's because, in some ways, the two vast countries are mirror opposites of each other. Put simply, each has what the other lacks.

Canada has the world's second-largest oil reserves, at 170 billion barrels — and the largest reserves open to foreign investment. (Saudi reserves and production are state owned, as are those of many other major exporters.) Canada also has a very small population and correspondingly smallish capital formation capacity from which to fund identified opportunities for some $200 billon worth of energy projects. And Canada is learning that it needs export alternatives to the U.S.

Conversely, China is the world's second-largest and fastest-growing oil importer and its emergence as an economic powerhouse has given it immense cash reserves with which to buy oil and gas properties, projects or entire energy companies.

China's vehicle fleet is the world's second largest, growing 20-fold in the decade ending in 2010 and now totalling 78 million units. It's also the world's largest vehicle manufacturer, producing 18.4 million units in 2011. By 2050, the Chinese fleet is predicted to surpass 500 million vehicles, easily making it the largest in the world.

Every day, China produces about four million barrels of oil and consumes about 10 million. By 2017, Chinese daily consumption is forecast to reach 12 million barrels per day, pushing imports to nine million bpd as domestic deliveries decline. And by 2050, consumption is expected to reach 20 million barrels per day, most of it coming from offshore.

Seen in this light, it's not hard to understand why Chinese state-owned oil companies are willing to spend a few billion dollars out of China's $3 trillion in depreciating foreign exchange reserves to buy oil sands assets that are likely to appreciate in value. Fees paid to Calgary law firms, running into millions of dollars, are simply inconsequential as the Chinese government seeks to maintain domestic economic growth and, thereby, it's own political legitimacy.

The same logic applies to Canadian natural gas reserves — but with two added incentives for Chinese investment. Gas is the lowest-carbon fossil fuel in an increasingly carbon-constrained world.

And North American natural gas prices, depressed by a continental glut, are running about one-tenth of the price natural gas commands in Asia.

Producing gas in Alberta and British Columbia, pipelining it to the West Coast and liquefying it for shipment to China would produce a huge and ongoing savings in energy costs on whatever reserves China might acquire.

In the process, China would help to fund development of more than $100 billion worth of proposed projects in the oilsands and a somewhat smaller number of proposed liquefied natural gas projects in Alberta and B.C. Each deal would require armies of construction workers — and smaller armies of Calgary lawyers.