PetroChina is quite the tease. Wrapping up its first-quarter results, slipped out close to midnight on Monday, Asia's biggest crude producer signalled its determination to “seize historic opportunities” during “this important and strategic period”. Chairman Jiang Jiemin first sent shivers down spines last October, when he mused it was a good time to buy companies cheapened by the great de-leveraging.

It can't hurt to keep overseas rivals guessing. With a lightly geared balance sheet and a maturing, relatively high-cost portfolio, state-owned PetroChina has both the means and the appetite to go hunting. But the reality is that locking in long-term oil supplies at favourable prices probably won't be done the old-fashioned way, launching knockout bids for public companies. China tried that four years ago, when Cnooc trampled all over the Unocal/Chevron merger and got nowhere.

Consider its adventures in central Asia. The company gained a foothold in 2005 with the $4bn acquisition of PetroKazakhstan, through its parent CNPC, when the host nation was desperate for cash and expertise. Amid heightened resource nationalism, progress has since been more circumspect. Earlier this month, PetroChina added to its portfolio half of MMG, Kazakhstan's fourth-largest energy company. But in return for the right to invest, Chinese policy banks agreed to lend the country $10bn. It's been a similar story in Brazil and Venezuela, where China has doled out loans in exchange for oil and influence. In Russia, long-running negotiations bore fruit in February, when China Development Bank extended $25bn to distributors Rosneft and Transneft, collateralised by guaranteed oil deliveries equivalent to 8 per cent of current imports.