A company like Shell with all its wealth and power is capable of...

A company like Shell with all its wealth and power is capable of gaining access to the most prolific hydrocarbon basin. Smaller companies cannot afford the sums of money these giants need to put up front to operate in these areas. In Shells case classic example is the Barents Sea. Shell are gaining increased access to the acreage by applying for licences through Norway and partnering Gazprom. This is an area said to hold some of the worlds largest gas reserves, estimated at approximatley 380 trillion cubic feet. The costs are enormous, but the likelihood of multiple commercial strikes increases.

All these Super majors run around the world drilling in potential oil and gas fields. Hit pay, evaluate the area and move on if the find is not a substantial one. Classic example of Shell doing this is in Tunisia. Shell drilled 2 wells in both the Dougga prospect and the Tazerka prospect. They found net pay in the Albiol and Birsa sandstone.Shell proceeded to walk away, plugging and abandoning the successful wells for more lucrative acreage. Tazerka is currently a producing prospect in Tunisia and Dougga is now on it way to being re-drilled.

This is just how they operate, oil and gas is a competitive industry. They seek minimal risk for maximum reward and they have the cash to splash to achieve it.
Recently an accused Libyan terrorist has been released by the Scots and sent back to Libya under the influence of the British. They believe this move has now potentially opened the doors for the European majors, primarily Shell and BP, to step in gain access to the 44 billion barrels of oil said to lie below the desert. Big money = Big oil and gas at relativley low risk, thanks to the abundance of the stuff where super majors operate.