What's the prize in Basra?

What is the prize in Basra that is motivating the fight between units loyal to the Maliki government and SIIC/Badr and the Mahdi Army?  What is prompting this fight?  And what are the gains that the Maliki government believe that they can get at the end of the day if they are successful (which recent reports suggest that the Iraqi Army is 'stalled' and outgunned and out-trained by the Mahdi Army fighters they are attacking, is looking a little less likely)  The theory that the DAWA-SIIC alliance is looking to knock down the more popular and credible Sadrist currents is plausible, while the Iranian super genius manipulation theories are having issues with Mr. Occam.  But what is the net gain of this strategic approach?

Basra is valuable because it is a large population base and the only major oil export port in Iraq.  Roughly 80% of Iraqi oil exports go through Basra, so that is about 1.7 to 1.8 million barrels per day.  At world oil prices, this is roughly $166 million worth of exports per day (assume average price per barrel of $95.00) which means a massive amount of corruption, bribery, smuggling and other black/gray market money is available.  Throw in other traditional smuggling activities and this is a massive spoil.  And for the past five years, the Basra oil export systems have been maintained in fairly decent condition and has not been subject to systemic attack.

The Fadillah militia and group have the loyalty and control of the workers in the oil export sector.  However oil export infrastructrure is fragile when plentiful Semtex or C-4 is available to people who know how to use it.  The Sadrists have the working examine and the plausible premise that small motivated groups with social support can shut down oil export routes as the Sunni Arabs did that to the Kirkuk-Ceyhan pipeline for years.  So even if the Sadrists lose (which is not a sure thing at all) they can deny victory in terms of changing the allocation of spoils to advantage SIIC or Fadillah by their explosive veto, and we are seeing a possible precursor of that campaign this morning:

One of southern Iraq's two main oil export pipelines was also severely damaged in a bomb attack, officials said today.

The bombing of the pipeline, seven miles south of Basra, caused oil prices to rise yesterday to $107.70, though officials gave varying accounts of how supply would be affected.

"This morning, saboteurs blew up the pipeline transporting crude from [the] Zubair 1 [oil plant] by placing bombs beneath it," an oil company official said.

"Crude exports will be greatly affected because this is one of two main pipelines transporting crude to the southern terminals. We will lose about a third of crude exported through Basra."

Later reports suggested that up to 80% of Basra's export capacity has been shut down due to this attack. 

And given that a good chunk of the Surge's limited tactical success has been the throwing around of massive amounts of money to all armed parties who had been shooting at US forces for the past five years, the viable threat of cutting off major oil exports routes and thus severely crimping the flow of cash that is about the only claim of legitimacy that the Maliki government can beg, borrow or buy, undermines the central government which is launching this attack to undermine its rival's ability to buy votes (at much lower prices due to stronger loyalty ties).  Ahh --- negative sum prisoners dilemnas are so much fun to work with.  Maliki is screwed if his forces take the city as his government will have significantly less access to non-US government cash as the oil infrastructure will come under seige and he further solidifies the perception that he is Bush's little bitch.  Maliki is also screwed if a non-state military force defeats in a stand-up battle his army, as that tends to be a bad thing in the post-Westphalian world.