That's precisely what it says, but just because an executive order says that does not establish that "it is necessary to prevent a bunch of lawsuits" to get Iraq's oil economy back on its feet as a fact. One would hope that a politician (or his legal advisors) would be smart enough to craft an executive order in such a way that it sounds good (that's called rhetoric, usually politicians and lawyers are good at that). However, sounding good and actually delivering on that are two different things.

The preponderance of evidence seems to suggest that this executive order does not really have the intent which you describe; despite it being ordered (as far back as 2003 no less) Iraq's oil industry has gone nowhere, also recall that billions of dollars from the Iraqi Development Fund simply dissapeared when Paul Bremer was in charge, not to mention the numerous cases where Halliburton was found to be charging for goods and services it never provided.

When you look at the entirety of the situation this seems far more evident of a bunch of corrupt bureaucrats and corporate cronies trying to get away with murder.

You could possibly argue for such an executive order only if it said instead that legal cases would be pending until such time as Iraq's oil infrastructure was repaired. But an order that grants them immunity for anything related to rebuilding Iraq's infrastructure for all time? That definitely indicates that they intend to break the law.

Furthermore, even if what you said is true I don't see how you could possibly claim that it wouldn't be good for the big oil companies. If Iraq's oil infrastructure were rebuilt quickly and we didn't have to pay that would be good for American taxpayers, but it would also be good for big oil companies because they're the ones who get to sell the oil and make a profit from it (profitability sooner).

Read the executive order. It basically says that in order to get the Iraqi oil production back quickly to help finance the reconstruction of Iraq it is necessary to prevent a bunch of lawsuits from tying up the process in court for years. Without such an order it is likely that there would be no revenues from Iraqi oil and the entire cost of the Iraq reconstruction would fall to you know who--the American taxpayer. Sounds like it's good for the average American not the big oil companies.