The other 60% of the change is largely a result of our revised expectation for an increase in our higher tax international jurisdiction as a percentage of 2012 pretax earnings. With this revised expectation in sales mix, we are now projecting an overall effective income tax rate for the full year 2012, excluding Libya, of between 60% and 65%. Remember, the actual effective income tax rate can vary quarter-to-quarter based on the expected annual level of sales by jurisdiction, as well as any discrete items.
On Slide 5, we've included the comparison of the total Upstream Q1 liquid hydrocarbon sales volumes, with the estimated liquid hydrocarbon sales volumes for Q2, as an aid in modeling the company's earnings with both periods excluding Libya. The timing of listings can vary based upon nominations yet to be finalized, which can affect the estimated sales volumes, as well as the percentage contributions.
As shown on Slide 6, the first quarter was a good operating quarter for the E&P segment, with higher sales volume and better prices compared to the fourth quarter. However, these increases were more than offset by higher segment income tax expense, as I just discussed, and higher DD&A and other expenses on an absolute basis because of increased activity. On a boe basis, E&P costs were essentially flat quarter-over-quarter.
Slide 7 shows that in the U.S., we increased sales volumes quarter-over-quarter reflecting our ongoing development programs, primarily in the Eagle Ford, Bakken and Woodford shale plays. Our U.S. price realizations were negatively impacted by lower domestic natural gas prices and by dislocations in the crude markets, creating wider differentials and lower crude realizations in the Bakken and across the Rocky Mountain region.After the late January and February widening in differentials, they have returned to more normal levels, narrowing substantially in March and April. On an absolute basis, DD&A and operating costs were higher in the U.S., reflecting our increased activity in the resource plays. Read the rest of this transcript for free on seekingalpha.com