Enterprise’s NGL fractionation business reported a $15 million, or 27 percent, increase in gross operating margin to $69 million for the third quarter of 2012 from $54 million reported for the same quarter of 2011. Our Mont Belvieu fractionators reported an $18 million increase in gross operating margin, which was primarily due to higher volumes and revenues associated with our fifth NGL fractionator that went into service in October 2011. Enterprise’s South Texas and Promix fractionators also reported increases in gross operating margin. These increases were partially offset by the Norco and Baton Rouge facilities, which reported an aggregate $6 million decrease in gross operating margin. The lower volumes fractionated at Norco and Baton Rouge were attributable to more NGLs being fractionated in Mont Belvieu and downtime associated with certain third party-owned production facilities in the Gulf of Mexico and storage facilities in Louisiana due in part to the effects of Hurricane Isaac. Fractionation volumes for the third quarter of 2012 increased 18 percent to 653 MBPD compared to 554 MBPD in the third quarter of 2011.
Onshore Natural Gas Pipelines & Services – Enterprise’s Onshore Natural Gas Pipelines & Services segment reported a $28 million, or 18 percent, increase in gross operating margin for the third quarter of 2012 to $184 million from $156 million for the third quarter of 2011. Total onshore natural gas pipeline volumes increased 1.8 TBtud, or 15 percent, to a record 14.2 TBtud for the third quarter of 2012.
The Acadian Gas system reported a $46 million increase in gross operating margin and a 1.5 TBtud increase in natural gas pipeline volumes compared to the third quarter of last year as a result of its Haynesville Extension pipeline, which began commercial operations in November 2011. Gross operating margin from the Texas Intrastate system increased $16 million from the third quarter of 2011 on an 8 percent increase in pipeline volumes that was primarily attributable to growing production from the Eagle Ford Shale. This increase was partially offset by the San Juan gathering system which reported a $10 million decrease in gross operating margin for the third quarter of 2012 compared to the third quarter of 2011 primarily due to lower revenues, including certain gathering fees that are indexed to natural gas prices, and a 69 billion British thermal units per day (“BBtud”) decrease in volume. Gross operating margin also decreased by $9 million associated with our Mississippi natural gas storage and Alabama pipeline assets that were sold in December 2011 and August 2011, respectively. Gross operating margin from natural gas marketing activities for the third quarter of 2012 decreased $6 million compared to the same quarter of 2011 due to lower sales margins.