Severe weather conditions early this month caused a double whammy for the two interstate natural gas pipelines serving the Southwest, and the result was curtailments by some of the distribution utilities, particularly in New Mexico, representatives from Transwestern and El Paso Natural Gas pipeline units told a U.S. Senate energy committee informational hearing Monday in Albuquerque, NM.

While sub-zero temperatures across the region sent demand skyrocketing, the same brutal weather froze gas production equipment in Texas and New Mexico, making it difficult for the two interstate pipelines to get the added supplies needed into their pipelines to avoid the service disruption to end-users, the two pipeline executives told Sen. Jeff Bingaman, chairman of the Energy and Natural Resources Committee, during the three-hour hearing.

"Recent extreme weather conditions restricted supplies flowing into the pipeline at the very time that shippers were requesting dramatic increases in supplies," said Shelley Corman, a senior vice president at Transwestern, which has 48 receipt points on its pipeline in New Mexico, with 10 of those going to New Mexico Gas Co., the utility that was forced to curtail more than 27,000 of its customers spread in rural areas across the northern part of the state.

In the midst of the worst of the freeze on Feb. 2, an excess of about 400 million MMBtu of gas supplies was being taken out of Transwestern's pipelines, compared to the volumes going into the pipeline, resulting in pressure drops and the overall volumes in the pipeline (line pack) were reduced, Corman said. "Despite these circumstances, we kept our pressures above our contractual minimum operating pressures."

Janice Parker, vice president for customer service with El Paso's Western Pipeline Group, said early in the morning on Feb. 2, El Paso noticed that it was not getting the supplies it needed from the Permian Basin. At the time, El Paso's suppliers were reporting rolling blackouts and freezeoffs at processing sites that were preventing them from sending their gas to the pipeline.

"At the same time, because of the extreme cold weather, our customers were taking much more gas than was coming into our pipelines," Parker said. As a result, she said the southern pipeline system's linepack increasingly showed signs of depletion -- first in the El Paso, TX, area, then in the Alamogordo, NM, area and finally around Tucson, AZ.

Overall, El Paso was able to deliver all of the gas that its suppliers were able to get into its pipelines, along with another 20% in added supplies that it obtained, Parker said. While the pipeline did lose electrical power to some of its compressor stations due to the cold weather, it had backup power supplies and was able to keep all of its stations operating, she said.

Corman said Transwestern had more than enough pipeline capacity to meet its shippers' delivery requests, and there was no compression or transmission outage on its system that hindered the interstate pipeline's ability to receive or deliver gas to shippers in New Mexico. She said the pipeline's gas control people worked around the clock with their counterparts at New Mexico Gas to maintain pressures.

"We do not have any first-hand knowledge of why particular supplies were not received as planned," Corman said. "Nor do we fully understand whether there were any downstream operating conditions that prevented shippers [such as New Mexico Gas] from taking gas at lower line pressures. The extreme temperatures created many difficulties for the gas industry, and industries that support it.

"We believe Transwestern used all the tools under its control to maximize the gas available at New Mexico delivery points."

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