Sunoco Logistics Partners LP, which operates pipelines and terminals, is poised to export the first U.S. waterborne ethane cargo “within a week,” according to Genscape Inc. The company’s Mariner East 1 pipeline, which stretches from the Marcellus shale deposit in western Pennsylvania to the Marcus Hook terminal on the Delaware River near Philadelphia, boosted ethane deliveries on Feb. 22, said Amanda Townsley, senior adviser of petrochemicals and LNG for Genscape, which is monitoring the line.  The jump in flows coincides with the arrival of the terminal’s first tanker, the JS Ineos Intrepid, at the ethane dock, she said.  This ethane is contracted to go to Norway as feedstock at processing plants owned by Ineos Europe AG, and will ultimately be used to make products such as plastic. U.S. producers have seen prices for natural gas and liquids tumble as output from shale deposits outpaces demand. “The first ship at the ethane dock is exciting; this would be the first waterborne export from the U.S. period,” Townsley, based in Houston, said in a telephone interview. “It’s not a massive volume so it’s not a game changer for the supply and demand balance, but it’s a big deal for the producers in the area.” Range Resources Corp. is contracted to ship 20,000 barrels of ethane on the pipeline to the Philadelphia area terminal, according to its website. Ineos previously announced it also has a long-term contract to purchase ethane from Consol Energy Inc. Sunoco Logistics spokesman Jeffrey Shields declined to provide updates and said to listen to the company’s earnings call early Thursday for any developments, according to an e-mail Tuesday. He didn’t respond to requests for comment on Wednesday.