ARCO builds major carbon dioxide line

In 1972, leaseholders exploring for natural gas near Walsenburg, Colo., found their first wells producing CO2 instead of gas. ARCO Oil and Gas Co. had 2 oil fields in Texas for which it felt the CO2 could be used for enhanced oil recovery. If the gas could be transported to these fields (the Wasson and Seminole fields located in Yoakum and Gaines counties), as much as 25% of the remaining oil in place could be recovered using the CO2 for tertiary miscible flooding. ARCO purchased the leases from the original holders in 1974 and continued development of the Sheep Mt. Unit. Today the field consists of ca 9,000 acres. Producing the CO2 posed no speical problems for ARCO since the recovery and production facilities were similar in design and construction to those used for natural gas. However, there were several different options available to transport the CO2. Based on the volumes needed for enhanced recovery and the production capabilities within the Sheep Mt. Unit, it was decided a pipeline would be the most economical mode of transport for the estimated 330 MMscfd that would be produced. A 405-mile line was required for delivery.