DENVER-Western Gas Partners LP's Lancaster facility in the Denver-Julesburg Basin was fully commissioned in mid-2015 with two "dual-mode" gas processing trains, each with a capacity of 300 million cubic feet a day. The dual-mode trains are designed to provide maximum operating flexibility, allowing very high ethane recovery when desired, but also maintaining very high propane recovery when ethane rejection is more economical. This rich-gas process design is based on advanced Single Column Overhead Recycle (SCORE) and Supplemental Rectification with Compression (SRC) licensed process technologies. Since commissioning, operation has been primarily in the ethane rejection mode, with significant positive revenue results achieved by rejecting 99 percent of the ethane to the residue gas stream while maintaining 99 percent propane recovery. In addition, the processing uses significantly less compression horsepower than would be required with an "open-art" plant design. MARCH 2017 55