The history of primary production and the onset of co-production from the Frio 9100 sand at the N.E. Hitchcock reservoir was previously described by L. Anderson.1 This paper summarizes co-production recovery since its onset in 1983 and then provides details of current operating characteristics for three wells at locations on the structure that result in quite different producing characteristics.
High brine rate production at the Prets Unit No. 1 well commenced three years ago. The produced gas/brine ratio of about 240 SCF/STB provides sufficient natural lift to maintain flow of about 4400 STB/D of brine, 55 STB/D of oil and 1050 MCF/D of gas through 2-7/8 inch tubing.
The other two wells are structurally lower and are being produced with artificial lift to achieve brine rates in the range of 4200 to 5000 STB/D. Produced gas/brine ratios are about 90 SCF/STB and 45 SCF/STB and oil production is similarly less than for the Prets well.
Surface equipment and operating procedures being used for secondary recovery of gas previously trapped by imbibition during primary production are described.