Commercially viable production of 150 SCF/STB (27 m3/m3) of gas per barrel of brine has been achieved for reservoir pressure substantially below hydrostatic. Reservoir pressure at 9100 feet (2 990 m) has been drawn down to below 3460 psi (23 620 kPa) or 0.380 psi per foot (0.085 1 kPa/cm). Those wells having a gas/brine ratio in excess of 100 SCF/STB (18 m3/m3) flow because of lift by produced gas. Injection of lift gas is used 1) to start production after wells are shut-in, 2) to maintain production for lower gas/brine ratios, and 3) to increase rate or to increase wellhead pressure for operation of the surface facilities.

Key features of the well completions and surface facilities to maximize recovery are:

  • Minimizing friction losses by 1) using annular production, 2) installing tubing only to the depth required for gas lift and chemical injection, 3) using large-diameter wellhead valves and downstream piping, and 4) injecting scale inhibitor through chemical treat strings.

  • Utilizing freewater knockouts followed by separate oil-gas separators that facilitate cooling of condensate before placing it into the stock tanks. This minimizes evaporative loss.

  • Keeping operating costs low by 1) maintaining brine pressure above atmospheric to keep oxygen out of the system and to reduce disposal pumping costs, 2) creating large sand surface areas in the disposal zones to reduce the injection pressure, and 3) using the same compressor for both gas lift and gas sales.

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