Steamflood expansion includes liquid redox process

Jan. 29, 1996
Chevron U.S.A. Production Co. will install a liquid redox process to sweeten associated gas containing H2S from its Cymric cyclic steamflood, Kern County, Calif. The treated natural gas will be used as fuel for steam flooding and other operations. The process replaces the current method of burning gas in 50 MMBTU steam generators and using caustic to scrub SO2 from the stack gas. Chevron says the present system does not provide the needed flexibility for its planned expansion of the field.

Chevron U.S.A. Production Co. will install a liquid redox process to sweeten associated gas containing H2S from its Cymric cyclic steamflood, Kern County, Calif. The treated natural gas will be used as fuel for steam flooding and other operations.

The process replaces the current method of burning gas in 50 MMBTU steam generators and using caustic to scrub SO2 from the stack gas.

Chevron says the present system does not provide the needed flexibility for its planned expansion of the field.

Chevron selected Dow Chemical Co.'s SulFerox (a registered service mark of Shell Oil Co.) liquid redox technology. The process (Fig. 1) uses an iron chelate that undergoes reduction-oxidation reactions to convert H2S to elemental sulfur.

Start-up of the redox unit is expected in May or June 1996, and it will initially process 3-4 MMcfd of associated gas from 90 wells. The throughput will later increase to the design capacity of 8.2 MMcfd after drilling about 130 additional wells. About 1 MMcfd of the gas stream will come from a casinghead gas and vapor-recovery unit gathering system that connects several thousand wells.

The associated gas contains approximately 4,000 ppm H2S and the casinghead-gas gathering system 6,000-7,000 ppm H2S. The combined gas stream entering the redox unit will have about 4,800 ppm H2S. The redox unit is expected to produce 1.5 long tons/day of sulfur and decrease H2S in the gas to less than 4 ppm.

The first stage of a three-stage compressor will compress the associated gas from about 25 psi to the redox unit operating pressure of 60-70 psi.

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