Historic Gulf of Mexico gas field responds to redevelopment

March 6, 2000
One of the Gulf of Mexico's oldest fields has responded positively to a redevelopment program that began last year.

One of the Gulf of Mexico's oldest fields has responded positively to a redevelopment program that began last year.

Vermilion 39 gas, oil, and condensate field, discovered in 1948, attained record production of 17,500 boe/d in the last few days of 1999. Broken out at 100.2 MMcfd of gas and 802 st-tk b/d of oil and condensate, this exceeded the previous peak of 16,700 boe/d in 1980. The yearend rate was 59.5 MMcfd and 256 b/d greater than when redevelopment began in April 1999.

Redevelopment allowed addition of more than 7 million boe of reserves, said the operator, Unocal Corp.'s Spirit Energy 76 unit. That volume is made up of 42.2 bcf of gas and 131,000 bbl of liquids. Spirit holds 100% working interest.

Cumulative production is 285 Mmboe since flow started in 1951, second start-up in the gulf. The shelf field drains parts of three blocks. It is in 40 ft of water 55 miles southwest of Lafayette and less than 10 miles off the Louisiana coast.

Minerals Management Service figures that show cumulative production of 2.4 tcf of gas and 29.4 million bbl of liquids through 1997 include production from a number of adjacent blocks, Spirit said.

Redevelopment program

Vermilion 39 redevelopment involved mainly the Miocene Cib Op, one of the field's largest sands. The sand package has three lobes, all with original gas caps and oil rims. Using 3D seismic and other data, Spirit developed a computer-generated geologic earth model and migrated that into a black oil reservoir simulation model.

The redevelopment team used the model to assess various development scenarios and incorporated surface production facilities modeling into the analysis to reach an optimized development plan. Later it used conventional earth science and engineering analysis to assess other opportunities.

Redevelopment involved drilling six new wells, working over 13 wells, and stimulating seven wells. Spirit sidetracked many of the wells from existing well bores. It also upgraded a compressor, added two, and added two pipelines.

The yearend 1999 liquids production is about 75% crude oil. Gravities are 34-57° for the oil and 47-52° for the condensate.

Vermilion 39 was the gulf's first gas and condensate field and the first to ship gas through a subsea pipeline.

Spirit Energy employs about 1,300 people and operates 300 platforms and some 2,700 active wells in 355 fields. Its net production averages 165,000 boe/d.