Economic recovery of marginal offshore gas

Transportation of 10.7 million cu ft/day of natural gas compressed to 2400 psi by barge from a reservoir 15 mi from the nearest offloading point would require total operating costs of $1.191/1000 cu ft, as compared with $2.749/1000 cu ft by pipeline, assuming 8 billion cu ft of reserves. Two or three barges moved by tugs at 9 knots max would contain 12 vessels holding 300,000 cu ft each of gas and be able to operate in waves up to 8 ft high. It is entirely feasible that barge transportation of natural gas will be implemented in the Gulf of Mexico within two years. A urea plant using 43 million cu ft/day of natural gas to produce 1755 tons/day of urea about 100 mi offshore of a developing nation would require a $149 million capital investment, fixed operating costs of $30 million/yr, and total variable operating costs of $40,000/day, assuming a water depth of 180 ft, a wave height of 52 ft max, a wind speed of 100 knots max, and a 2.5% product loss. The best design would involve a jackup platform and passing a 75% solution at 240/sup 0/F to a barge for finishing into solid products.