Determining the value of newly located natural gas sites involves estimating the gas composition, quantity, and ease of access. For example, one report described a find of 2 trillion cubic feet of natural gas that is significantly offshore, in 20 feet of water, and at a drilled depth of 25,000 ft. (In North America and the OPEC countries, reported volumes are determined at 14.73 psia and 60°F.) The pressure in this find is estimated to be 750 atm, and the gas is 94 mole% methane, 3.5% ethane, and the balance CO2.
(a) Estimate the total lb-moles of gas in the find.
(b) Use the compressibility-factor equation of state to estimate the specific volume (ft3/lb-mole) in the well. The temperature of such wells can vary depending upon a number of factors; for the purposes of this problem, assume that it is 200°C.