A dry gas sample has been extracted from a well and analyzed via GC to have the following mole fractions: 0.91 methane, 0.04 ethane, 0.035 propane, and 0.015 n-butane. The well temperature is 140°F and the well pressure is 1950 psia.
- What is the gas gravity?
- Assuming a compressibility of 0.8, what is the gas formation volume factor at reservoir conditions?
- If the gas sample was taken at a depth of 4200 ft, and the regional aquifer gradient is 0.44 psi/ft, what is the depth of the gas liquid contact?
- If the crest of the trap was 900 ft above the gas-liquid contact, what density of drilling mud is necessary to control formation pressure at the crest with 500 psi overpressure?