EFFECT OF SMALL SAMPLING AND MEASUREMENT ERRORS ON GAS PRODUCTION AND EMISSIONS PREDICTIONS

摘要

Laboratory measurements such as Gas-Oil Ratio, True Vapor Pressure, and compositional analyses are often used to calculate emissions from storage tanks and estimate gas production from well-sites. These measurements are based on a pressurized-liquid sample collected from a separator. Since the liquid sample is collected directly from a separator, it should be very near its bubble point, which means that any slight reduction in pressure will cause vapor to form. This vapor will predominantly consist of the lighter components from the liquid, which if allowed to escape will leave a less volatile liquid behind. The pressurized-liquid sample collection apparatus, and subsequent laboratory techniques, are designed to prevent vapor formation and loss, but if not used properly can allow vapor to escape. This paper explores how small vapor losses from both high- and low-pressure separator liquid samples can effect predictions of emissions and gas production. This paper also investigates how the presence of purge gas in a laboratory GOR apparatus can increase the measured GOR.