Ato mic-absorption determination of vanadium and nickel in gas oil fractions of crude oils: L. M. Zamilova, T. G. Biktimirova and V. I. Sokolova, Neftekhimiya 25, No. 2, 159–162, 1982

Abstract

This chapter describes the gas from conventional gas fields. Conventional gas reservoirs should be defined upon the basis of the location of their initial reservoir pressure and temperature on the usual pressure–temperature (P–T) diagram. The phase envelope is bounded by the dew point and bubble-point lines converging at the critical point. At all P–T conditions enclosed within these boundaries, two phases, vapor and liquid, coexist. Utilizing the P–T diagram, petroleum reservoirs may be instantly characterized as gas, gas-condensate, or oil. Considering an initial reservoir condition at A, the pressure history of such a reservoir by normal depletion would be along the path A–A. A single phase reservoir fluid would exist throughout the history of production. Also the composition of the fluid produced will remain constant. These conditions will persist for gas reservoirs having initial temperatures exceeding the cricondentherm. It is evident that the fluid produced at surface conditions may be single phase or two phases depending upon the surface P–T conditions. As reservoir pressure is reduced further along path, B2–B3 revaporization of the retrograde liquid occurs and decreasing surface gas-oil ratios are observed.