A New Depletion-Performance Correlation for Gas-Condensate Reservoir Fluids

Abstract

This paper presents the depletion-performance correlations developed using data from PVT studies and wellcompletion tests of 27 rich gas-condensate and volatileoil reservoir fluids. The PVT behavior for each fluid was determined experimentally in the laboratory, and the depletion performance of each fluid was then calculated. Well-completion test data consisting of reservoir pressure and temperature, initial total gas-oil ratio, and stock-tank oil gravity were used with the depletion-performance data to develop general performance correlations.Three correlations are presented. The first equation shows the empirical relation of gas in place per barrel of hydrocarbon pore space with reservoir pressure and temperature, and initial total gas-oil ratio. The second equation is the correlation of stock-tank oil in place per barrel of hydrocarbon pore space. The third equation relates stock-tank oil production (to 500-psia depletion pressure) with pressure, temperature and oil gravity. All three correlations are also presented in convenient graphical form. Gas production to 500-psia depletion pressure is approximately 92.6 per cent of the gas in place for each fluid, so no correlation was developed for gas production.

Calculation Method of the Phase Recovery of Gas Cap Reservoir with Bottom Water

“…Simulation calculations were conducted by using tNavigator simulation software to simulate the mechanism model of gas-cap and bottomwater reservoirs, and some results of the calculations are shown in Table 3: The actual output of gas is split into two parts, which are the gas from the cap and dissolved gas; the output oil is oil-rim oil. According to the law of mass conservation, using the daily gas-oil production, the daily oil-rim oil production q o1 , the daily dissolved gas production q g1 , and the daily gas-cap gas production q g2 were calculated by combining Equation ( 16), Equation (17), and Equation (18), respectively, and the dissolved gas reserve G s1 was calculated by utilizing Equation (19), and the daily production of sub-phases was totaled and calculated with the original reserves of each sub-phase by utilizing Equations ( 20)- (22) to obtain the extraction levels of gas-cap gas, oil-rim oil, and dissolved gas at different pressures, respectively. The recovery levels of gas cap, oil rim, and dissolved gas at different pressures were obtained.…”

“…The commonly used methods for calculating the recovery include empirical formulae and analytical methods. In 1965,Eaton B A and Jacoby R H proposed an empirical formula for the recovery of condensate with a condensate content of 73-400 g/m 3 and the use of depletion type extraction by studying the basic parameters of 27 condensate reservoirs in the U.S.A. [22]. In 2005, C.S.…”