Author: haroonkhan
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Introduction
At the beginning of this text, the various hydrocarbon reservoirs were subdivided into four types. This contains a discussion on reservoirs that have only liquid phases initially present. The will consider oil reservoirs that have an initial gas cap. These two reservoir types differ significantly from the gas reservoirs. The differences stem from the composition…
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Use of Nitrogen for Pressure Maintenance
One of the major disadvantages associated with the use of lean gas in gas-cycling applications is that the income that would be derived from the sale of the lean gas is deferred for several years. For this reason, the use of nitrogen has been suggested as a replacement for the lean gas.16 However, one might expect…
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Lean Gas Cycling and Water Drive
Because the liquid content of many condensate reservoirs is a valuable and important part of the accumulation and because through retrograde condensation a large fraction of this liquid may be left in the reservoir at abandonment, the practice of lean gas cycling has been adopted in many condensate reservoirs. In gas cycling, the condensate liquid…
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Comparison between the Predicted and Actual Production Histories of Volumetric Reservoirs
Allen and Roe have reported the performance of a retrograde condensate reservoir that produces from the Bacon Lime Zone of a field located in East Texas.13 The production history of this reservoir is shown in Figs. 5.6 and 5.7. The reservoir occurs in the lower Glen Rose Formation of Cretaceous age at a depth of 7600 ft (7200 ft…
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Use of Material Balance
The laboratory test on the retrograde condensate fluid in Example 5.3 is itself a material balance study of the volumetric performance of the reservoir from which the sample was taken. The application of the basic data and the calculated data of Example 5.3 to a volumetric reservoir is straightforward. For example, suppose the reservoir had produced 12.05 MMM SCF of gross…
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The Performance of Volumetric Reservoirs
The behavior of single-phase gas reservoirs is treated. Since no liquid phase develops within the reservoir, where the temperature is above the cricondentherm, the calculations are simplified. When the reservoir temperature is below the cricondentherm, however, a liquid phase develops within the reservoir when pressure declines below the dew point, owing to retrograde condensation, and…
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Calculating Initial Gas and Oil
The initial gas and oil (condensate) for gas-condensate reservoirs, both retrograde and nonretrograde, may be calculated from generally available field data by recombining the produced gas and oil in the correct ratio to find the average specific gravity (air = 1.00) of the total well fluid, which is presumably being produced initially from a one-phase…
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Introduction
Gas-condensate production may be thought of as intermediate between oil and gas. Oil reservoirs have a dissolved gas content in the range of zero (dead oil) to a few thousand cubic feet per barrel, whereas in gas reservoirs, 1 bbl of liquid (condensate) is vaporized in 100,000 SCF of gas or more, from which a…
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Limitations of Equations and Errors
The precision of the reserve calculations by the volumetric method depends on the accuracy of the data that enter the computations. The precision of the initial gas in place depends on the probable errors in the averages of the porosity, connate water, pressure, and gas deviation factor and in the error in the determination of…
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Abnormally Pressured Gas Reservoirs
Normal pressure gradients observed in gas reservoirs are in the range of 0.4 to 0.5 psi per foot of depth. Reservoirs with abnormal pressures may have gradients as high as 0.7 to 1.0 psi per foot of depth.14,15,16,17 Bernard has reported that more than 300 gas reservoirs have been discovered in the offshore Gulf Coast alone,…