Author: haroonkhan
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Gas Reservoirs as Storage Reservoirs
The demand for natural gas is seasonal. During winter months, there is a much greater demand for natural gas than during the warmer summer months. To meet this variable demand, several means of storing natural gas are used in the industry. One of the best methods of storing natural gas is with the use of…
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The Gas Equivalent of Produced Condensate and Water
In the study of gas reservoirs in the preceding section, it was implicitly assumed that the fluid in the reservoir at all pressures as well as on the surface was in a single (gas) phase. Most gas reservoirs, however, produce some hydrocarbon liquid, commonly called condensate, in the range of a few to a hundred or more…
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Material Balance in Water-Drive Gas Reservoirs
In water-drive reservoirs, the relation between Gp and p/z is not linear, as can be seen by an inspection of Eqs. (4.13) and (4.16). Because of the water influx, the pressure drops less rapidly with production than under volumetric control, as shown in the upper curve of Fig. 4.2. Consequently, the extrapolation technique described for volumetric reservoirs is not applicable.…
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Material Balance in Volumetric Gas Reservoirs
For a volumetric gas reservoir, Eq. (4.13) can be reduced to a simple application of a straight line involving the gas produced, its composition, and the reservoir pressure. This relationship is routinely used by reservoir engineers to predict recoveries from volumetric reservoirs. Since there is neither water encroachment nor water production in this type of…
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Calculating Gas in Place Using Material Balance
In the previous sections, the initial gas in place was calculated on a unit basis of 1 ac-ft of bulk productive rock, given information on the porosity and connate water. To calculate the initial gas in place on any particular portion of a reservoir, it is necessary to know, in addition, the bulk volume of…
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Calculating Unit Recovery from Gas Reservoirs under Water Drive
Under initial conditions, one unit (1 ac-ft) of bulk reservoir rock contains Connate water: 43,560 × φ × Swi ft3 Reservoir gas volume: 43,560 × φ × (1 – Swi) ft3 Surface units of gas: 43,560 × φ × (1 – Swi) ÷ Bgi SCF In many reservoirs under water drive, the pressure suffers an initial decline, after which water enters the reservoir at a…
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Calculating Unit Recovery from Volumetric Gas Reservoirs
In many gas reservoirs, particularly during the development period, the bulk volume is not known. In this case, it is better to place the reservoir calculations on a unit basis, usually 1 ac-ft of bulk reservoir rock. This one unit, or 1 ac-ft, of bulk reservoir rock contains Connate water: 43,560 × φ × Sw ft3 Reservoir gas volume:…
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Calculating Hydrocarbon in Place Using Geological, Geophysical, and Fluid Property Data
In order for the reservoir engineer to calculate the amount of hydrocarbon in place from geological information, the reservoir bulk volume must first be calculated. Many methods exist to estimate the reservoir bulk volume but only two will be discussed here. The first method involves the reservoir engineer using well logs, core data, well test…
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Introduction
The contains a discussion of single-phase gas reservoirs (refer to Fig. 1.4). In a single-phase gas reservoir, the reservoir fluid, usually called natural gas, remains as nonassociated gas during the entire producing life of the reservoir. This type of reservoir is frequently referred to as a dry gas reservoir because no condensate is formed in the…
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The Havlena and Odeh Method of Applying the Material Balance Equation
As early as 1953, van Everdingen, Timmerman, and McMahon recognized a method of applying the material balance equation as a straight line.9 But it wasn’t until Havlena and Odeh published their work that the method became fully exploited.3,4 Normally, when using the material balance equation, an engineer considers each pressure and the corresponding production data as being separate…