Author: haroonkhan
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Continuous Uniform Formations
Continuous uniform formations reduce the channeling of the expanding gas cap ahead of the oil and the bypassing of oil in the less permeable portions.
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Large Gas Caps
The size of the gas cap is usually expressed relative to the size of the oil zone by the ratio m.
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Factors Affecting Overall Recovery
In gas-cap drives, as production proceeds and reservoir pressure declines, the expansion of the gas displaces oil downward toward the wells. This phenomenon is observed in the increase of the gas-oil ratios in successively lower wells. At the same time, by virtue of its expansion, the gas cap retards pressure decline and therefore the liberation…
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Introduction
The final reservoir type is the saturated oil reservoir and is distinguished by the presence of both liquid and gas in the reservoir. The material balance equations for undersaturated oil reservoirs, apply to volumetric and water-drive reservoirs in which there are no initial gas caps. However, the equations apply to reservoirs in which an artificial…
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Calculations, Including Formation and Water Compressibilities
It was shown that both formation and water compressibilities are functions of pressure. This suggests that there are in fact no volumetric reservoirs—that is, those in which the hydrocarbon pore volume of the reservoir remains constant. Hall showed the magnitude of the effect of formation compressibility on volumetric reservoir calculations.18 The term volumetric, however, is retained to…
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The Gloyd-Mitchell Zone of the Rodessa Field
Many reservoirs are of the volumetric undersaturated type and their production, therefore, is controlled largely by the solution gas-drive mechanism. In many cases, the mechanism is altered to a greater or lesser extent by gravitational segregation of the gas and oil, by small water drives, and by pressure maintenance, all of which improve recovery. The…
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Kelly-Snyder Field, Canyon Reef Reservoir
The Canyon Reef reservoir of the Kelly-Snyder Field, Texas, was discovered in 1948. During the early years of production, there was much concern about the very rapid decline in reservoir pressure; however, reservoir engineers were able to show that this was to be expected of a volumetric undersaturated reservoir with an initial pressure of 3112…
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Material Balance in Undersaturated Reservoirs
The material balance equation for undersaturated reservoirs was developed: Neglecting the change in porosity of rocks with the change of internal fluid pressure, which is treated later, reservoirs with zero or negligible water influx are constant volume or volumetric reservoirs. If the reservoir oil is initially undersaturated, then initially it contains only connate water and…
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Calculating Oil in Place and Oil Recoveries Using Geological, Geophysical, and Fluid Property Data
One of the important functions of the reservoir engineer is the periodic calculation of the reservoir oil (and gas) in place and the recovery anticipated under the prevailing reservoir mechanism(s). In some companies, this work is done by a group that periodically renders an account of the company’s reserves together with the rates at which…
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Oil Reservoir Fluids
Oil reservoir fluids are mainly complex mixtures of the hydrocarbon compounds, which frequently contain impurities such as nitrogen, carbon dioxide, and hydrogen sulfide. The composition in mole percentages of several typical reservoir liquids is given in Table 6.1, together with the tank gravity of the crude oil, the gas-oil ratio of the reservoir mixture, and other…