Category: Undersaturated Oil Reservoirs

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… Continue reading Calculations, Including Formation and Water Compressibilities

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… Continue reading The Gloyd-Mitchell Zone of the Rodessa Field

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… Continue reading Kelly-Snyder Field, Canyon Reef Reservoir

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… Continue reading Material Balance in Undersaturated Reservoirs

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… Continue reading Calculating Oil in Place and Oil Recoveries Using Geological, Geophysical, and Fluid Property Data

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… Continue reading Oil Reservoir Fluids

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… Continue reading Introduction