Average Reservoir Pressure Why is this Important?
Bellows[ edit ] A pile of pressure capsules with corrugated diaphragms in an aneroid barograph In gauges intended to sense small pressures or pressure differences, or require that an absolute pressure be measured, the gear train and needle may be driven by an enclosed and sealed bellows chamber, called an aneroid, which means "without liquid".
Early barometers used a column of liquid such as water or the liquid metal mercury suspended by a vacuum. This bellows configuration is used in aneroid barometers barometers with an indicating needle and dial cardaltimetersaltitude recording barographsand the altitude telemetry instruments used in weather balloon radiosondes.
These devices use the sealed chamber as a reference pressure and are driven by the external pressure. Other sensitive aircraft instruments such as air speed indicators and rate of climb indicators variometers have connections both to the internal part of the aneroid chamber and to an external enclosing chamber.
Magnetic coupling[ edit ] These gauges use the attraction of two magnets to translate differential pressure into motion of a dial pointer. As differential pressure increases, a magnet attached to either a piston or rubber diaphragm moves.
A rotary magnet that is attached to a pointer then moves in unison. To create different pressure ranges, the spring rate can be increased or decreased. Spinning-rotor gauge[ edit ] The spinning-rotor gauge works by measuring the amount a rotating ball is slowed by the viscosity of the gas being measured.
The ball is made of steel and is magnetically levitated inside a steel tube closed at one end and exposed to the gas to be measured at the other. It is accurate and stable enough to be used as a secondary standard.
The instrument requires some skill and knowledge to use correctly. Various corrections must be applied and the ball must be spun at a pressure well below the intended measurement pressure for five hours before using.
It is most useful in calibration and research laboratories where high accuracy is required and qualified technicians are available. Pressure sensor Piezoresistive strain gage Uses the piezoresistive effect of bonded or formed strain gauges to detect strain due to applied pressure.
Capacitive Uses a diaphragm and pressure cavity to create a variable capacitor to detect strain due to applied pressure.
Magnetic Measures the displacement of a diaphragm by means of changes in inductance reluctanceLVDTHall effector by eddy current principle.
Piezoelectric Uses the piezoelectric effect in certain materials such as quartz to measure the strain upon the sensing mechanism due to pressure. Optical Uses the physical change of an optical fiber to detect strain due to applied pressure.
Potentiometric Uses the motion of a wiper along a resistive mechanism to detect the strain caused by applied pressure. Resonant Uses the changes in resonant frequency in a sensing mechanism to measure stress, or changes in gas density, caused by applied pressure. Thermal conductivity[ edit ] Generally, as a real gas increases in density -which may indicate an increase in pressure - its ability to conduct heat increases.
In this type of gauge, a wire filament is heated by running current through it. A thermocouple or resistance thermometer RTD can then be used to measure the temperature of the filament.
This temperature is dependent on the rate at which the filament loses heat to the surrounding gas, and therefore on the thermal conductivity.
A common variant is the Pirani gaugewhich uses a single platinum filament as both the heated element and RTD. Pirani one wire [ edit ] Main article: Pirani gauge A Pirani gauge consist of a metal wire open to the pressure being measured.
The wire is heated by a current flowing through it and cooled by the gas surrounding it.This extrpolated value, a false pressure, p*, can be considerably different from the average reservoir pressure.
It is necessary to calcuate the average pressure from relationships between the false pressure and the average reservoir pressure. The pressure that would be obtained if all fluid motion ceases in a given volume of reservoir.
It also is the pressure to which a well will ultimately rise if . B. Average reservoir pressure for simulation results given in A. C. CO 2 injection rate as a function of time determined from TOUGH2 simulator results, using multiple permeability and porosity realizations.
D. Average reservoir pressure for simulation results given in C. The average reservoir pressure in a reservoir at a given time is an indication of how much fluid (gas, oil, or water) is remaining in the reservoir.
It represents the amount of driving force available to drive the remaining fluid out of . Abstract. Saturated gas drive reservoirs are characterized by rapid and continuous decline of reservoir pressure.
The resultant effect of this phenomenon is the early decline of reservoir performance at the primary stage of the life of the reservoir. Miller-Dyes-Hutchinson presented a method for calculating the average reservoir pressure, T, in in This method requires pseudosteady state before shut-in and was at first restricted to a circular reservoir with a centrally located well.