CLASS 06
BALANCE OF MATERIALS FOR GAS FIELDS
As was already discussed in class 01, the gas fields can be of three types: dry gas, wet gas or condensate.
To study their behavior is also possible to apply the principle of material balance, where the emptying of the reservoir is equal to the amount of support from all production mechanisms in the subsurface. There are two ways to analyze and determine the properties of gases, studying them as real or ideal, method simplifying the work and you closer to the actual behavior of gas.
If you want to consider an ideal gas as is necessary: \u200b\u200btheir molecules do not present internal collisions, that the forces of attraction and repulsion between them are negligible and that a mole of gas contains always the same number of molecules, which occupy the same volume, under specified conditions of pressure and temperature. From this we have established principles and laws apply to this idealizing if you study a fixed amount of gas.
Boyle's Law: At a specific temperature
happens that
P * V = constant.
Avogadro's Law: At a specific temperature and pressure
Charles Law: A specific pressure
Considering the above statements is possible to observe the relationship between variables P, V and T. This will get the equation of state of ideal gases
As expected, since the ideal gas model very well the behavior of real gases under certain conditions, then treatment should actually not be very different. For real gases is known that the particles are in constant motion and thus may collapse between them and the forces of attraction and repulsion have an appreciable value.
Because it is necessary to consider a parameter that encompasses these features and help us to model this type of gases. For that we work with the gas compressibility factor (Z). The equation is this:
According to the principle of states correspodientes, all gases have, at the same pressure and temperature, the value Z in common. This value can be found experimentally diviendo real gas volume between the volume that would occupy ideally, at the same pressure and temperatura.Teóricamente there are two methods to obtain Z:
According to Van Der Waals, 1856, Z a function of reduced temperature and pressure of a pure gas.
Rule Kay, 1936, for mixtures.
After obtaining these values, making use of the compressibility factor graphs of Standing and Katz and generalized compressibility chart, you can get the value of Z. We enter the x-axis with the value of PSR or Pr and cut to the corresponding asymptote to Tsr or Tr, reading in the shaft and the value of Z.
Returning to the theme of Material Balance for a gas field.
Mi - Mf Mp + Me =
where
Mi = initial mass.
Mp = mass produced.
Me = mass input.
Mf = final mass.
GOES can be found by analytical methods or the volumetric method volumétricos.Con have:
To derive the EBM for this type of deposits is required to balance on the original volume, the volume pores available and the number of moles.En this point would be advisable to consider the conditions of the site. If the reservoir is a volume, then
If the equation is continuous and is known cheese can generally get
When the reservoir volume is then one way to know the GOES is to apply the method recta.Si line shows the case of a wet gas field where liquid condensation occurs during the movement pipeline due to the change of temperature and pressure conditions will cause a certain amount on the surface of the liquid, but should be counted as part of the GP, since this reservoir conditions was also in the gas phase. For this
and that volume is added to the gas produced in order to implement EBM and encontrr GOES.
