Formation volume factor equation

The above equation introduces two new properties of the oil, the formation volume factor and the solution gas oil ratio, which will now be explained. 

The flowrate of oil into the wellbore is also influenced by the reservoir properties of permeability (k) and reservoir thickness (h), by the oil properties viscosity (p) and formation volume factor (BJ and by any change in the resistance to flow near the wellbore which is represented by the dimensionless term called skin (S). For semisteady state f/owbehaviour (when the effect of the producing well is seen at all boundaries of the reservoir) the radial inflow for oil into a vertical wellbore is represented by the equation ... 

The equations for the formation volume factor of gas, Equations 6-2 and 6-3, only apply to dry gases. These equations are not applicable to wet gases. 

Direct substitution of formation volume factor of oil into the first of Equations 8-7 results in... 

Gas formation volume factors are calculated with z-factors measured with the gases removed from the cell at each pressure step during differential vaporization. Equation 6-2 is used. Usually Bg values as calculated are listed in the report. 

The normal procedure for estimating formation volume factor at pressures above the bubble point is first to estimate the factor at bubble-point pressure and reservoir temperature using one of the methods just described. Then, adjust the factor to higher pressure through the use of the coefficient of isothermal compressibility. The equation used for this adjustment follows directly from the definition of the compressibility coefficient at pressures above the bubble point. 

The equation will be developed below. The formation volume factor may be calculated as... 

Step 6 Calculate formation volume factor using Equation 13-9. 

The change in volume during the pressure reduction is represented by AV, and the change in volume due to the reduction in temperature is represented by AV. Figures 16-6 and 16-7 give values of AVwp and AVwX as functions of reservoir temperature and pressure. The formation volume factor of water may be computed from these values using Equation 16-1. 

The formation volume factor of water, Bw, is computed with Equation 16-1 and Figures 16-6 and 16-7. 

The formation-volume factor of gas, Bg, is calculated using Equation 6-3. Use a value of 0.63 for the specific gravity of the gas evolved from the water to determine a z-factor for Equation 6-3. This value is based on limited data and its accuracy is unknown however, it gives values which appear reasonable. 

The Gas-Formation Volume Factor. The gas laws discussed in Chapter 2 may be employed to calculate the number of barrels of reservoir space occupied by one standard cubic foot of gas. If one standard cubic foot of gas is placed in a reservoir at reservoir pressure Pa and temperature Tq the following equation is valid provided the gas remains in the gaseous state. 

In engineering calculations the formation volume factor /3 is most commonly used to express the change in liquid volume with pressure. / is defined by equation 4 or by an equivalent definition as the volume... 

Obviously, this equation can be used to calculate the formation volume factor at any pressure P2 above the saturation pressure provided C... 

The Two-Phase Formation Volume Factor (u). In reseiwou engineering calculations it is sometimes convenient to know the volume occupied in the reservoir by one stock tank barrel of oil plus the free gas that was originally dissolved in it. This volmne is known as the two-phase fomation volume factor and is ven the symbol u. It is apparent that the value of u is determined by the values of the reservoir fluid characteristics previously described. Expressed mathematically M is defined by the following equation... 

The concept of the two-phase formation volume factor is introduced mainly for convenience. As will be shown in the next chapter, many of the frmdamental reservoir equations are simplified if ey are expressed in terms of %. 

Recalling the deflnition of the two-phase formation volume factor u, this equation becomes... 

It is evident that equation 3 is a special case of equation 6 since equation 6 reduces to equation 3 when m and W — w are both equal to zero. Furthermore, it should be noted that in the derivation of equation 6 the water-formation volume factor and solubility of gas in water were not considered. This is in keeping with the results described in Chapter 6 since in most instances these effects are small and may be neglected. 

Hence the dimension ("the order") of the reaction is different, even in the simplest case, and hence a comparison of the two rate constants has little meaning. Comparisons of rates are meaningful only if the catalysts follow the same mechanism and if the product formation can be expressed by the same rate equation. In this instance we can talk about rate enhancements of catalysts relative to another. If an uncatalysed reaction and a catalysed one occur simultaneously in a system we may determine what part of the product is made via the catalytic route and what part isn t. In enzyme catalysis and enzyme mimics one often compares the k, of the uncatalysed reaction with k2 of the catalysed reaction if the mechanisms of the two reactions are the same this may be a useful comparison. A practical yardstick of catalyst performance in industry is the space-time-yield mentioned above, that is to say the yield of kg of product per reactor volume per unit of time (e.g. kg product/m3.h), assuming that other factors such as catalyst costs, including recycling, and work-up costs remain the same. 

Inhibition of H2 formation can be seen when the anode-volume is saturated with O2 application of an external bias up to 0.7 V can usually prevent this effect, increased yield of H2 when Pt is present as a cathode has been rationalized in terms of three factors (a) the removal of conduction band electron from Ti02 to Pt [equation (4.4.14)], (b) The ease of reactions (4.4.15) and (4.4.16) because of a low overpotential for H2 evolution from water at the Pt cathode, and (c) H atom migration to the Pt cathode. 

The transformation of smectite to mixed layer smectite-illite, and ultimately to illite, with increasing temperature is an extremely important reaction in many sedimentary basins, including the northern Gulf of Mexico Basin (Hower et al., 1976 Boles and Franks, 1979 Kharaka and Thordsen, 1992). The water and solutes released and consumed by this transformation are major factors in the hydrogeochemistry of these basins, because of the enormous quantities of clays involved. Several reactions conserving aluminum or maintaining a constant volume have been proposed for this transformation (Hower et al., 1976 Boles and Franks, 1979). The reaction proposed below (Equation (4)) conserves aluminum and magnesium, and is probably a closer approximation based on the composition of formation waters in these systems ... 

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