P z plot material balance pdf

Pdf application of general material balance on gas condensate. Material balance has not been replaced by reservoir simula tion. Plot z versus p and graphically determine the slopes at psia, 2200 psia, and 4000 psia, then, using eq. Dynamic material balance variable rate flowing pz plot the flowing material balance described above has proven to be a very successful way of determining original gas in place when the flow rate is held constant. The application of material balance equation for gas condensate reservoirs. Gas flowing material balance is the more advanced tool to determine the reservoirs giip and recovery as well as wells eur and jd. The new ratetime equations in this section, we present the explicit ratetime equations. In this case, gp is cumulative gas production, p is pressure, and z is the gas compressibility factor. Material balance calculations using the excel spreadsheet introduction material balance is a fundamental petroleum reservoir engineering tool that can be used to provide an understanding of a reservoir and the influence of any connecting aquifer. Material balance calculations using the excel spreadsheet. For a connected reservoir, the material balance equation is written as shown below to account for gas influx. For this, a more advanced form of the material balance equation has been developed, and the standard pz plot is modified to maintain a linear. A close look to the plot indicates an upward curvature of the line connecting the data points indicating water encroachment. Procedure for material balance calculations in material balance problems, you will usually be given a description of a process, the values.

General material balance for gas condensate reservoir and its. Thus, the p z plot versus gp can not be used to estimate gas in place. Once a weak waterdrive has been diagnosed, the appropriate steps can be taken in the materialbalance equations to yield more accurate results. When bgis replaced and the constants are cancelled out, the gas material balance equation then simplifies to. Material balance equations mbal software webinar mbal software speaker. This is the simplest method and does not require the set of. Material balance analysis theory fekete associates inc. This can be converted into a dimensionless term similar to the terms describing relative change in pore volume c wip, c ep, and c d for other models, as shown below. Balances on single and multiple physical systems 4. Marco mazzotti eth swiss federal institute of technology zurich separation processes laboratory spl. Which suggests plotting gp on the xaxis versus pz on the yaxis and drawing the best fit line through the set of points. W reservoir engineering manual, gulf publishing co. Usual industrial practice in pakistan is to use the pz plot to estimate the giip gas initially in place. However, there is typically very little knowledge of the effective system compressibility, meaning that this relationship is of limited practical use for reservoir engineering purposes.

Among them, ramagost and farshad1 modified the conventional material balance equation to account for pv shrinkage caused by formation and residual fluid expansion and introduced a new plotting function that keeps the material balance as a straight line. Advanced gas material balance in simplified format ihs markit. The cole plot assumes that formation compressibility can be neglected, which is frequently the case with gas. Thus setting p z 0 in the bestfit equation yields the value of g to be 385. Material balance equations mbal software online webinar. Material balance equation an overview sciencedirect topics. Pressure decline material balance linear plotting analysis pz vs. This value is much higher than the volumetric calculated value. However it fails completely if the flow rate is variable. The materialbalance equation for a compressive reservoir then becomes 12 eq. The conventional format of the gas material balance equation is the simple straight line plot of pz vs. Poston and berg discuss methods for adjusting pz plots for the lack of.