Difference between revisions of "P/Z plot"

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[[P/Z plot]] is a part of the [[Reservoir Management]] workflow of the [[:Category:E&P Portal | E&P Portal]].
 
[[P/Z plot]] is a part of the [[Reservoir Management]] workflow of the [[:Category:E&P Portal | E&P Portal]].
 +
 +
[[Flowing Material Balance]] is the advanced tool to determine well's and reservoirs GIIP and well's JD.
  
 
== Nomenclature  ==
 
== Nomenclature  ==
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:<math> V_r </math> = reservoir volume (constant), ft<sup>3</sup>
 
:<math> V_r </math> = reservoir volume (constant), ft<sup>3</sup>
 
:<math> z </math> = gas compressibility factor (changing), dimensionless
 
:<math> z </math> = gas compressibility factor (changing), dimensionless
 
== References ==
 
<references>
 
 
<ref name= Griffith>{{cite journal
 
|last1= Griffith |first1=P.
 
|last2= Wallis |first2=G. B.
 
|title=Two-Phase Slug Flow
 
|journal=Journal of Heat Transfer
 
|publisher = ASME
 
|date=August 1961
 
|volume=83
 
|pages=307-320
 
|url=http://heattransfer.asmedigitalcollection.asme.org/article.aspx?articleid=1432339&resultClick=3
 
|url-access= subscription
 
}}</ref>
 
 
<ref name= Orkiszewski>{{cite journal
 
|last1= Orkiszewski |first1=J.
 
|title=Predicting Two-Phase Pressure Drops in Vertical Pipe
 
|journal=Journal of Petroleum Technology
 
|publisher = SPE
 
|number = SPE-1546-PA
 
|date=June 1967
 
|volume=19
 
|url=https://www.onepetro.org/journal-paper/SPE-1546-PA
 
|url-access= subscription
 
}}</ref>
 
 
<ref name=Economides>{{cite book
 
|last1= Economides |first1=M.J.
 
|last2= Hill |first2=A.D.
 
|last3= Economides |first3=C.E.
 
|last4= Zhu |first4=D.
 
|title=Petroleum Production Systems
 
|edition=2
 
|date=2013
 
|publisher=Prentice Hall
 
|place=Westford, Massachusetts
 
|isbn=978-0-13-703158-0
 
}}</ref>
 
</references>
 
  
 
[[Category:E&P Portal]]
 
[[Category:E&P Portal]]

Revision as of 11:03, 21 November 2017

Brief

The P/Z plot is a plot of P/z versus cumulative gas production, Gp.

The interpretation technique is fitting the data points with the straight line to estimate GIIP.

The P/Z plot is based on the Gas Material Balance equation.

Math & Physics

Applying Real Gas EOS at reservoir conditions:

 PV_r=z\frac{m}{M} RT_r (1)

Applying Real Gas EOS at standard conditions:

 P_{SC}V_g=1\frac{m}{M} RT_{SC} (2)

Dividing eq. 2 by eq. 1 and rearranging:

 V_g=\frac{P}{z} \frac{V_rT_{SC}}{P_{SC}T_{r}} (3)

Applying eq. 3 for initial conditions and for any point in time:

 GIIP=\frac{P_i}{z_i} \frac{V_rT_{SC}}{P_{SC}T_{r}}

Applying eq. 3 for any point in time:

 GIIP-G_p=\frac{P}{z} \frac{V_rT_{SC}}{P_{SC}T_{r}}

Therefore at any time:

 \frac{G_p}{GIIP}=1-\frac{P}{z} \frac{z_i}{P_i}

Or:

 \frac{P}{z}=\frac{P_i}{z_i} \left (1- \frac{G_p}{GIIP}\right )

Thus a plot of P/z vs cumulative produced gas is a straight line intersecting X axis at GIIP.

Discussion

P/Z plot is a part of the Reservoir Management workflow of the E&P Portal.

Flowing Material Balance is the advanced tool to determine well's and reservoirs GIIP and well's JD.

Nomenclature

 GIIP = gas initially in place, ft3
 P = reservoir pressure (changing), psia
 P_{i} = initial reservoir pressure (constant), psia
 P_{SC} = pressure at standard conditions, psia
 T_i = initial reservoir pressure (constant), °R
 T_r = reservoir pressure (constant), °R
 T_{SC} = temperature at standard conditions (constant), °R
 V_g = volume of gas in reservoir converted to standard conditions (changing), ft3
 V_r = reservoir volume (constant), ft3
 z = gas compressibility factor (changing), dimensionless