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Ecrin v4.20 - Doc v4.20.01 - © KAPPA 1988-2011 Topaze Guided Session #1 • TopGS01 - 7/24
B01.4 Arps analysis
Maximize the plot with a double click on its title bar, Figure B01.12.
Fig. B01.12 • Arps plot maximized
This plot is dedicated to match the production with a decline of type:  
 
q t
q
bD t
i
i
b

 1
1
Where qi is the initial rate, Di the decline factor, and b, comprised in [0, 1] determines the
decline type. Harmonic decline corresponds to a b value of 1, exponential decline to (the limit
of) the above expression for b equal to 0:  
q t q ei
D ti    .
When the plot is created, Topaze runs a non linear regression seeking the values of b, Di, and
qi that provide the best fit of the data, and the corresponding decline curve is plotted in white.
Parameters direct input
Use the Results icon of the toolbar (or a right-click in the plot) to access the dialog and
change the values directly.
This dialog is also used to specify the extent of the decline curve on the plot, and the
abandonment criterion, which will affect the results.