Page 264 - KAPPA - Ecrin v4.30 tutorials

Ecrin v4.20 - Doc v4.20.01 - © KAPPA 1988-2011 Topaze Guided Session #1 • TopGS01 - 18/24
With an exponential decline, a linearity is seen and its intercept with the X-axis gives the initial
fluid volume in place.
In gas, the variation of the PVT properties cannot be disregarded and this variation requires a
prior estimate of the gas in place, and therefore an iterative solution. The plot displays:
) ( ) (
w i pm pm
q
 versus
 
 
) ( ) (
)( ) ( .
w i
i i
DA pm pm
pm pmG
Q



The value of 'X' at the intercept is Gi.
On the Normalized rate cumulative plot a line can be created, either by regression or drawn.
This line may then be modified interactively. Right click in the plot when maximized to access
the Line option.
Fig. C01.9 • Normalized rate cumulative plot results
Blasingame type curve plot
This plot displays a dimensionless representation of the Blasingame plot. The objective is to
compare the rate-pressure data put in dimensionless format with a set of type curves
illustrating the transient solution for a vertical well in a circular reservoir for a series of Re/rwa
values, where Re is the reservoir size and rwa the equivalent wellbore radius. The right-hand
side part of the type curves corresponds to boundary-dominated flow. Matching the data on
the Blasingame type curve plot provides estimates of the reservoir size, the permeability, and
the equivalent wellbore radius – hence the well skin.
p-q plot
This plot displays a simple cross plot of pwf vs. q. On this plot, infinite acting radial flow is
diagnosed as a negative slope section while pseudo steady state should exhibit a positive line.
Furthermore, the slope of the PSS section is inversely proportional to the volume drained. This
plot may thus be used as a diagnostic tool to detect compartments.