Page 31 - KAPPA - Ecrin v4.30 tutorials

Ecrin v4.20 - Doc v4.20.01 - © KAPPA 1988-2011 Ecrin Guided Session #1 • EcrGS01 - 29/36
When using 'Select Range', the process starts in the same manner, then any build-up with a
deduced kh leading to a derivative level outside the specified box is discarded. For the valid
build-ups, a non linear regression is run imposing a unique slope, and one intercept per period.
A plot of Skin versus Time is displayed that can be used to evaluate the change of the well
potential over time. Right click on the plot and select ‘Line - Show’ and ‘Average – Show’ to
display the straight lines. Figure E01.6 is the Semilog plot and Figure E01.7 is the plot of Skin
versus Time, after deletion of one point.
Fig. E01.6 • Semilog plots Fig. E01.7 • Skin versus Time
The skin deduced from the straight line on few Build-up are off and they can be removed from
the line calculation by clicking on them an specifying not to use them in the least square line
calculation.
E01.2 • Pressure Transient Analysis
To determine the most appropriate model, extract Build-up #2 only. In the toolbar, select
Build-up #2 from the ‘Group’ drop list. It is evident from both the derivative curve, and the
depleting pressure observed in the history plot that the reservoir is limited and bounded.
Fig. E01.8 • Loglog plot of Build-up # 2
Right click in the plot and select 'Line' and 'Delete' to hide the semilog straight line marker.
In the top tool bar, click on next to the gauge name to rename it as ‘Fltd data Backup’.
Since the pressure history was filtered using wavelets (in Diamant) we will first check that we
did not distort the shape of the derivative.