11
Specialized plots
Additional specialized analysis plots can be created
with options tailored to specific flow regimes.
These include very short-term tests or FasTest
TM
for
perforation inflow testing and predefined types such
as MDH, Horner, square root and tandem root.
Analytical models
Saphir offers a built-in analytical catalog combining
well, reservoir and boundary models. External models
(
see pages 50–51) can be downloaded. Interactive
‘
pick options’ are offered for most parameters for
a first estimate by selecting a characteristic feature
of the model on the Bourdet derivative. There is
an option to use the AI package ‘KIWI’ as a guide.
Additional capabilities include rate dependent skin,
changing wellbore storage, interference from other
wells, gas material balance correction, well model
changing in time, horizontal and vertical anisotropy.
Numerical models
As the case complexity increases, numerical models
are used for geometries beyond the scope of
analytical models. These are predominantly 2D but
with 3D refinement where needed. This includes the
fractured horizontal well model for unconventional
resources.
These numerical models also address nonlinearity.
Pseudopressures are replaced by the exact diffusion
equations for real gas, non-Darcy flow, pressure
related physical properties, multiphase flow, water
and gas injectors, water drives, and more recently
desorption models for shale gas and CBM.
Classical Horner plot
2-
Porosity PSS - Picking the transition
Interpretation using a numerical model
