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Dynamic Data Analysis – v5.12.01 - © KAPPA 1988-2017
Chapter
3 – P ressure Transient Analysis (PTA)- p58/743
The main flow regime of interest is the Infinite Acting Radial Flow, or IARF, which occurs after
well effects have faded and before boundaries are detected. IARF may not always be seen.
IARF provides an average reservoir permeability around the well, the well productivity (skin).
When the well is shut in we also get an estimate of the reservoir static pressure (p* or pi). The
first PTA methods were specialized plots (MDH, Horner) introduced in the 1950’s to identify
and quantify IARF. Other specialized plots dedicated to other flow regimes followed through.
Fig. 3.A.3 – MDH plot
Fig. 3.A.4 – Horner plot
In the 1970’s loglog type-curve matching techniques were developed to complement straight
lines. One would plot the pressure response on a loglog scale on tracing paper and slide it over
pre-printed type-curves until a match is obtained. The choice of the type-curve and the
relative position of the data (the match point) provided physical results. These methods were
of poor resolution until the Bourdet derivative was introduced.
Fig. 3.A.5 – Manual Drawdown
type curve matching
Fig. 3.A.6 – Drawdown Type Curve
In 1983, the Bourdet derivative, i.e. the slope of the semilog plot displayed on the loglog plot,
increased the resolution and reliability of a new generation of type-curves.
Fig. 3.A.7 – Superposition plot
Fig. 3.A.8 – Derivative plot