KAPPA DDA Book v5.12

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Dynamic Data Analysis – v5.12.01 - © KAPPA 1988-2017 Chapte p102/743
3.F Test design
Pressure Transient Analysis is performed on data that were acquired during dedicated
operations (well tests) or from permanent gauges. In order to optimize a coming well test, one
can use the modelling capabilities of the PTA software to run a test design, i.e. simulate the
response of a well test from the parameters or range of parameters we expect. It is then
possible to play with the different scenarios and adapt them to the various constraints and the
test objectives.
In order to run the scenarios the engineer must rely on known information and data or make
reasonable assumptions. To explore ‘what-if’ scenarios, sensitivity studies are carried out and
based upon these the engineer can choose both downhole and surface equipment including,
amongst others, pressure gauges with adequate accuracy and resolution. Surface equipment
must be selected which includes facilities to measure the flowrate of gas, oil and water. This
done, the engineer can make the safest and most economical plan to reach the test objectives.
3.F.1 Safety
Safety is the primary concern in all well testing operations and is the mandatory objective that
must be met before any other. With the safety constraints applied the objectives of the test
must be defined, operational limitations identified and scenarios considered that clearly show if
the objectives will be met and if not, why not. The safety aspects of well testing are covered in
a variety of documents and books available on the internet and elsewhere. All companies have
their own procedures and standards and they should all be fairly common as they have to
conform to rules and regulations set down by the various regulatory bodies overseeing
different parts of the world. This section is just to remind the reader that Hazard and
Operational studies (HAZOPS) for well test operations exist and they must always be applied to
ensure safe practice and operation.
3.F.2 Objectives
It sounds obvious but you must know what you want to achieve. What are the ultimate results
you would like to obtain from the considerable investment involved in running such a test, and
what are the results going to be used for. An assessment of the value of the results is also
necessary to avoid ‘overkill’ and unnecessary expenditures. Below is a non-exhaustive list of
parameters one may want to determine in a well test:
 Well model (fractures, partial penetration, slanted and horizontal well parameters)
 Reservoir model (double porosity, layer and composite parameters)
 Boundary model (distance and type of boundaries)
 Permeability
 Skin
 Heterogeneities (double-porosity, layer and composite parameters)
 Static pressure
 Layer parameters (properties and pressure)
 Layer contributions