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Ecrin v4.30 - Doc v4.30.01 - © KAPPA 1988-2013 Saphir Guided Session #9 • SapGS09 - 1/21
Saphir Guided Session #9
A01 • Introduction
When horizontal wells were introduced some 30 years ago the well test analyst suddenly had a
problem; there was no analytical model available. This was quickly remedied and a simple
horizontal analytical well model was introduced, however it was strictly horizontal and was not
able to cut through different horizons. This meant that the actual layers were also strictly
horizontal. The reservoir was homogeneous, double porosity, or composite and could be
bounded by a circle, rectangle or any shape using the 2D Map (analytical or numerical). The
well could not extend from one zone to another, and subsequently the first equivalent
numerical wells followed the stratigraphy of the zone where the well started.
An analytical multilayered slanted well was later introduced, however the layers were still
strictly horizontal. This model is described in the DDA book chapter 6 (6.I.5).
It was evident that a model which could realistically represent a true horizontal well cutting
through different facies and zones would be necessary to develop.
B01 • How to build a wiggly well model in Saphir
In order to follow the guided session with ease it is expected that all the other guided sessions
in the repertoire have been completed. The guided sessions are found under the menu ‘Help -
Tutorial’ in the applications Saphir, Topaze and Rubis.
There are two main approaches when building the wiggly, or in this instance a slanted or an
undulating horizontal well. The wells can be placed in strictly horizontal multi or single layers in
Saphir and Topaze. They can be slanted or placed horizontal in one layer. If the linear
numerical model is used, then the application will only generate the single phase solution using
the declared main phase, and there will be no cross flow between layers. In order to impose
cross flow it is necessary to use the non-linear option. In Rubis a horizontal or undulating well
can cut through any horizon layer, horizontal or not, and can even cut through the same
horizon several times. Cross flow between layers can be imposed even if a single phase has
been declared.
The wiggly well can only be generated with the nonlinear and linear numerical model; however
it is interesting to compare the final results with the analytical models which would represent
the numerical configuration closest.
There is no difference in building a wiggly well model in Topaze and Saphir and the main
difference in building the model in Rubis is the characteristics of the geometry of the reservoir.