Basic HTML Version
OH – ET – VA - LL: Analysis of Dynamic Data in Shale Gas Reservoirs – Part 1 – Version 2 (December 2010)
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4 – Late time straight line material balance plot
This classical analysis is already implemented in Topaze in the normalized rate cumulative
plot; it relies on a material balance calculation. For boundary dominated flow, dimensionless
rates and cumulative productions are linked by:
A plot of q
D
versus Q
DA
exhibits a straight line when boundary dominated flow is established,
and an estimate of the pore volume can be obtained from this slope. Here again the question
that we have to address is whether this analysis technique can be applied to the interpretation
of shale gas wells – in other words: can we see any actual boundary dominated flow and what
is the physical meaning of the parameters derived from this technique?
5 – KAPPA’s analytical models for fractured horizontal wells
KAPPA has written and published two semi-analytical solutions that can simulate the transient
flow behaviour of multi-fractured horizontal wells. The current solutions were developed by Leif
Larsen (KAPPA) under the following assumptions:
The well drain is strictly horizontal, the vertical or slanted section is not perforated;
the horizontal drain crosses the vertical fractures perpendicularly;
the distance between the fractures can be variable;
the reservoir can either be homogeneous or heterogeneous (double-porosity);
the fracture model can either be infinite conductivity, uniform flux or finite conductivity;
each fracture can be individually described by its height, its length, skin and conductivity;
the gas flows into the fractures only, the well drain only or both simultaneously.
Fractured analytical horizontal well model:
Saphir log-log plot showing the sensitivity to the fractures ½ length