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16
Sample Data
Graph 1
Graph No. 1 displays the bentonite - fluid interaction for the fluid during
the entire 18.3 hours period for the test and very precisely shows the trend
between the four fluids.
All of the base fluids show a positive slope which confirms an immediate and
constant interaction between the clay and the base fluid.
The black curve of fresh water had the highest expansion rate - more than
doubling its axial dimension.
The red curve of glycol showed the highest rate of shale stabilization over
most of the test period. As seen in this graph, stabilization began around 275
minutes into the test with a maximum expansion of 46%. The glycol acted as
the better shale stabilizer exceeding all other fluids. The amount of expansion
stayed in a straight line of zero slope indicating a very positive balanced
activity resulting in an ideal condition for wellbore stability.
The yellow curve of Potassium Acetate stabilized around 350 minutes into
the test with a 58% expansion. This fluid also exhibits some shale stability
although not quite as good as the glycol-based fluid.
The black curve of fresh water and the blue curve of the g surfactant
fluids showed very clearly that these fluids do not contribute to the stability of
this shale sample.
The blue g surfactant base initially acted as an adequate shale
inhibitor, however after 330 minutes it was surpassed by the Glycol and after
500 minutes by the Potassium Acetate base fluid. While performing better
than fresh water, its positive slope throughout the test showed a limited
capacity as an effective shale stabilizer.
