Non-stick properties test

The process of salt depositing on internal parts of downhole equipment – scaling – is determined by many factors, including the sticking (or adhesive) properties of the equipment material. 

We will consider wettability as a particular case of adhesion. Contact angle – the angle between solid and liquid surface. This measurement will provide us more quantitative approach to estimate sticking capability.

Since formation fluid is a conductive material, we will study the effect of voltage supply on pump stage materials (Ni-resist and polymer) sticking properties.

Testing equipment

Testing bench, power unit, photo camera.

Testing substance

Distilled water (dielectric) and normal saline (conductive fluid)

Testing samples                      

Ni-resist/ni-resist friction couple     

 Ni-resist/polymer friction couple

  Testing procedure

1.       We dried clean both friction couples

2.       Isolated parts of the friction couple from each other with a tape and silicon sealer

3.       Placed the friction couple on the testing bench and connected to the power adapter

4.       Injected a drop of testing substance (at first - water, after that NS) on the friction couple so that the drop was right between the friction parts

5.       Then we were applying voltage on the testing sample from 0 to 1V with the step of 0.2V and duration of 5 sec.

6.       We made photo on every stage of the voltage change

7.       Measured the contact angle

Test results

Change of contact angle for Ni-resist/ni-resist couple 

 Change of contact angle for Ni-resist/polymer couple

 Conclusion

1.       The contact angle of water drop for both testing samples did not change since the distilled water is a non-conductive liquid.

2.        The contact angle of NS drop for ni-resist/ni-resist couple decreased by 23% as we increased voltage from 0 to 1V. That raises the risk of scaling.

3.       The contact angle of NS drop for ni-resist/polymer couple did not change as we increased voltage from 0 to 1V. That means no scaling and stable operation even after mineral deposition.