Test to determine nature and source of alkalinity in the mud and give an indication of mud condition. Correct interpretation of the results will highlight Carbonate / Bicarbonate contamination of mud which can lead to increased gel strength and YP.
One sample of filtrate is used for determination of Pf and Mf; the Mf is measured after the Pf has been determined.
A pH meter can also be used for this test instead of indicators, in which case, the Pf / Pm end point should be determined at pH 8.3, and the Mf end point at pH 4.3.
Reporting
|
Parameter |
Unit |
Accuracy |
|
Pf |
mls |
± 0.1 |
|
Mf |
mls |
± 0.1 |
|
Pm |
mls |
± 0.1 |
Sources of Error
It is sometimes difficult to see the Methyl Orange end point. For this reason some mud engineers prefer to use Bromo Cresol Green indicator. The procedure is the same in both cases.
Since the Pm titration is carried out using whole mud, it can be difficult to see the end point, especially when using dark coloured muds, such as those treated with Lignosulphonate. More accuracy may be achieved by using a pH meter in this case. In the CFL treated mud filtrate it can be difficult to see indicator changes. Revert to use of pH meter.
Testing of this type has little value in mud systems treated with certain buffers. If in doubt consult the Operations Engineer.