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Drilling fluids QA/QC - Quality Control of Barites

The following tests shall be carried out, or fully supervised, by the Mud Engineer, to determine the quality of barites delivered to the rig.

Sampling

Barites shall be sampled using the same method as outlined for cement above.

Testing

Contamination of barites by bentonite is determined simply by the fact that severe gellation will occur when the sample is mixed with distilled water.

After drilling 16in/17.1/2in hole the bulks are to be very clean from bentonite before receiving any barite. The following section outlines the two chemical methods are outlined below for detection of cement contamination of barites. Before carrying out the tests, all equipment used must be cleaned and rinsed with distilled water.

pH, Ca Test

1. Take 100 g of Barites and MIX with 100 ml of distilled water in a stoppered Erlenmeyer flask for 15 minutes

2. Filter the mixture through the API filter press.

3. Measure pH of filtrate.

4. Take 10 ml of the filtrate and determine calcium content by Versenate titration. Calcium (ppm) 40 x ml Versenate solution.

Note: pH should be lower than 10.5. Calcium content should be lower than 150 ppm.

Sugar Test

1. Put7.4 g of barites, 15 g of granulated sugar and 100 mls of distilled water into a 125 mls Erlenmeyer flask and ATTACH stopper.

2. Shake for 15 minutes (flask must stay stoppered to prevent reaction with C02 from air).

3. Filter through API filter press and retain all filtrate.

4. Add 3 drops of Phenolphthalein solution and titrate with 0.1 N H2 S04, till pink colour has disappeared.

5. Calculate estimated amount of cement *

%cement  0.1 x mls. 0.1 N H2 SO4.

Note:   %cement should be less 0.5%.

Calculation based on estimated Ca(OH)2 content of cement of 50%.

Detection of Contaminated Barites

In the event that contamination of the barites is detected the Mud Engineer/Drilling Supervisor shall ensure:

rejected material is not transferred.

  • samples are sent to the Mud and Cement Laboratory stating
  • date
  • rig
  • supply vessel/truck
  • sample type / dispatched method
  • type of contamination
  • any other relevant information
  • written report from Mud Engineer and Drilling Supervisor to Head of Drilling Operations.