A field procedure for determining graphite in drilling mud is presented which is sensitive to 0.25 lbs/bbl and accurate to 20 per cent. The method, utilizing oil flotation principles, is suitable for use in all oil-free water base muds except those containing ligno-sulfonates, lignites, or surface active agents.
Instructions for determining graphite in mud:
- Collect representative one gallon sample from mud stream.
- Clean and rinse well with water four 250 ml volumetric flasks labeled I, II, III, and IV.
- Measure 100 ml fresh or distilled water to each flask and swirl gently to disperse mud. Add exactly 5 ml toluene to each flask.
- Examine oil layers in the necks of the flasks. A layer will grade from clear toluene at top to a darkened emulsion at the bottom, the volume and darkness of the emulsion depending upon the amount of graphite in the flask.
- Clean mixing cans and flasks. Re-stir gallon sample taken in step 1.
- Proceed exactly as in steps 2, 3, and 4, except instead of using the table in step 4, use the following table to find graphite concentration of mud.
