Retort (Oil/Water/Solids)

Purpose

Quantify the oil, water, and total-solids content of a drilling fluid by vaporising the liquid phases and collecting them as condensate. Results are used to calculate low-gravity and high-gravity solids, oil:water ratio, and retort water salinity correction.

Equipment

• Retort still (10 mL or 20 mL cup capacity)
• Calibrated heating unit
• Graduated collector tube (10 mL or 25 mL)
• Ice bath or cooling coil
• Thermometer
• Spatula and sample cup

Procedure

1. Clean and dry the retort cup, body, and condenser coil.
2. Fill the retort cup to the brim with a well-mixed mud sample using the cup’s exact volume.
3. Add a small amount of steel wool to the cup to aid vaporisation and prevent bumping, if specified.
4. Assemble the retort; ensure the condenser outlet feeds into the graduated collector tube. Surround the condenser in ice to maximise condensate recovery.
5. Apply heat at the manufacturer’s recommended setting and allow the retort to run until no further liquid collects (typically 45–60 minutes).
6. Read the total liquid volume: note the upper (oil) and lower (water) layers in the collector tube.
7. Record oil volume (% oil = oil mL / cup mL × 100) and water volume (% water = water mL / cup mL × 100).
8. Calculate total solids: % solids = 100 − % oil − % water.

Notes

• For accurate oil/water separation in the collector, allow the condensate to stand until layers are distinct.
• Correct the water volume for dissolved salts if the filtrate chloride content is known.
• Report oil %, water %, and total solids % by volume. Distinguish high-gravity (barite) and low-gravity solids using mud weight and retort data.
• Keep heating element and condenser connections clean and leak-free to prevent loss of vapour.