Preparing cuttings samples drilled with invert mud

Invert (oil based) mud poses very specific challenges when it comes to cleaning drill cuttings. Invert mud coats the cuttings in a sticky membrane; in order to eliminate this, the coating has to be dissolved with thinners and shaken off using kinetic energy. Most cleaning methods are time consuming and require large quantities of water and cleaning agents. Examples of methods include usage of blenders, shakers or jars, dedicated systems such as the MOLE. Blenders are labour intensive and can deform the cuttings. Automated sample washers use large quantities of water and the end product is not always clean.

Pressure nozzle Pressure nozzle, hose and adaptors

Our recommended method relies on a simple pressure nozzle of the lawn spray or car washing variety.


Chemicals used range from industrial grade thinners such as Varsol, to natural solvents such as Ultimate 5000, or can be as arcane as dish soap. We do not recommend using poisonous or corrosive chemicals, and recommend the use of natural cleaners or household detergents such as Sunlight or commercial degreaser such as Protocol K-300i or mild synthetic solvent such as Synthesol.

Protective equipment
  • Goggles must be worn at all times to prevent chemicals or invert from being sprayed in the eyes.
  • A coverall or apron should be worn to protect clothing.
  • Non-latex gloves must be worn when washing the samples. Medium strength or heavy duty rubber gloves are recommended.
  • A respirator mask is recommended to protect from steam and invert fumes. Reusable models with replaceable cartridges (ex: 3M 5000 model) are preferred.
  • The work area must be properly ventilated.
  • Washer machine hose with faucet adaptor.
  • Lawn spray nozzle, jet only type (such as an adjustable nozzle)
  • 4” 80 mesh sieve (brass or plastic)
  • 4” 40 or 30 mesh sieve
  • Shop vac (wet/dry) with 4″ adaptor cup

The setup:

Unscrew pressure regulator from faucet. Connect a short hose (such as a washer machine hose) to the sink faucet using a crossover. Connect a variable discharge pressure nozzle (gardening use) to the hose. Turn on the hot water. Turn the nozzle to produce a straith jet, tweak the discharge dial to adjust pressure of jet.

Cleaning process
  1. Instruct sample catcher to rinse cuttings in base oil, this may eliminate the dirtier part of the invert mud.
  2. Empty sample bag in 40 mesh sieve, with the 80 mesh sieve placed underneath. Add some Sunlight soap. Jet-spray the sample and soap through the 40 mesh into the 80 mesh sieve.
  3. Dispose of what’s left in the 40 mesh sieve (most likely cavings). Add more soap to the cuttings in the 80 mesh sieve. Wash sample (stirring it with the hot water jet) until foam clears. Repeat until foam is white (clean). Depending on how dirty the invert mud is, it may require 2 to 5 wash/rinse cycles. Heavier invert is generally harder to wash and requires more cycles.
  4. Place sieve in shop vac adaptor cup and dry.

We found that this method produces clean samples with minimal effort and does not waste unreasonable amounts of water.

Calin Dragoie

Posted On:
September 5, 2010

Technical Articles, Uncategorized