Environmental Chemistry Division - Case Studies...


Biodegradation of Base Fluid

As the environmental impact of offshore drilling becomes increasingly important, exploration companies are starting to use synthetic base fluids that, when discharged, may have an impact on marine eco-systems. These base fluids reside in cuttings piles on the seabed below the platform or mobile rig. As these piles are largely oxygen starved, it is important to be able to determine the rate of anaerobic biodegradation of these base fluids in conditions that are similar to those found in the off-shore environment. Anaerobic biodegradation is an important factor for reducing the impact of multi-well platforms that create a larger cuttings pile.

In a recent investigation for an overseas client, the anaerobic biodegradation of three base fluids were tested. A closed bottle anaerobic biodegradation protocol was developed to monitor the biodegradation products associated with anaerobic biodegradation. Initially ISO 11734 was used as a reference for the project, however, various modifications were incorporated into the protocol to ensure more robust, comparative results.

Oil Mist Monitoring
A recent project on the North West Shelf of Australia was undertaken to investigate the exposure of staff to synthetic based muds (SBM) in a mud handling area of an offshore oil rig. Much of the equipment in this area, eg. shakers, centrifuges etc, has the potential to produce airborne hydrocarbons in the form of oil mist/vapour.

Appropriate sampling points were chosen to represent a cross section of the environment encountered by personnel working in these rooms. Background levels were determined when the pits contained the SBM, but before drilling started. Sets of samples were taken over 24 hours while drilling. Air temperature, humidity and mud temperatures were recorded during sampling time.

The analysis was performed using the current international standard methods which involved specialised sampling equipment for simultaneous collection of oil mist and vapour (NIOSH 5026, ASTM D3687). Vapour samples were actively collected on carbon tubes and passively collected on carbon “Radiello” tubes in accordance with methods detailed on the Radiello website: http://www.radiello.com/english/index_en.html