Chemical Pollution and Discharge of Drilling Fluids

The use of chemicals is “critical for the production of oil and gas” and part of many routine exploration activities. Impacts in the marine environment include “acute or long term toxic effect to marine organisms” and it “can result in hormonal, mutagenic and reprotoxic effects that can impact whole populations of species and result in high exposure for top predators like seabirds and marine mammals.”

One of the main sources of chemical pollution in oil development is the discharge of drilling fluids into the marine environment along with drill cuttings. BP’s plan included use of both Synthetic Based Mud (SBM) and Water Based Mud (WBM) drilling fluids. The plans ensure that SBM represents no more than 6.9% by weight on cuttings discharged overboard, and only discharge WBM overboard in bulk. With these measures in place, its Environment Plan Summary lists the risk from drilling fluid discharge as being of “minor significance.”

However once again, this fails to take into account the conservation values of the Great Australian Bight marine environment, and does not comply with global standards. In the Oslo/Paris Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) Commission region, for example, “cuttings contaminated with synthetic fluids can only be discharged in exceptional and very rare circumstances”. Similarly, while it is true that water based drilling fluids have less impact than oil based fluids, they still contain chemicals and according to the OSPAR Commission “the discharge of water based fluids and associated drill cuttings are still a concern in areas with sensitive benthic fauna.” As outlined above, the benthic ecological communities in the Bight are sensitive and have high levels of endemism.

Without further study, and identification of exact drilling locations, any discharge from SBM and bulk discharge of WBM should therefore be considered a high-risk activity.

Minor Oil and Chemical Spills

Although much public attention is rightly focused on the threat of a catastrophic oil spill, it is important to note that minor spills of oil, chemicals, and other hazardous materials pose a cumulative risk to the marine environment. These incidents occur frequently and are caused by a range of factors, from human error to equipment failure. In the OSPAR Commission region, for example, there was an annual average of 637 oil spills of one tonne or less between the year 2000 and 2007.