In the current atmosphere of environmental awareness, we increasingly use the phrase “zero discharge” without giving much thought to its real meaning. Even in the strictly controlled North Sea OSPAR region, only drill cuttings generated using invert-based drilling fluids are broadly regarded as “zero discharge,” and even then, the ruling that led to this conclusion still allows discharge of cuttings that have less than 1% adhering oil. This 1% oil-on-cuttings limit is now practicably attainable, and so even the North Sea can no longer be regarded as an invert fluid zero discharge area.
Discharge of water-based drilling fluids, both on cuttings and as an end of well dump, is still allowed, so long as the components of those fluids meet certain acceptance criteria such as biodegradability and toxicity limits. However, it is feared by many in the industry that the continued use of the phrase “zero discharge” may lead to the broader public and regulator expectation that the industry can truly achieve that goal.
Unfortunately, the term “zero discharge” is misleading. Whatever we do, wherever we operate, there will be discharge of some form. Zero discharge operations, as observed in the North Sea, Gulf of Mexico, and West Africa, are probably best described as discharge on land or, at best, sub-seafloor discharge. Considering the non-water quality impacts of our operations is vital to making the right choices when planning a project. Land disposal of cuttings can generate air emissions, present a risk of spills with increased transport of drilled cuttings to shore, and create long-term liabilities. How do we account for these non water-quality impacts in a way that will lead to the right choices concerning project economics, operational practicality, and the health, safety, and environmental aspects?
On Jan. 22, 2001, the US Environmental Protection Agency (EPA) published Effluent Limitations Guidelines and new source Performance Standards in the Federal Register (FR 66, No. 14. 6850-6919). EPA took a holistic approach to the issue of minimizing environmental impacts of drilling activities. Among other things, the EPA examined risk to people, land effects, air emissions, environmental justice issues, toxicity, and biodegradability of synthetic-based fluids (SBF).
The EPA study concluded that controlling the quality of SBF and controlling quantities of SBF discharged on drilled cuttings was a better alternative than shipping large quantities of drill cuttings for disposal onshore. In their initial study, EPA summarized that taking the controlled discharge route would save GoM operators $41 million per year in 1999 by simply accounting for increased efficiency offered by SBFs and by recognizing that SBF removal techniques would be improved by restricting volumes allowed to be discharged. Likewise, if zero discharge was mandated, fuel use was predicted to grow to 358,664 boe/yr compared to a decrease of 195,124 boe/yr if SBF use and discharge were encouraged. Not surprisingly, EPA calculated that the same discharge option would reduce air emissions by 3,074 tons/yr compared to the zero discharge option with an associated 5,414 tons/yr increase in air emissions.
Most in the industry feel the EPA did a good job with this analysis, but if we examine the issue closely, how does one really balance a ton of SBM cuttings discharged overboard with a ton of CO2 released to the atmosphere? Though attempted by many in our industry, a convincing, detailed environmental balance sheet comparison or cost-benefit analysis cannot be easily performed. Throw in the targets set by industry organizations, individual operators, or government agencies driven by conventions like the Kyoto protocol, and things get even more complicated.
Alternatives to the phrase “zero discharge” have been debated. A wide range of operator representatives from countries as diverse as Kazakhstan, US, Norway, UK, and Brazil have been involved. Not surprisingly, most agree that the phrase “zero discharge” is at best misleading, and at worst has the potential to seriously impact operations. After all, true zero discharge to air, land, and sea really means doing nothing at all. In contrast to the near unanimous position that the descriptor we have already is unsuitable, it is very difficult to agree on an alternative phrase: No harm to the environment?, Minimizing environmental pollution?, or Approaching zero impact? It is hardly surprising that it is impossible to reach consensus on an alternative to zero discharge that would be acceptable to all operators for offshore operations in very different parts of the world.
Solutions to pollution?
While building up a picture of your operations, and to help you make the right choice, ask yourself:
Where should we consider the boundaries to be? What is the extent of our impacts? For example, do you want to consider local air quality or global atmospheric impacts?
What does zero discharge really mean where I operate? Different interpretations are given by numerous regulators, operators, and even at the individual project level
What are my real impacts? Consider air, water, and land impacts, resource use, effects on local communities, and future liabilities
What are the fluid alternatives available? The use and discharge of some high performance water-based muds may be especially applicable where invert cuttings cannot be discharged.
John Hall
Senior Environmental Specialist
Halliburton Baroid
