Under the European Union’s most recent conventions and regulations, produced water discharged into the sea must be shown to have no significant toxicity. TotalEnergies has been preparing to meet that standard for many years, and already boasts the requisite technology and methods. Moreover, every TotalEnergies affiliate worldwide must now meet that same requirement, in line with our commitments as a responsible operator.
A Mandate that Applies to Every Exploration-Production Affiliate
The Convention for the Protection of the Marine Environment of the North-East Atlantic, or OSPAR Convention, will take full effect at the end of 2018*. From that point on, Total will have to do more than simply keep the hydrocarbon content in produced water discharges below 30 milligrams per liter. We’ll also have to assess and manage the risk to the environment posed by the potentially toxic compounds found in that aqueous effluent. The challenge will be to reduce the risk of those discharges having a harmful impact on marine ecosystems.
That represents a quantum step forward in our strategy of continuously improving the quality of our produced water, and has naturally been a top priority. The work we’ve undertaken in recent years has brought that goal within reach: we now have a methodology for managing our aqueous effluent that is consistent with the risk-based approach promoted by the OSPAR Convention.
That methodology — now incorporated into E&P’s HSE guidance — is designed for use by all our affiliates in the Northeast Atlantic region and beyond, including those for which it isn’t mandated. Wide-scale adoption of that best practice is simply part of TotalEnergies’ commitment to comply with the most stringent environmental standards everywhere it operates.
A Strategy Based on Environmental Risk Assessment
Current regulations map out a precise methodology for assessing the risk that produced water poses to the marine environment. The first step involves preparing a detailed list of the compounds dissolved in that water — which may include substances that are naturally present in the reservoir or chemicals that were added during production or processing — and determining their concentrations in the effluent.
Step two is to identify the extent to which marine organisms are being exposed to the substances contained in the discharge. For that, TotalEnergies uses DREAM (Dose-related Risk and Effect Assessment Model), purpose-designed software developed through a Joint Industry Project with independent Norwegian research organization SINTEF. DREAM produces a hydrodynamic model of the discharge plume in a marine environment. That model can then be used to estimate the concentration of each compound and calculate how that amount will evolve over time and space within the marine environment, particularly as a result of physical phenomena such as turbulence, dissolution and evaporation.
The environmental risk is ultimately determined by comparing that level of exposure to the intrinsic toxicity of the products found in the effluent, as calculated by ecotoxicological testing conducted in the laboratory. That risk must comply with statutory limits in order to pass muster.
An Ongoing Quest For Improved Performance
To reduce the ecotoxicity of our produced water discharges, it is essential that we use chemicals responsibly and optimize our water treatment process. Our efforts to find innovative solutions all focus on continuously reducing the harmful impact of those chemicals.
The chemicals used in our production processes, which may persist as trace pollutants in produced water, need to have the lowest possible ecotoxicity. That’s why environmental performance — measured by toxicity, biodegradability and bioaccumulation potential — is just as important a criterion as efficacy and cost when we select chemicals.
Our R&D is focusing in particular on the type of chemical additives used as corrosion inhibitors, which are the primary source of potential toxicity in wastewater. Among other things, we’re helping to devise new chemical formulations designed to make those biocides more biodegradable. At the same time, we’re developing an innovative biomonitoring tool for microbial corrosion. Using miniaturized technology borrowed from molecular biology, the tool can be deployed at each site to monitor microbial activity much more accurately and frequently. This will produce corrosion treatments that are better tailored to our needs and prevent the risk of excess chemical use.
Extracting chemicals from aqueous effluent poses a particular challenge at offshore sites. The biological treatments available for that purpose are too cumbersome to be installed on our platforms. But we’re on the verge of overcoming that problem, thanks to a new technology known as a moving bed biofilm reactor (MBBR). It’s a form of enhanced biotreatment for eliminating dissolved matter in produced water, and it delivered an excellent performance record during an eight-month test run that was completed in the spring of 2017. In addition to being more economical than the biological treatments currently on the market, an MBBR allows for much faster water purification and requires significantly less space. This added resource for new offshore development projects is a tangible demonstration of our ability to reduce the environmental footprint of our operations.
Place the Environment at the Center of our Strategy
DIESTA: Optimizing Efficiency During LNG Liquefaction
BIOMEM: a Compact Biological Process to Treat Produced Water