The offshore de-oiling process is a vital part of current oil recovery, as it separates the profitable oil from water and ensures that the discharged water contains as little of the polluting oil as possible. With the passage of time, there is an increase in the water fraction in reservoirs that adds to the strain put on these facilities, and thus larger quantities of oil are being discharged into the oceans, which has in many studies been linked to negative effects on marine life. In many cases, such installations are controlled using non-cooperative single objective controllers which are inefficient in handling fluctuating inflows or complicated operating conditions. This work introduces a model-based robust H ∞ control solution that handles the entire de-oiling system and improves the system’s robustness towards fluctuating flow thereby improving the oil recovery and reducing the environmental impacts of the discharge. The robust H ∞ control solution was compared to a benchmark Proportional-Integral-Derivative (PID) control solution and evaluated through simulation and experiments performed on a pilot plant. This study found that the robust H ∞ control solution greatly improved the performance of the de-oiling process.
The idea for this project originated within the Arctic Council’s Protection of the Arctic Marine Environment (PAME) Working Group, where a concern was raised about the disposal of tailings from onshore mining operations onto the seafloor. This led to a broader reflection on the impacts of mining operations on the marine environment. Many Arctic governments support the development of a mineral extraction industry, provided it operates in an environmentally responsible manner and considers socio-economic impacts to local communities. However, the environmental impact of existing and future mining operations is often debated. This report summarizes the results of the multi-year Existing Waste Management Practices and Pollution Control for Marine and Coastal Mining project, developed under the auspices of the Protection of the Arctic Marine Environment (PAME) Working Group.
Aarhus University, DCE - Danish Centre for Environment and Energy, has prepared an overall assessment of the potential environmental impacts from a major release or spill of ammonia in relation to production and transportation of ammonia in a PtX plant or by shipping in Greenland. Three sites were included in the assessment: Kangerlussuaq (Sdr. Strømfjord), Kangerlussuatsiaq (Evighedsfjorden) and Nuup Kangerlua (Godthåbsfjorden). The overall findings shows that a large, worst-case ammonia spill could cause severe toxic damage to organisms during the passage of the ammonia cloud from within a few km to possibly more than 10 km from the source. This could lead to local loss of animal and plant abundance for some years. However, the ammonia will be quickly diluted and degraded and will not be transferred in the food web, and the mortality will not seriously impact plant and animal populations at a regional scale. There could be a fertilising effect of ammonia on the nutrient-poor terrestrial environment lasting for some years.
The current and potential use of the seas and oceans is often called the 'Blue Economy'. Recently, the European Commission launched its Blue Growth Strategy on the opportunities for marine and maritime sustainable growth. The European Commission considers that Blue Growth is a long-term strategy in the marine and maritime sectors with great potential for innovation and economic growth. Holistic spatial planning systems supporting sustainable development have proven themselves in terrestrial planning and are also needed at sea. Due to this reason,
the BONUS BASMATI project is based on the ecosystem services approach to assist in assessing sustainable solutions corresponding to policy goals.
Determination of the causes of mortality in stranded marine mammals can contribute valuable information for conservation of wild populations, as well as contribute to risk assessments for different pathogens, hosts, and environmental conditions. This study examined necropsy reports for harbor (Phoca vitulina; n = 213) and gray (Halichoerus grypus; n = 40) seals stranded in Denmark in the period 2014 to 2021 to determine the causes of mortality where feasible. The likelihood that human interactions did or might have contributed to the mortality was also assessed. Infection with lungworms, heartworms, gastrointestinal roundworms, and influenza virus was tested for each seal in the data. Parasitic bronchopneumonia was the most common cause of death in both harbor (n = 68) and gray (n = 8) seals, and significantly more juveniles than adults died as a result of parasitic infections in the harbor seal cohort. Starvation was also a major cause of death in juvenile seals. Cause of death, death class (found dead, euthanized, or culled), and whether human interactions played a role in mortality did not vary significantly between the two species. Traumatic causes of death, resulting from confirmed or probable human interactions, were associated with adult and subadult seals of both species. Culling was the cause of death for 13.6% of harbor seals and 17.5% of gray seals.
Offshore de-oiling installations are facing an increasing challenge with regards to removing oil residuals from produced water prior to discharge into the ocean. The de-oiling of produced water is initially achieved in the primary separation processes using gravity-based multi-phase separators, which can effectively handle large amounts of oil-well fluids but may struggle with the efficient separation of small dispersed oil particles. Thereby hydrocyclone systems are commonly employed in the downstream Produced Water Treatment (PWT) process for further reducing the oil concentration in the produced water before it can be discharged into the ocean. The popularity of hydrocyclone technology in the offshore oil and gas industry is mainly due to its rugged design and low maintenance requirements. However, to operate and control this type of system in an efficient way is far less simple, and alternatively this task imposes a number of key control challenges. Specifically, there is much research to be performed in the direction of dynamic modeling and control of de-oiling hydrocyclone systems. The current solutions rely heavily on empirical trial-and-error approaches. This paper gives a brief review of current hydrocyclone control solutions and the remaining challenges and includes some of our recent work in this topic and ends with a motivation for future work.
To clean the produced water is always a challenging critical issue in the offshore oil & gas industry. By employing the plant-wide control technology, this paper discussed the opportunity to optimize the most popular hydrocyclone-based Produced Water Treatment (PWT) system. The optimizations of the efficiency control of the de-oiling hydrocyclone and the water level control of the upstream separator are discussed and formulated. Some of our latest research results on the analysis and control of slugging flows in production well-pipeline-riser systems are also presented. The ultimate objective of this research is to promote a technical breakthrough in the PWT control design, which can lead to the best environmental protection in the oil & gas production, without sacrificing the production capability and production costs.
Due to the harsh weather conditions, severe spatial limitations and extremely high safety requirements, the indoor climate control for offshore oil & gas production platforms is much more challenging than any on-shore situations. For instance, the indoor pressure of man-board quarters should be kept all the way above the ambient pressure according to safety regulations. Meanwhile, the indoor air needs to be regularly changed in order to guarantee the indoor air quality. Both requirements could be possibly achieved by automatically manipulating either the throttle valve located at the terminal of the inlet channel in the considered Heating Ventilation and Air-Condition (HVAC) system, or the pressurization system located inside the inlet channel, or both of them in a coordinated way. A Model-Predictive Control (MPC) solution to control the inlet throttle has been proposed in our previous work. This paper proposes a set of control solutions to regulate the variable speed pressurization fan system such that the energy efficiency of the considered HVAC system can be explicitly considered. A combined feed-forward with a PI-based feedback control solution, and an MPC solution are proposed based on derived simple system models. Some preliminary simulation results show that both control solutions can keep the indoor pressure and the air circulation in a very satisfactory and robust manner, even subject to the presence of severe disturbances.
The goal of this paper is to introduce and design a cost-effective Oil-in-Water (OiW) measuring instrument, which will be investigated for its value in increasing the efficiency of a deoiling hydrocyclone. The technique investigated is based on Electrical Resistivity Tomography (ERT), whose basic principle is to measure the resistivity of substances from multiple electrodes and from these measurements create a 2-D image of the oil and gas component in the water. This technique requires the measured components to have different electrical resistances, such as seawater which has a lower electrical resistance than hydrocarbon oil and gas. This work involves construction of a pilot plant, for testing the feasibility of ERT for OiW measurements, and further exploring if this measured signal can be applied as a reliable feedback signal in optimization of the hydrocyclone's efficiency. Different algorithms for creating 2-D images and the feasibility of estimating OiW concentrations are studied and evaluated. From both steady state and continuous laminate flow perspectives, with respect to the objective which is to use this measurement for feedback control purposes.
Marine space is overall under increasing pressure from human activities and in the way harming the marine ecosystems. Maritime spatial planning is one of the governance elements in the EU Integrated Maritime Policy (2007) that aims to maximize the sustainable use of the seas and oceans. Maritime spatial planning aims to ensure that the increased use of the marine space takes place in a way that is consistent with the sustainable development in the seas and oceans. According to the MSP Directive it is required to follow an ecosystem-based and thus holistic approach. For this to happen, tools are needed, and some tools are available but with various advantages and disadvantages. The aim of the current research has been to develop a comprehensive package of tools to assess the environmental impacts of societal activities under different maritime spatial planning proposals.