Environmental Monitoring

Water Metal Analyzer

Checking the quality of sea water in the vicinity of offshore oil production sites takes place every two months or yearly. Periodic monitoring is performed by collecting in-situ water samples that are then analyzed in specialized laboratories, primarily using chromatographic or spectroscopic techniques for the organic/inorganic contaminant identification, if present in the sample. This type of approach cannot be exploited to implement strategies for prevention of environmental disasters and therefore, since the public opinion and several international regulations require greater attention to the environment care, it is necessary to evolve current monitoring systems into one that can alert in real time an intervention team, so to avoid pollution, often irreversible, of the water.

The exploitation of deposits, whether they are oil or gas, involves the production of waste, including the produced formation water (PFW). PFW is the most relevant type of effluent in the production phase of hydrocarbons on offshore installations, both for the generated volumes and for the level of pollutants potentially present. Downstream the purification treatment, the production of water for the sea discharge appears as a heterogeneous mixture, constituted by an aqueous phase with the residual solid material in suspension. The aqueous phase contains inorganic chemical species (salts, metals and radioisotopes) and organic (mono-compounds, polycyclic aromatic, aliphatic hydrocarbons, ...).

The proposed solution to overcome the current limits in terms of offshore environmental monitoring and significantly improve the operational scenario is that of a sensing platform capable of sampling at least daily (or more frequently as a function of the associated risk analysis) the waters near a site of interest, activating an ON/OFF procedure about the presence or absence of contaminants and eventually preparing the collected samples for a more accurate, quantitative and lawful analysis in case of activated alarm. The design of the platform takes advantage of microfluidic (Lab-On-Chip) technologies for the management of the fluids and the in-situ analysis of marine sample. This approach will involve a dramatic reduction of the sample and reagents volumes, a prolonged monitoring and a greater space coverage around offshore platforms without a noticeable loss of performance in terms of sensitivity.

To provide greater flexibility, the platform has been designed with a structure of independent but integrated modules (sampling, filtering, sample pre-treatment, analysis, data storage, reagent  and any reaction products storage), so as to contain as much as possible the overall dimensions and in order to customize the platform according to the specific requirements.

In the case  the sensors are used in a situation in which a remote monitoring is necessary, they will be equipped with a data transmission system, so that the measurements can be collected, handled and stored. The wireless data transmission channel will be designed so as to make available in real time also the information about the operating status of the sensor platform (failure, alarm, maintenance request, exhaustion reagents, waste filling, ...).

The feasibility study of the sensor platform is focusing on the evaluation of a demonstrator ("case study") dedicated to heavy metal ions (zinc, chromium, nickel, copper, cadmium, mercury, arsenic, ...), because of the high risk related to these contaminants and the potential interest and application in non-oil sectors (drinking water, waste water, ...).

Heavy metals accumulate through the food chain and pose a threat to the species at the top of it, including humans. The biggest problem is in fact that moving from one trophic level to another, the quantity of accumulated toxic substance increases more and more; in this way the predatory organisms at the top of food chains of larger size (ultimately humans) are also the most exposed to the risk of severe intoxication. This phenomenon is called bioaccumulation and biomagnification.

 

Micro Hot-Plate for H2S Sensing

In most industries (the oil & gas above all) one of the basic points of a security plan to reduce the risks for the staff, for the plant and the surrounding environment is the adoption of appropriate alarm systems, such as those based on gas sensors. These allow to take preventive remedies and actions to be taken as parts of a comprehensive, automated and integrated control and safety plan of a facility or a processing site.

The detection of toxic and/or hazardous gas mixtures for the environment and for the workplaces (and in particular, but not exclusively, H2S) finds a particular application in the field of industrial processes, safety at work, control and environmental monitoring.

In particular, the H2S detection is strategically important for many application scenarios. The focus for the H2S is due to its inherent dangers. H2S is a colorless gas, extremely dangerous, characterized by a pungent odor, similar to that of rotten eggs. Even at very low concentrations it is however extremely toxic and can attack and inhibit the smell. In addition, in the appropriate mixing conditions with air or oxygen (flammability range from 4.3 to 45.5%) can be explosive. It dissolves in liquids, therefore, it may be in any container, tank or means of transport of liquids such as oil, water, fuels or emulsions. It has a broad spectrum of toxicity effect, although the nervous system and cellular respiration are the first systems to be attacked following exposure.

It can be found in different working environments, mainly, but not exclusively, those related to oil industry (refineries, oil wells, ...). It may accumulate wherever there is a mixture of hydrocarbons and sulfides. There are several organic sources where you can find the H2S, some almost unexpected, as the holds of ships, mine shafts, pulp mills, water purification plants, quagmire, drains and sewers (H2S is a natural product and is generated by the organic decomposition, for which it is present e.g. also in landfills).

The aim of the activity is therefore the study of a solid state sensor for the monitoring of H2S, with innovative features compared to the state-of-the-art and that integrates advanced technologies. For this purpose, the developed device is based on the convergence of different technologies:

• nanotechnologies: for the growth and the synthesis of the active material (through the partnership with IMEM-CNR) sensitive to the presence of the target gas even at very low concentrations and based essentially on nanostructures of semiconducting metal oxides (ZnO, SnO2, TiO2, ...). The nano structures investigated are Tetrapods (TPs), nanosheets (NSs), or combinations thereof;
• microtechnology and MEMS technologies: for the realization of the suspended microstructure (micro-membrane or micro-hot-plate structure) of electrically and thermally insulating material on which is integrated the above referred active material and the devices for its control (thin film platinum heater and temperature sensor ).

  

 

Contact information

luciano.scaltrito@polito.it

paola.rivolo@polito.it

matteo.cocuzza@infm.polito.it

 

Publications

  1. "A new method to integrate ZnO nano-tetrapods on MEMS micro-hotplates for large scale gas sensor production", S.L. Marasso, A. Tommasi, D. Perrone, M. Cocuzza, R. Mosca, M Villani, A Zappettini and D. Calestani, Nanotechnology, 2016, Vol. 27(38), 385503, doi:10.1088/0957-4484/27/38/385503

 

Partners & Collaborations

IMEM-CNR - Parma

Società Metropolitana Acque Torino S.p.A.

ENI S.p.A.

Tecnomare S.p.A.

Ministero per lo Sviluppo Economico