Frequently asked questions

During ONE-Dyas’ discussions with stakeholders, a large number of questions were asked and answered. We have listed them here. Is your question not included? Please feel free to send us an e-mail. You will get an answer as soon as possible.

Usefulness and necessity of gas

The Netherlands is committed to a CO2-neutral energy supply by 2050. During this energy transition, the Netherlands will still need gas. Gas production in the Netherlands is less polluting and cheaper than gas from abroad. Therefore, the Netherlands will continue to produce gas where this can be done safely and responsibly.

ONE-Dyas is investigating whether the production (and possibly also the drilling) platform can be electrified via an electricity supply from a German wind farm. Up until now, electricity has been generated using gas and diesel. Existing technology can be used for the mitigation of emissions to the air, whereby ONE-Dyas will take additional steps to further mitigate the emissions. By applying the latest knowledge and expertise, ONE-Dyas wants to contribute to the promotion of the energy transition.

Obstruction of view

The drilling and production platform will be located about 20 kilometres north of Schiermonnikoog and Borkum. The platform will rise approximately 50 metres above the water surface and, in clear weather, will be visible from Schiermonnikoog and Borkum. The visible size is comparable to the height of passing ships.

Drilling platform (6 July 2017)) seen from Strandpaviljoen de Marlijn, Schiermonnikoog. This temporary drilling platform was at the intended platform location and had a height of 138 meters.

ONE-Dyas wants to reduce the visibility of the offshore infrastructure as much as possible by choosing the lowest possible platform. The intended location offers the best opportunities for drilling multiple gas fields from a single production platform. At the same time, the northern location ensures minimum visibility from the West and East Frisian Islands.

Impact on nature and the environment

ONE-Dyas is investigating the possibility of running the processes on the production platform on electricity. ONE-Dyas is also investigating whether it is possible to run the drilling platform on wind energy and connect it to the neighbouring Borkum-Riffgat wind farm. This will lead to an even more significant reduction in emissions.

ONE-Dyas will commission a plume study to find out where the turbidity and deposition take place. ONE-Dyas will also investigate whether and how much damage this causes to shellfish, fish and fish larvae. ONE-Dyas wants to reduce the discharge of drilling fluid and drill cuttings. This is done by changing the order of the drilling of the different sections of the wells. This means that the Water-Based Mud (WBM) can be used for longer, thus reducing the need for and need for discharges.  For some underground rocks it is necessary to use Oil-Based Mud (OBM). The OBM and drill cuttings from these sections are brought ashore and processed there.

Piling the first steel tube (conductor, diameter: 75-90 centimetres) to a depth of about 50 to 80 metres below the seabed is the loudest sound source during drilling operations. The impact can be limited by various techniques that reduce underwater noise to standards that do not harm marine mammals, including:

  • drilling or vibro-driving the conductor instead of pile driving it
  • using bubble screens

During the seismic survey, underwater noise is generated by the use of so-called ‘air guns’. When the ‘soft-start’ technology is used, marine mammals are encouraged to swim away from the seismic source at the beginning of the survey. Experience in the last five years indicates that the use of this technology can exclude temporary or permanent hearing damage of these animals. Research has shown that within a few hours after the seismic survey is completed, the marine mammals return. Special attention is paid to avoiding impact on the calves born between April and August. No seismic surveys will be carried out during this period.

Mussels and oysters respond to underwater noise by closing their valves, causing food intake to stop temporarily. ONE-Dyas has commissioned a study of the existing literature on the subject. ONE-Dyas is also prepared to commission additional research into effects on non-protected species such as shellfish and marine crustaceans. The EIA examines which techniques can be used to minimise the impact of the activities.

ONE-Dyas wants to limit the occurrence and duration of flaring as much as possible. ONE-Dyas, therefore, wants to use the treatment process as much as possible to test newly drilled gas fields after drilling. If flaring is necessary, a birdwatcher is called in to advise on the appropriate time for flaring. Flaring is, as much as possible, done during the day. This protocol is applied by ONE-Dyas by default and so far there have been no incidents with birds.

Gas extraction and nature development need not be mutually exclusive. No other activity may take place within 500 metres surrounding a drilling platform. This means, for example, that no shipping or (trawl) fishing is allowed. This allows marine life to develop undisturbed. The platform provides a hard substrate on which flora and fauna (including shellfish) can develop. Together with nature organisations, ONE-Dyas wants to draw up a monitoring proposal for new research.

At the end of the extraction process, all boreholes will be decommissioned. The platform will be removed, the anchoring posts and conductor are then cut and removed 6 metres below the seabed. This means that fishing gear cannot get caught in it. ONE-Dyas will first draw up a work plan, which must be approved by the State Supervision of Mines. Everything will be restored to its original state.

ONE-Dyas is aware of the impact that the project can have on the environment. ONE-Dyas wants to be a reliable partner and good neighbour. ONE-Dyas explicitly and proactively seeks dialogue and possible cooperation with stakeholders. ONE-Dyas aims to exclude cumulation, to mitigate the impact and to look for ways to create social added value by contributing to the energy transition and nature development.

Soil subsidence

The probability and extent of the subsidence are described in the soil subsidence report, which is drawn up by an independent research firm. The effects of subsidence on nature and the environment are discussed in the EIA. The soil subsidence report and the seismic risk analysis form part of the extraction plan, for which the Dutch Ministry of Economic Affairs and Climate Policy must give its approval. The extraction plan and the consent shall be made available for inspection.

For shellfish, water depth is one of the factors that determine whether they thrive at a location. Currents and salinity also play a role. An increase in water depth may therefore affect the occurrence of shellfish. Oysters can be found in water depths of up to 60 metres. N05-A is located in the German Bight, which is known as a dynamic environment with strong winds, tidal currents and waves up to six metres high. The dynamics of these three phenomena affect the movement of sand. The average water depth at N05-A is over 20 metres. A few centimetres will hardly make a difference in this dynamic environment. The effects of increasing water depth on shellfish are further investigated in the EIA.

The geological composition of the GEMS area and the gas reservoir consists of good permeable sandstone. It probably will not be necessary to use fracking. The technology used in such cases, including the possible application of hydraulic stimulation, is described in the extraction plan.


Shipping is prohibited in a zone of 500 metres around a platform. The platform will be equipped with an Automatic Identification System (AIS). This is an anti-collision system in which the alarm sounds well before a possible collision l may occur. Each gas well contains a subsurface safety valve, which automatically closes the well in case of a collision . Navigation lights are also used and a stand-by vessel is always present during drilling operations. ONE-Dyas always conducts several safety studies for new and existing activities, including an investigation into collision risks. The EIA will contain a separate chapter on safety and the related environmental effects