Air Products has announced it will build and operate a new air separation unit for Nederlandse Aardolie Maatschappij B.V. (NAM), a joint venture between Shell and Esso.
The company has secured the necessary environmental and permit approvals and construction will start at the site shortly. The installation is expected to be onstream in summer 2013 and is located next to the De Wijk gas field near Hoogeveen in the province of Drenthe, The Netherlands.
The new unit will be built to supply nitrogen for the extraction of natural gas from small gas fields. The nitrogen, injected at high pressure, will make it easier and more efficient for NAM to extract the remaining 10% of gas from the depleted field. The Netherlands and the Dutch part of the North Sea contain some 175 small oil and gas fields, some of which are almost depleted. In order to preserve the gas reserves in the field near Slochteren, the government has decided to prioritise the extraction of natural gas from small fields.
To enable additional gas production from the depleted field, NAM has set up its own project under the name Aardgas+ (Natural gas +). “Natural gas is normally extracted by being forced up by the natural pressure in the gas field itself. The more gas that is extracted, the lower the pressure in the gas field becomes and the more difficult it is to extract the rest. In general, the last ten percent in a field cannot be extracted economically,” says Hans van Kempen, Head of NAM Onshore Projects.
“It can be done, however, using new techniques. Injecting nitrogen at high pressure into the sandstone strata containing the gas increases the pressure in the field, and additional natural gas can be extracted more easily.” The first NAM gas field to use the technology is the De Wijk field near Hoogeveen in the province of Drenthe. Air Products is constructing an air separation plant, which will use a cryogenic process to extract nitrogen from the atmosphere, at the existing De Wijk-20 site close to the Hoogeveensche Vaart. The nitrogen will be purified and then brought to a pressure of up to 130 atmospheres using compressors. It will then be injected through various injection units into the gas field to a depth of up to 1500 metres.
The De Wijk gas field has been in production since 1954 and has so far yielded some 14.5 billion cubic metres of gas. Thanks to the new technology, it will be possible to extract the last two bln cubic metres in the next 10 to 15 years. This quantity is sufficient to supply all the households in Drenthe with natural gas for six years. Air Products has secured the necessary environmental and permit approvals for the new installation. This follows extensive consultation, including information evenings, held with landowners, local authorities, local inhabitants and other interested parties.
Air Products and NAM have placed a lot of importance on the visual impact of the facility and subsequently conducted an investigation to ensure this was part of the final design. With a view to blending the plant into its surrounding environment, the air separation installation will sit below 20 metres in height instead of the standard 40 metres. The utilisation of tree planting will also reduce the installations external visibility.
“We are particularly proud of the collaboration with NAM,” says Howard Castle-Smith, vice president Tonnage Gases Europe at Air Products. “We have wide experience of comparable projects in the oil industry and are happy that we can also apply our technology in the Netherlands, where we have existing nitrogen business supporting the LNG market. We have been working closely with NAM on developing a technical concept that will fit in seamlessly with the environment and will meet all requirements. Thanks to its modular construction, it will be possible to dismantle the installation when extraction from the field is completed and to reassemble it at another field.”