By Gary Thomas
Air Products will be installing and operating an air separation unit for the supply of nitrogen to Nederlandse Aardolie Maatschappij B.V. (NAM) to enable the latter to extract natural gas from small depleted reserves. NAM is a joint venture between Esso and Shell.
Air Products has obtained the permit and environmental approvals for the installation. Construction will commence shortly. The air separation unit is scheduled to be operational in the summer of 2013. The unit will be situated adjacent to the De Wijk gas field in close proximity to Hoogeveen in Drenthe province in Netherlands.
There are close to 175 small oil and gas fields in the Netherlands portion of the North Sea. Most of these fields are near depletion. The government has decided to focus on the natural gas extraction from the small fields in order to conserve the gas reserves near Slochteren. Aardgas+ (Natural gas +) is the name of the project NAM has undertaken to facilitate further extraction from the depleted reserves. The extraction of natural gas is enabled by the natural pressure of the gas field which forces the gas upwards. Sustained extraction lowers the gas field pressure that makes it difficult to extract the remaining reserves in a viable way. There are new techniques to increase the gas pressure in the field for easy extraction such as the introduction of nitrogen at high pressure into the sandstone layers that hold the gas. The nitrogen will be extracted from the atmosphere through a cryogenic process and will be purified before it is compressed to a pressure of 130 atmospheres. The compressed nitrogen will be introduced via injection units to a depth of 1500 meters into the gas field.