More than 220 jobs are set to go with the closure of Schlumberger's site in Newtownabbey, according to trade union Unite.
One of the world's biggest oilfield services companies, the local plant is located at Monkstown Industrial Estate.
Susan Fitzgerald, Unite Regional Industrial Officer said: “This is devastating news for the more than 220 workers employed at the site who now face losing their jobs as a result of this decision made by Schlumberger’s global corporate management.
"The company is a key employer in the Newtownabbey area which will suffer the impact from the loss of jobs in this high value-added company. Today’s announcement is also another hammer blow for Northern Ireland’s manufacturing sector.
“Unite will be seeking urgent meetings with Schlumberger to demand answers as to how they can justify a decision to close their site in Northern Ireland when the crunch affecting the oil and gas sector is a global one and affects all locations equally. We are aware that they have transferred much activity formerly conducted onsite at Newtownabbey to other, low-cost locations, including China.
“We are concerned that the company’s global corporate management are attempting to use the downturn in the oil and gas sector as cover to further outsource jobs to low cost alternative locations. If so we will be rejecting their logic.
“Notwithstanding those fears, Unite will be engaging with management to seek answers to our questions on the rationale for the closure. Our objective remains to avoid closure and to save the maximum number of jobs possible."