Last month the company, a subsidiary of Chinese state-owned CNOOC Ltd., was ordered to cease operating 95 pipelines.
The suspensions came as the regulator was investigating a July 15 pipeline spill at Nexen's Long Lake operation that leaked about five million litres of bitumen, produced water and sand into muskeg.
The regulator says on Sept. 6 it lifted most of the suspension order and on Wednesday lifted the order on another 10 production pipelines.
But it says some pipeline operations remain suspended and will not be allowed to return to service until Nexen can show they can be operated safely.
Nexen says it is committed to managing its operations in a safe, environmentally and socially responsible manner.
The regulator says Nexen could still face penalties including prosecution depending on the results of an ongoing investigation.
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