Dar Petroleum Operating Co. has resumed producing oil from a number of its wells in South Sudan after almost a year, people with knowledge of the matter said.

The company, operated by China National Petroleum Corp., China Petroleum & Chemical Corp. and state-owned Nile Petroleum Corp., has reopened four batches of wells, one of the people said, asking not to be identified as they are not authorized to speak publicly on the matter.

Block 3 and Block 7 in the Upper Nile State, which account for three-quarters of South Sudan’s overall output, were shut a year ago when neighboring Sudan declared a force majeure on its pipeline. The stoppage was lifted in January after about 10 months of no exports, which had throttled the biggest source of revenue for the nation.

South Sudan, which seceded from Sudan in 2011 but still relies on its northern neighbor for a network of pipelines, refineries and ports, is targeting crude production of as much as 90,000 barrels a day (bpd) within six months of the resumption, Oil Minister Puot Kang Chol said last month.

The minister and his undersecretary didn’t respond to text messages seeking comment about the resumption of oil production.