Oil and gas producer Santos is putting off 100 staff, most of them Adelaide-based office workers.
They include analysts and finance and planning staff.
The rest of the jobs are going from operations at outback Moomba.
The retrenchments will happen over the first quarter of next year.
A Santos official said the decision has been made to ensure its operations in the eastern states remained cost-competitive.
Santos says it remains committed to South Australia, with a plan to invest $2.5 billion over the next five years and create 500 jobs, most connected with its shale gas program.
In October, Santos turned on the nation's first natural shale gas well at Moomba.