The company said the target Middle Dua sand sequence was encountered as expected and the first zone flowed oil at a sustained rate of 1650 barrels plus 1.4 million cubic feet of gas per day.
The second zone also flowed oil at a sustained rate of 2680bpd and 2.1MMcfd of gas.
No water was produced on either test.
Santos said the rig would now move to drill the Chim Ung and Chim Cong exploration prospects elsewhere in the block.
Acting chief executive David Knox said the positive results from the well were encouraging and the company would work closely with its partners towards a final decision on the Chim Sao development.
Santos International Holdings has a 37.5% interest in Block 12W and operator Premier Oil also has 37.5%, while Delek Energy holds 25%.
