The company recently agreed to buy out the interest owned by Eni of Italy, which had been the operator of the prospect. Eni has has been actively marketing much of its US Gulf portfolio for more than a year.
Cobalt will now operate Goodfellow with a 47% interest, up from 29.2% previously.
The deal, which is subject to the other Goodfellow partners' preferential right to purchase, is expected to close later this month.
Goodfellow