The deal, initially agreed in March, sees Rose take a 75% stake in a package of leases spanning 195,000 acres in Grand and Emery Counties, Utah. A further 35,000 acres have now been added to the venture, taking the total lease position to 230,000 acres.
Rose said the newly added area was omitted from the original arrangement because of an apparent accounting error at the US Bureau of Land Management.
The company is becoming the operator for the shale venture, which is targeting two prolific plays – the Mancos Shale and Paradox.
"With the total acreage now at 230,000 acres, covering both the Mancos and Paradox formations, Rose has the opportunity to become a significant player in the US oil & gas Industry,” said chief executive Mathew Idiens.
“The resource evaluation report being compiled by Ryder Scott Company is being completed over the total 230,000 acres and we anticipate being in a position to announce this shortly."