London-based Ecofin Energy Resources plc has agreed to merge with Amadeus Energy Ltd. (ASX: AMU) to create a new oil and gas company worth $200 million.

The combined entity, expected to do business under the name of Ecofin's subsidiary Lonestar Resources, will own a portfolio of assets that includes various U.S. onshore assets with reserves of up to 12.7 million barrels of oil equivalent (MMboe). Among the properties are wells located in the Eagle Ford and Barnett shales in Texas, as well as acreage within the Bakken and Three Forks formations located near Williston Basin, Mont.

The deal is subject to approval by Amadeus shareholders.

The deal was originally announced on Oct. 22. Amadeus is based in Perth, Australia.

Law firm Mayer Brown LLP advised Ecofin on the U.K. and U.S. aspects of the deal, while Herbert Smith Freehills managed Australian matters.