(ShareCast News) - Cluff Natural Resources said it had extended its memorandum of understanding (MOU) with Halliburton Manufacturing and Services Limited to collaborate on the development of its Southern North Sea gas assets as well as its Underground Coal Gasification assets, for a further two years.The company said it anticipated that working with Halliburton would continue to facilitate the development of its five Southern North Sea gas licences which are located in close proximity to the Breagh Gas Field and to facilitate the development of CLNR's portfolio of nine UCG licences which provide exposure to five different coal basins in the UK.The MOU will remain in place until 5 February 2018, unless terminated in advance by either party providing 30 days' written notice, Cluff said in a statement.