The Bir Ben Tartar development lease is located in south east Tunisia and contains the TT oil field. Medco Energi operates the development with an 86% working interest. The lease was awarded to Chinook Energy and Cygam Energy in April 2011 following the discovery of the field in 2008. Production started in 2009 from a single well on an extended test, increasing in 2011 following appraisal and development drilling. The development includes vertical and horizontal wells, which are fracture stimulated to improve reservoir performance. In August 2014, Medco Energy acquired Chinook's entire Tunisian portfolio for US$128 million. Water cut in some of the fracture-stimulated horizontal wells, and the high relative cost of horizontal drilling, means that the future drilling programme will consist of vertical wells. The relative isolation of the field requires the oil to be trucked to the La Skhira export terminal. As such, the project is sensitive to operating costs.