The Ande Ande Lumut oil field was discovered in 2000, and is located in the Natuna Sea, close to the Malaysia-Indonesia maritime border. It has lain undeveloped due to the challenges associated with developing the field's heavy crude. The development plan, approved in 2011, includes a wellhead platform linked to an FPSO vessel, and long-reach horizontal wells with electric submersible pump (ESP). The initial development plan only considered the development of the K-Sand reservoir. In June 2016, the Ande-Ande Lumut-4XST1 appraisal well proved that further reserves upside could be unlocked from the G-sand reservoir. Sanction of the project, initially expected in 2014, has been delayed due to the low oil price environment. In February 2016, Santos announced its intention to farm-out part of its stake in North West Natuna while maintaining its operatorship.