text: Travira 's aircraft are used for long-term deals with major mineral companies , such as ExxonMobil , West Natuna Consortium , and mining companies in Sumbawa and East Kalimantan .
simplified: Travira 's aircraft are used by big mineral companies including ExxonMobil and West Natuna Consortium . They are also used by mining companies in Sumbawa and East Kalimantan .