1- Down hole problems A- stuck pipe: When the drill string is no longer free to move up, down, or rotate as the driller wants it to, the drill pipe is stuck. Sticking can occur while drilling, making a connection, logging, testing, or during any kind of operation which involves leaving the equipment in the hole. B- Shale Instability 3- Unconsolidated Formation 4-Fractured Formation 5- Cement Blocks B- LOST CIRCULATION C- WELL CONTROL Source: Manar Chirine KHITER, LinkedIn Herish .w. noree , Kirkuk oil training institute