DRILLING TECHNOLOGY IN WELL DK-586 IN QATAR

Well DK-586 is a horizontal well drilled by Shengli Company in Qatar, with its bottom depth at 3683m, a horizontal displacement of 1852m, and a vertical depth of 1943m. It lists as one of the longest horizontal wells on land Qatar, and its horizontal interval extends as long as 1631.6 m. The geological condition is very complex, e.g., soft formation, high dip angle, and hard layers, severe lost circulations are encountered. MWD tool is applied during directional drilling, while in the 3rd phrase and build up section, 1.25° bent housing extended motor is used, and ?120mm motor is used in the horizontal interval. To reduce torque and drag, highly viscous drilling fluid is frequently added in during drilling. Lost circulation is so tough that no returns come out, and drilling can be only continued by pumping water in the hole. Hole deviation is controlled by adjusting weight on bit. Rotary drilling is conducted most of the time, and slide drilling is cut down to only 3.62% of the total footage.