Controlling drop-off angle and deviation prevention

With the development of horizontal-well drilling technology,deviation control by steering drilling and continuous control techniques have been applied in directional wells and straight wells.But drilling cost is increased.In order to achieve the goal of fast drilling with dropping-off angle,deviation-controlled straight drilling,new drop angle and deviation prevention techniques must be adopted.Starting from analysing deviation causes,this paper proposes technique of dropping -off angle using pendulum assembly,preventing deviation with high WOB and slick drill collars,and revolution method preventing deviation.Through actual drilling of directional wells,the results show these methods are practical,can increase ROP several fold and are worth popularizing.