The Compound Drilling Technology Research In North JiangSu

Compound drilling methods plays a great role in controlling the wellbore trace continuously and reducing tripping times,and at the same time it can also increase the rate of penetration,which is an efficient way of controllable drilling and has received extensive attention and a wide range of practical applications.Normal PDC bit is mainly used in rotary drilling design with great torque required.Under the condition of a certain weight on bit,downhole drilling strings are prone to reducing the speed or stopping,which cannot reach the desired effect of compound drilling.Considering the formation drillability evaluation and the special demand of compound drilling technique in North JiangSu block,a new compound drilling with PDC bit is developed,which is of great significance in raising the overall drilling speed of North JiangSu block.Bottom hole flow field is the direct performance of drilling hydraulic problems.Through analyzing the flow phenomenon in bottom hole,the problem caused by the drill can be understood more thoroughly,and the relevant structural improvement of the drill can be made more reasonably,such as the injecting nozzle and chip removal groove design.Due to the structure of PDC bit bottom hole flow field is very complicated,belonging to the three-dimensional non-free jet stream turbulent flow field,the common theoretical and experimental methods are hard to describe the bottom hole jet flow characteristics.The bottom hole flow field of PDC bit is analyzed by the fluid dynamics simulation software.Based on the mathematical model of the PDC bit,the optimum design structure of hydraulic characteristic value is developed,which provides a reliable theoretical basis and method for the optimal design of PDC bit hydraulic mechanism.The research results are of great practical significance to optimize the hydraulic structure of PDC bit and improve the dynamic characteristics of PDC bit.Based on the principle of compound drilling technique,the method to improve the drilling speed and inclination mechanism is discussed.Combined with the selection of drilling parameters,the theory of directional deflection ability and drill string mechanics in the compound drilling is studied.According to the characteristics of North JiangSu,the compound drilling technique can be used to prevent the barrier touch.In the drilling process of the small target well and shallow directional well,aiming at the well trajectory problem,the field matching control technology is developed.