Research On The Mixing Device Of Marine Dynamic Kill Drilling

During deep-water-surface well drilling,dynamic kill drilling technology can effectively solve the problem of narrow safety density window,design difficulty of well structure,and the problem that the casing cannot be lowered to a predetermined depth.It is also an effective solution for drilling wells with shallow gas and shallow laminar flow.The mixing device is a key equipment unit of the dynamic kill drilling technology.Mixing efficiency and control accuracy have always been concerned in upgrading equipment,which is also the focus of this study.Based on the principle of safety and efficiency,the overall design programme and control programme of dynamic kill drilling mixing device are given by theoretical analysis and simulation.The key parameters of mixer are optimized by numerical simulation.Finally,the principle prototype is manufactured and tested.Using the multilevel module division method,the functional structure unit module of the mixing device are divided,and a complete design method of the mixing device is proposed.Based on the working principle of dynamic kill drilling technology,considering the influencing factors of the mixer’s mixing efficiency,numerical simulations are conducted to analyze the effects of different mixer capsule,nozzle shapes,nozzle modes and directions,and spoiler on the mixing efficiency and mixing stability of the mixer.The results show that the traditional T type mixer has a large variance of the mixing density when the mixing ratios of the two fluids are close to each other.Based on the theoretical analysis of its internal mechanism,structure parameters of the mixer capsule,nozzle shape,and nozzle injection are optimized.Combined with the on-site technological process,the structure,installation method and the control flow of mixing device are designed in detail,and the prototype machining and testing are completed.The experimental results show that the designed mixing device can quickly mix the basic mud and seawater evenly,and the error is kept within 0.016g/cm~3,which is 20%higher than that of the traditional Y and T type mixer.