Study On The Mechanism And Application Of Speed Increase In Torsional Impact Drilling

With the development of oil and gas exploration,some weak points are revealed from the energy transmission system of rotary drilling method,which is reflected in low ROP,poor dynamic safety of drill string and high drilling cost.China's drilling technology level is still very backward.The average cycle of well build and bit usage are about 2 times than that of the United States.Therefore,it is a major engineering problem to increase drilling speed and improve drilling efficiency in deep wells.Base on the study of the energy transmission law of rotary drilling system,it is considered that the torque of the broken rock of PDC bit locates at the end of the torque transmission chain of the drill string.It is the main reason for the low drilling speed and the many derivative problems in the hard drilling of the deep well.And for the example calculation,it is only 5.98% of inputing torque from ground,which passed through the 5000 meters drill string,to the end of the drill.It will occur,PDC bit's stick-slip phenomenon,if the torque is not more than the broken drill critical torque stratum PDC bit required.The more difficult to drill,the more serious the stick-slip is.Severe alternating stress can easily lead to downhole accidents such as drilling tool fracture and falling well,which greatly increases drilling cost and risk.Therefore,this thesis proposes to establish the mechanism of the impact energy supply near the bit,to ensure the dynamic safety of the drill string,to reduce the damage degree of transverse vibration,self excited oscillation and stick-slip.It is solved that the problem of torque transmission of rotary drilling from the source.ROP is the result of the interaction of rock drill drill,performance characteristics,drilling parameters and so on.And its core is the overall stress analysis of PDC bit.In the thesis,it is considered including the rock properties and cutting properties and the rock breaking process.The calculation method of rock crushing angle has been improved.Compared with the rock breaking angle under dynamic load and static load.Rock breaking angle of dynamic load is larger,and the energy consumption of broken rock per unit volume is lower.And this is the theoretical basis for speed up ROP by using dynamic load.This thesis uses the method of experiment and simulation to test and verify the function and performance index of the torsion impact tool.An indoor test system for torsional tools(including hardware and software)has been established.The CFD model of torsion impact tool is established by Fluent software,and the kinematics and dynamics model are established by Adams dynamic analysis software.By using the Ansys finite element software,the strength of its key components has been checked.The fitting curve of tool's performance parameters have been verified and deduced.A near bit impact power tool-SL series torsion impact tool has been developed to sovle the technical bottleneck of energy transmission rotary drilling system.By the end of 2017,the series of tools was successfully applied 191 wells in many areas,include the East China Sea,South China Sea,Sichuan shale gas,Shanxi coalbed methane,Xinjiang,Shengli Oilfield and so on.Its cumulative footage over 68000 meters,and 9 block operation record are hit.The torsion impact tool can increase the impact energy of breaking rock and improve ROP of drilling.More importantly,the whole drilling process torque is very stable.And the dynamic safety condition of drill string is improved.Practice has proved that the method and energy of rock breaking has been has changed and improved.So,it is used to break through the technical bottleneck of the energy transmission of the original rotary drilling.Therefore,the safety and dynamic condition of the system can be improved and guaranteed even during fast drilling.To sum up,theory is the basis,experiment and simulation are methods and practice is the purpose.Based on the logic main line and system thinking,this thesis explores the mechanism of torsional impact drilling speed increase from a systematic perspective,and its application research.