Analysis Of Thread Stress Of Oil Drill And Development Of Thread Reduction Coating

In the development of oil and gas drilling,oil drilling tools are the general name of downhole tools,and are important component of drilling and mining equipment,mainly including drill pipe,drill collar,crossover sub,bit etc.The oil drilling assembly are mainly connected by a series of conical pipe threads with a taper of 1:4 or 1:6.Hence,the threaded form of oil drilling tool and the surface treatment of the thread are directly related to the life and reliability of the tool.Of course.the selection of war-resistant high-strength metal materials is major measure to improve the lefe of the drill,but the cost is relatively high.According to relevant analysis data,most of the failure of oil drilling tools occurs at the joints,mainly caused by the guling of joint threads.The copper plating or phosphating process commonly used in the joint surface of oil drilling tools at home and abroad to prevent the gluing failure,although the copper plating can show excellent anti-gap performance,but the copper plating will generate a lot of waste liquid discharge,the damage to the natural environment is huge,so there are defects such as high economic costs and serious environment problems.This research has developed a nano-coppernon-contaminant bonding technology that can replace the copper plating process and has excellent anti-gap performance.The anti-friction effect of a nano-copper antifriction coating on the oil pipe thread.Through theoretical calculations and software analysis of the rechanical properties of oil drilling tool threads,nano-copper non-polluting joining technology has a significant role in the application of oil drilling tools.A digital model and a three-dimensional nodel are established for oil drill pipe joint ghreads(NC38),and the stress and deformation of single tooth threads ard theoretical calculated and simulated.The coneact pretsure and distribution of the tooth surface after the internal and external thread connection were calculated and analyzed under three working conditions:the upper buckle torque acting alone,the axial tensile load acting alone and the combination of the two.The results show that the contact pressure and stress level of the oil drill thread are the decreasing trend and uneven distribution.Through the comparison of the theoretical calculation and simulation analysis results of the thread contact stress of the drilling tool,it is found that the data distribution law obtained by the two methods is extremely consistent,which provides a theoretical basis and application guidance for Nano-copper antifriction coating(hereinafter referred to as AFRICO)AFRICO in the pollution-free connection technology of oil drilling tools.AFRICO is applied to the thread of the oil drill joint and the thread surface of the oil casing coupling.First,testing the antifriction performance of ATRICO with a friction-wear test;Secondly,observing the distribution of AFRICO on the thread surface layer of the oil drill joint with scanning electron microscopy;Finally,the full-size shackle test was carried out on the oil drill pipe of material 4145H and the oil casing of material K55,in order to verify the AFRICO's effect on the torque reduction of the oil drilling tool and the anti-gap effect.The result shows:AFRICO can effectively reduce the upper buckle torque of the oil drill thread connection,and has a good improvement effect on the anti-adhesive performance of the oil drill.