Study On The Mechanism Of The Tooth Teeth In The High Temperature Geothermal Well

With the constantly consumption of energy reserves in the world, high temperature geothermal energy has drawn the attention of the world because of its sustainability and non-pollution. Drilling of the high temperature geothermal energy is different from conventional oil and gas, it has complicated geological conditions, been high temperatures above200degrees Celsius. What condition in the geothermal cause the teeth in the cone bit dropped which had affected the drilling effect greatly.The mechanism of the tri-cone bit tooth fall-off is evidently different from that appearing in conventional oil and gas drilling. It can neither evaluate the intensity of tooth fixing in high temperature geothermal well by the measure usually used to detect the intensity of tooth fixing axial loading nor the study of mechanism of tooth fall-off. Therefor the new way to detect the intensity of tooth fixing is been raised in this paper which guides the high temperature fixing tooth experiment. It can has a new recognition of the phenomenon of tooth fall-off in high temperature geothermal well drilling by the analysis of the experiment results.Main content of this paper including:(1) Analysis the reason of tri-cone bit tooth fall-off synthesizing the disadvantage of the tooth fixing technique use in conventional oil and gas drilling;(2) Theoretical calculation including tooth fall-off proof theory analysis, stress analysis of borehole wall and stress analysis of orifice. Completing finite element simulation;(3) Designing and conducting the tri-cone bit tooth fixing experiment in high temperature involving effect of magnitude of interference, temperature, space between teeth and so on;(4) Sum up the cause of tooth fall-off in high temperature drilling combining theory analysis and experimental study, building new way to analysis the tri-cone bit intensity of tooth fixing systematically, making a proposal for tri-cone bit tooth fixing used in high temperature geothermal well drilling.Study shows that the reason for tri-cone bit tooth fall-off in high temperature geothermal well including:(1) Cone bit working in high temperature environment for long hours will lead to the body materials plastic deformation and reduce the body material strength.(2) High temperature will reduce the interference due to the diversity of coefficient of thermal expansion, which will decrease the intensity of tooth fixing.(3) Circulation fluid fail to clean the wall hole due to serious circulation fluid lost which will lead to sand settling and rock bit buried. The bit surface could not get cool. It also increases the body abrasion by the rock debris.(4) Poor formation homogeneity will increase the load of the cone teeth., which will induce teeth fall-off in some degree.