Study On The Tooth Strength Of Drilling Bit In Geothermal Drilling

Geothermal resources has a widely and abundant distributed in the world. As petroleum resource’s consumption developed, people are getting attention to clean and sustainable geothermal resources. The drilling of high-temperature geothermal resource is different from traditional oil drilling, geothermal wells are always in the tough geological environment areas, mostly igneous rock structure are wear-resistant rock, and there is a lot of drilling fluid leakage cave formations in some serious condition, the hole of bottom temperature can be more than300℃, it resulting the failure of fall off on cone-bit teeth, it’s very common in working time that affecting the drilling’s costs and efficiency, and this problem has little carried out in our country, so that tooth fixing technology of high temperature geothermal well drilling is urgent and important. Main research of this article including:First of all, search and analysis the literature of tooth fall off in geothermal drilling cone bit, comparing geothermal drilling bit and conventional drilling bit to find out the different of structure, materials, loading, working conditions between them, analysis the reason of geothermal drilling cone bit’s tooth off in the base of tooth fall off in conditional cone bit theory, and explain the theory in details.Secondly, calculating the math of the reason for geothermal drilling cone drill out tooth failure, use elastic-plastic mechanics, solid mechanics and thermodynamics theory, combining the formula of normal temperature interference fit fixing tooth force and the high-temperature material variation deduced, analysis out a tooth fixing force formula which apply geothermal drilling cone bit, and checking the result to confirmed the physical causes of tooth of failure.Then, building the analyzing model of geothermal drilling cone bit, study in the principal of metallic material changes by temperature, add the constitutive relations between different temperature in the applications material library, calculating the result of tooth fixing force variation under different structural parameters, the different temperature conditions, and comparing the details of similar kind of experiment to prove the analysis result’s correctness.Finally, Reference room temperature under load data cone bit by rainflow counting method and linear fatigue damage accumulation theory fit the applicable load spectrum, establish geothermal drilling cone bit alternating shock loads fatigue analysis model to study the different parameters of the variable structure at high temperatures influence of the fatigue life of the perforations.Based on the above research, find out feasible idea to enhanced geothermal drilling cone-bit’s tooth fixing force.