Study On Optimization And Experiment Of Hollow DTH Hammer Bit Under Complex Conditions

Nowadays, application of drilling engineering has been more and more widely,especially in the exploitation of mineral resources, so the search foreffective,advanced drilling technology is the goal of all the experts. Hollow-throughDTH reverse circulation continuous coring (sampling) drilling technology with itsgreat advantag has been widely researched and applied by the drilling people. Inrecent years, along with the strength and range of our country to mineral explorationincreasing, encountered various complicated geological conditions and constructionconditions in the drilling, which has brought new difficulties and challenges todrilling prospecting work. Therefore, the key point and difficult point of the drillingpeople is to solve all kinds of drilling problems when encountered complicatedgeological conditions and construction conditions, and also need to be overcome, Themost critical part which affect the effect of reverse circulation drilling is reversecirculation bit, so to optimize the structure of the reverse circulation bit becomes veryimportant.In this paper,based on some theoretical research, simulation analysis andexperimental research on reverse circulation bit, aims to optimize the structure ofreverse circulation bit, in order to improve the effect of reverse circulation, so that ithas a better application of reverse circulation technology in complex conditions.First, study the structure and the design idea of two kinds of reverse circulationbit (a double hole type reverse circulation bit, another is a spline hole type reversecirculation bit) designed for the complex conditions, through the numerical simulationof the flow field on the two bit, study the distribution of the pressure field andvelocity field, get the conclusions: the effect of reverse circulation bit after remove thebottom jet hole is better than the bit with bottom jet hole.Secondly, further study and analysis of some factors affecting the effect of the total internal orifice type reverse circulation bit, including structure parameters,drilling parameters, the size of drilling center channel pressure and so on. This paperanalyszes the internal orifice type reverse circulation bit by using computational fluiddynamics (CFD) method, emphatically analyzes the effect of reverse circulationaffecting by the diversion section length, entrance air volume,center channel pressureof the internal orifice type bit., and gets some conclusions.Finally, in order to analyze and research the effect of reverse circulation onexisting bit and bit to design in laboratory more accurately, a new set of reversecirculation test system is designed. This paper carries out a series of experiments toexisting reverse circulation bit (Φ89mm and Φ108mm) in laboratory, under thecombination of parameters between different bottom jet hole and internal jet hole,different intake air volume, different center channel pressure channel, and gets someimportant conclusions combined with the results of simulation analysis.In a word, this paper makes some simulation analysis and experimental researchof reverse circulation bit used under complex conditions, achieves some beneficialresults, provides a theoretical basis for structure optimization direction of reversecirculation bit in complex conditions, and also provides a favorable technicalreference for the practical application of run-through DTH reverse circulationcontinuous coring technology in the conditons of complex stratum and complicatedconstruction.