Study On The Rock Fragmentation Mechanism Of PDC Bit

Oil drilling is an important part of oil and gas exploration,PDC drill bit is one of the drilling equipment,its performance is an important factor affecting the efficiency of drilling,and relates to the safety of the system and the success or failure of the whole work.So,it is very important to study the rock breaking mechanism of PDC bit and improve the efficiency and life of rock breaking,we investigated the behavior of cutting teeth in a dry environment,mud environment and mud environment with polyether polyol additivesThrough the simulation conditions,we developed our own test equipment.Test machine is divided into: loading system,rotating system,acquisition system,basing.The loading system is mainly applied by electric cylinder.Rotation system is mainly applied by motor and reducer.The machine can control the speed of the PDC,and collect its cutting force.In this paper,in different eating depth and different forward angle,we study the PDC performance on sandstone and limestone in dry conditions.The results show: The cutting force of the PDC cutting tooth increases with the increase of the forward angle,which is the exponential function relation;the cutting force of PDC cutting teeth increases with the increase of the depth of eating,which is a linear function.Under water-based drilling fluid conditions,the relationship between the cutting force of the PDC cutting tooth and the forward angle and the depth of eating is consistent with that in the dry condition.PDC cutting tooth cutting force compared to the drying conditions from the decline,cutting sandstone cutting force reduced by 15%-30%,cutting limestone 5%-20%.In the polyether polyol water-based drilling fluid conditions,the cutting force of the cutting teeth and the cutting force of the water-based drilling fluid without the addition of polypropylene glycol are substantially the same,and there is no significant change.In terms of finite element modeling,comparing the results obtained by modeling with experiments,show: the simulated cutting force is roughly the same as the experimental rule,proving that the model is effective.