Research On The PDC Bit Personalized Design And The Drilling Rate Model

With the widely used of the PDC bit drilling technology,enhancing the drilling efficiency and reducing the drilling costs of the PDC bit drilling technology get more and more attention by the researchers domestic and overseas.The PDC bit personalized design and the drilling rate model are the theoretical basis of enhancing the drilling efficiency and reducing the drilling costs of the PDC bit.In this paper,intensive studies are made of the PDC bit personalized design and the drilling rate model by the method combining indoor platform experiment,numerical calculation with theoretical analysis.(1)There are 21 special test bits with different parameter combination have been designed by the PDC bit 3D design software in UG(NX 10.0).In order to study the influences of structure parameters such as the cutters size,cutters back rack angle and cutters density on the efficiency of rock breaking,the drilling rate experiment was carried out respectively in drilling red sandstone,yellow sandstone,white sandstone,malmstone,granite,basalt whoes drillability grade value are 2.456,3.821,4.738,5.671,7.565,8.611 through the XY-2B drill rig.The experimental results show that:(1)The cutter parameters have significant impacts on rock fragmentation efficiency of the PDC bits,and with the increase of rock drillability grade value,the cutter parameters impacts on rock fragmentation efficiency of the PDC bits are decreased obviously.(2)There are two different regulars between the PDC bit cutter size and rock fragmentation efficiency when the rock drillability grade above and below Ⅲ.The ROP of the PDC bits increasing as the increasing of the cutter size rock when the rock drillability grade under Ⅲ;but when the rock drillability grade between Ⅲ~Ⅷ,the ROP of the PDC bit reach the top when the cutters size is 16 mm.(3)The rock fragmentation efficiency reducing by the increasing of cutters back rack angle.(4)The rock fragmentation efficiency reducing by the increasing of cutters density.(2)The influence rules of the cutter structure parameters and the rock fragmentation efficiency have been studied by analysising and summarizing the test data.(3)By a process of experimental rules analysis the cutter structure parameters were optimized design,which provides guidance for improving PDC drilling efficiency.(4)The drilling rate equation in two variables(WOB and RPM)of PDC bit has been established,and the correctness of PDC bit drilling rate equation has been verified by the error comparison between calculated values and measured values of some examples.