Study On Prevention Technologies Of Deep Well Drilling Tool Failure In Dagang Oilfield

In deep well of Dagang oilfield, the hardness and discontinuity of rock is big. The longitudinal and torsional vibration of drilling string is strong while drilling. The fracture failure accidents of drilling assembly are often occurred and drilling tools' failure has become block up the exploration and development drilling for deep well of Dagang oilfield.Firstly this paper analyzed the failure mechanism of deep well drilling tools in Dagang oil field and gave the causes of failure are dynamic strength failure and high-frequency stress fatigue failure in the area. By analyzing the mechanical behavior of deep well drilling tool assembly, based on the study of drilling string statics, the behavior of dynamic and fatigue failure was analyzed. The dynamic and kinematic models and computational method of drilling tools failure were established. Based on this, according to the design principles of drilling tool assembly, the bottom hole assembly design and drill twist computational method were given. The drilling trend predictive model of bottom hole assembly was proposed. Finally according to the drilling assembly mechanical model, through analysis the Qishen six riding position of different centralizers and drilling tools stress on different bit weight speed, the reasonable structure of bottom hole assembly and the drilling parameter optimization results for delaying drilling tools strength failure and high-frequency stress failure were given.Through optimizing drilling parameters and bottom-hole assembly structural parameters, reducing the working stress level of bottom drilling tools, the failure accidents were effectively resolved and prevented. It has an important theoretical significance and site actual application value for increasing deep well drilling speed, cutting down the cost of drilling and accelerating the pace of deep well exploratory development in Dagang oil field.