Study Of Zhong Yuan Oil Field 133-1 Horizontal Well Drill String Extension Capability

Recently the horizontal well is widely used in the oil and gas reservoirs.But subject to the drill bearing ability,drill string strength,pump rated pump pressure,the purpose layer bearing capacity and cutting beds and other factors influence,horizontal section can not be infinite,so horizontal section can extend how long,and how to improve the level of extension length,become a problem need to be solved.This paper firstly under reasonable assumptions to establish the three dimensional buckling differential equations to solve the different buckling state of drill string buckling critical load.basis soft model,given the different working conditions of the drill string friction torque recursive calculation model,combined with finite element method gives the whole well section of drill string axis force,the friction torque of recursive formula.Then,considering the cuttings bed,joint drill,drill eccentric ity effect on cyclic pressure dissipation,gives the pressure consumption calculation formulae of the correction factors,and combined with the practical riser pressure to amend the circula ting pressure loss calculation.Based on this,given the criteria for determining the mechanical and hydraulic extension limit of the horizontal well drilling and established the method of predicting the extension ability of the horizontal well drill string.Finally through the example of a horizontal well in Zhongyuan O ilfield,analysis and comparison horizontal wells extended limit in different conditions,different artificial slope,different WOB,different discharge and different cuttings bed height.The results show that the buckling of the drill string,the torque of the friction and the debris bed are the key factors to restrict the extension of the drilling string.