Optimization Design Of Drill String Strength In Ultra-deep Wells In Tarim Oilfield

Drilling tool failure frequently occurs in Kuche and Shanqian area of Tarim.To ensure drilling operation safety,it is necessary to analyze drilling tool failure and optimize drilling tool design in this area.Aiming at the failure phenomenon of Tarim drill tools,this paper has carried out relevant research work.Based on the statistics of drill tool failure accidents in Tarim from 1995 to 2009 and the study of drill tool leakage,the types of drill tool failure in Tarim are summarized,and the possible solutions are put forward through the analysis of the causes and characteristics of the failure.Through the input and analysis of detailed drilling design data of 30 typical ultra-deep wells in Tarim by using the integrated drilling engineering design system software,the stress characteristics of drill string are summarized,and it is found that the design tension margin of Kuche and Shanqian block is generally small.The five-hole drill assembly of Well Keshen 14 is calculated by using the recommended drill string design method in Tarim and passed through the soft one.The strength of the drill string is checked,and it is found that the tensile allowance of the drill string design in Keshen 14 well is too small.After increasing the tensile allowance,the optimal design of the second and third open directional drilling tools combination in Keshen 14 well and Dabei 1-1X well is re-carried out.The strength,tensile and torsional loads are analyzed by software,which proves that it meets the construction requirements and successfully implements the drilling plan.Based on the consultation of on-site experts and practical experience in Tarim,it is suggested that the tensile allowance should be increased on the basis of recommended practices.