Optimized Design Of Drill String For Ultra-deep Horizontal Wells

Drill string design is one of key technology that can be used for drilling in the ultra-deep horizontal wells.Based on the soft string model of drilling string,equations for calculating frictional resistance and torque for ultra-deep horizontal well is derived in this paper.“Matlab” was used to write the software at the same time,considering the practical drilling progress comprehensively and then calculating the effective stress of the drill string and using effective safety coefficient method for intensity analysis of the drill string.As a result,a set of independent complete strength checking method was formed.In addition,the paper mainly analyzes how to optimize design strings of ultra-deep horizontal well which combines with force of the whole string and its subassemblies and come into being the entire optimization design with subsection optimization configuration design method.In the end,based on the analysis of the CMR ultra-deep horizontal well,the design is carried out by the respectively use of the subsection optimization and overall optimization design methods and proceed with the comparison between the calculated results and the designed results by “wellplan” which showed a high consistency.