Coiled tubing(CT)drilling technology offers significant advantages in terms of cost and efficiency for exploitations of unconventional oil and gas resources.However,the development of CT drilling technol-ogy is restricted by cuttings accumulation in the wellbore due to non-rotation of the drill string and limited circulating capacity.Cuttings cleaning becomes more difficult with the wall resistance of pipe-wellbore annulus on the cutting transport.Accurate description of particle transport process in the pipe-wellbore annulus is,therefore,important for improving the wellbore cleanliness.In this study,high-speed cam-era is used to record and analyze the settling process of particles in the transparent annulus filled with power-law fluids.A total of 540 tests were carried out,involving dimensionless diameters of 0.10-0.95 and particle Reynolds Numbers of 0.01-12.97,revealing the effect of the dimensionless diameter and particle Reynolds number on the annulus wall effect,and the wall factor model with an average relative error of2.75％was established.In addition,a dimensionless parameter,Archimedes number,independent of the settling velocity,was introduced to establish an explicit model of the settling velocity of spherical particles in the vertical annulus,with the average relative error of 7.89％.Finally,a calculation example was provided to show how to use the explicit model of settling velocity in annulus.The results of this study are expected to provide guidance for field engineers to improve the wellbore cleanliness of coiled tubing drilling.

Zhaopeng Zhu;Mengmeng Zhou;Xianzhi Song;Shuo Zhu;Gensheng Li;Zhengming Xu;Xuezhe Yao;Buwen Yu

State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing 102249,China;ARC Research Hub for Computational Particle Technology,Department of Chemical&Biological Engineering,Monash University,Clayton,Victoria 3800,Australia;China University of Geosciences,Beijing 100089,China

颗粒学报（英文版）

[1]Zhaopeng Zhu;Mengmeng Zhou;Xianzhi Song;Shuo Zhu;Gensheng Li;Zhengming Xu;Xuezhe Yao;Buwen Yu-.Settling behavior of spherical particles in vertical annulus:Experimental study and model development)[J].颗粒学报（英文版）,2022(09):114-123

exploitations,Cuttings,of2

Settling,behavior,spherical,particles,vertical,annulus,Experimental,study,model,development,Coiled,tubing,drilling,technology,offers,significant,advantages,terms,cost,efficiency,unconventional,gas,resources,However,restricted,by,cuttings,accumulation,wellbore,due,rotation,string,limited,circulating,capacity,cleaning,becomes,more,difficult,wall,resistance,pipe,transport,Accurate,description,process,therefore,important,improving,cleanliness,In,this,high,speed,cam,used,record,analyze,settling,transparent,filled,power,law,fluids,total,tests,were,carried,out,involving,dimensionless,diameters,Reynolds,Numbers,revealing,effect,number,average,relative,error,was,established,addition,parameter,Archimedes,independent,velocity,introduced,explicit,Finally,calculation,example,provided,show,results,expected,guidance,field,engineers,improve,coiled

0.484476