Study On Control Measures Of Leakage Blocking By Rotary Jets In Fractured Strata

In Tahe Tuoputai block,crack distribution is very complicated and the Permian igneous rock is hard,brittle,easy to collapse and block out which caused great trouble to drilling.Compared to the conventional plugging technology,plugging technology while drilling has the advantages of good plugging effect,high drilling efficiency,low cost and so on.But in Tahe Tuoputai block,after the leak stoppage is completed used plugging tool while drilling,the strength of wall is not enough and its bearing capacity is poor which can cause leakage again.According to the investigation of the formation of Tahe Tuoputai block,the leakage mechanism is analysed.And on the basis of analyzing and studying the working principle of the plugging tool for drilling,it analyzes the swirl nozzle which is the key components of the tool by using ANSYS-FLUENT simulation software to carry out numerical simulation,and analyzes the influence of the swirl nozzle’s structure parameters which include blade number,nozzle outlet diameter and nozzle mounting angle on the formation of swirling jet in the annulus,and the obtained results are four blades impeller,nozzle outlet diameter with 7 mm,zero installation angle.In this paper,the flow law of drilling fluid in formation fracture and the influence of drilling fluid solid particle size,drilling fluid viscosity on plugging effect by using the numerical simulation method is analysed.At last,the plugging control measures while drilling suited Tahe Tuoputai block is idetermined: drilling plugging drilling fluid solid particle size should be 0.01mm~1mm;the solid volume fraction is 7%~10%;drilling fluid viscosity is 25mPa·s;the well bottom pressure should be controlled within 1.7MPa~7.6MPa;return drilling fluid speed is kept at 0.2~0.5m/s.Finally,the results of this study are applied to the two wells of Tahe Tuoputai block,plugging effect is improved obviously.