Wellbore Stability Analysis of the Energy-gathered Nesting Technology and Its Application in Karst Formations Drilling Fluid Lost Circulation

ABSTRACT: There is still no effective solution to the cavity-type lost circulation in the drilling and completion of oil, gas and geothermal resources. In this respect, the Energy-Gathered Nesting Plugging technology is proposed and the wellbore stability simulation research of nesting process was carried out. The technology and mechanism of energy-gathered nesting plugging was introduced. The distribution of wellbore, cavity stress, velocity and temperature are analyzed under different impact loads, formation and heat sources in the downhole environment. The study shows that stress distribution around the wellbore remains below 3 GPa, causing minor deformation except in sandstone formations. Explosion-induced stress changes are short-lived and decay rapidly within twice the cavity diameter. The heat generated by the explosion and transferred to the drilling fluid causes a large velocity change, but its area of influence is also very limited. This study can provide a theoretical basis for the study of energy-gathered plugging technology in the cavity formation.