Experimental Research On Fricitonal Torque Between Drill String And Wall In Geological Drilling

With the depth of geological prospecting increasing, most part of energy isconsumed in the friction between drill string and wall in the drilling process. In orderto reduce energy consumption, it’s necessary to study frictional torque between drillstring and wall, which is one of the most important frictional problems.The type of friction was determined as sliding and rolling friction, from the motionof drill string, and static friction in some special conditions. Also, the mechanism offriction was summarized according to the force analysis of micro section of drilling,which is that when the micro section was compressed to the hole wall, the contactforce comes out; at the same time the friction also came out along with the motion orthe trend of motion between drill string and the hole wall.According to the condition of drill string in hole wall, the influence factors offriction torque was summarized including material,motion and force of drilling,formation, circulation medium, and environment in the bottom of hole. Then thefriction system was established with the concept in tribology.Rotation speed, and axial force, lateral deformation,contact force and hole wallwas studied with the kind of indoor experiments. Through the analysis of the data, therelationship and the fitting equation between friction torque and factors wassummarized and explained with the adhesion theory.