Measuring Wellbore Friction During Workover Operations


Walter Phillips, Wansco

Workover operations effectively probe the wellbore using the rods or tubing. Friction encountered as the rods or tubing pass through the wellbore can be measured at surface. By applying wave equation methods to eliminate surface dynamics, a measure of friction acting along the remaining rods can be quantified. Because the workover process methodically removes rods, a map of friction through the wellbore can be obtained. The act of pulling rods is virtually identical to a deep rod part, and each pull of the rods eliminates friction previously acting below the remaining rods. All that is required is a device that can log detailed load and position on the workover rig. This paper will discuss the prototype device and preliminary results. Two fundamental methods for obtaining wellbore friction utilizing the workover rig will be presented. The wave equation methodology for dynamic motion during normal rig operations, and a static friction approach to determine specific location of downhole sticking by requiring the rig to slowly pull rods periodically. The current and only method for determining rod side-load and friction is to calculate geometry from deviation surveys. The friction map vs depth obtained from the direct measurements can be overlaid on the deviation survey to better determine the behavior of the rod lift system.