Analytical model for a cylinder sinking into a thin film

Abstract

New technologies and techniques have enabled oil companies to access oil deposits by drilling through the ground horizontally. These increased capabilities have improved drilling efficiencies, and have also reduced the effects that drilling has on the local environment. These boreholes can be enormously long, and it is often necessary to send a tethered robot into the hole in order to gather information. If these robots remain stationary for too long, however, their tethering cables can become stuck in the mud cake lining the walls. The recovery or replacement of these robots is time consuming and expensive, so it is desirable to understand how and why the cables sink. In this analysis, the mud cake is modeled as a Newtonian fluid. The surface of the cable is approximated as being either parabolic or circular, and it is shown that the sinking is governed by exactly two dimensionless parameters in both cases. Matlab is used to visualize the evolution of the fluid pressure distribution with time, as well as the time it takes for the cylinder to settle to 20 percent of the mud cake thickness.