Real-Time Control and Online Parameter Estimation for Drill String Dynamics Modeling

Accessing resources in the subsurface—hydrocarbons, thermal energy or at times, minerals—requires the drilling of a slender wellbore through varied geology. Power for the drillbit is transmitted through a combination of fluid power and mechanical energy along a drill string made up of segments of steel pipe. The aspect ratio of the system, where wellbore diameters range from 10 to 50 cm and depths extend up to 10 km, results in a system with system non-linear dynamics. Sensing of downhole parameters is typically limited and delayed, which presents the need for a sufficient drill string model for parameter estimation. In this talk, you’ll see one such model that has been developed and validated with field data that is based on the one-dimensional wave equation with a distributed friction term. An estimator for the model has been developed to provide an estimate of downhole torques and RPM and is used as a monitoring tool and for real-time control.