Automation of directional drilling processes has gained interest as drilling operators seek more cost-effective solutions and consistent performance. Automation and control–although a mature topic in many industries–has recently started to take place in the drilling world as well. Hence, there is a great potential for rapid and significant improvements.
Currently, directional drilling operations are primarily managed by directional drillers who make steering decisions based on available pre-job reports, real-time data and geometric calculations. The resulting performance is contingent on directional drillers’ skill set, knowledge of the drilling tool, and familiarity with the local geology. Automating this process brings the promise of standardized drilling decisions with consistent accurate well placement with improved borehole quality, and the flexibility to adapt to new technologies in drilling tools and sensors. Automation also increases safety level in operations by reducing the on-site crew size since directional drillers can remotely manage multiple wells.
This work proposes a model-based control approach for automated steering in drilling operations. Two different models are presented. First, a comprehensive wellbore propagation model which considers multiple factors, such as the geometric feedback embedded in the wellbore trajectory, the drilling tool mechanical properties and actuation principle, the bit/rock interaction laws and kinematic relations between the bit motion and the newly created borehole, then a reduced-order model tailored for control applications. The control approach presented is applicable for both rotary steerable systems (RSS) and mud motors. Testing results are presented and discussed at the end of the paper.