UKF-based estimation fusion of Underbalanced Drilling Process using pressure sensors

Under Balanced Drilling Process (UBD) is a drilling technique that is usually used as a remedy for the drawbacks of the Over Balanced Drilling (OBD) processes. It is an unconventional drilling procedure which adds the ability of production from the reservoir while drilling and reducing or total elimination of formation damage from the drilling fluid as well as faster drilling rates. Faster drilling and less formation damage can be the economical motivation and added benefit for UBD. However, there exist several limitations of the UBD process parameters which make the monitoring and controlling a necessary task. Because of several limitations on mixture velocities in the annulus, an Unscented Kalman Filter (UKF) approach is introduced to monitor the mixture velocity inside the drillstring and in the annular sections. To improve the monitoring of an actual UBD process, pressure sensors were installed mostly in the annulus to enhance the accuracy and robustness of monitoring and an estimation fusion scheme was developed. This paper illustrates a new efficient estimation fusion scheme for both types of central and distributed configurations, leading to new tool for UBD processes modeling.