We are not going to talk about geosteering, or directional drilling optimization (where the focus is on when and whether to rotate or slide and what toolface to proceed with) in this post. Instead, we will show you how to identify dysfunctions that might be happening when one is slide drilling with a mud motor, so that corrective actions can be taken to mitigate them.
The dysfunctions we will focus on in specific are buckling, high friction, poor toolface control, stick slip (motor stall) and bit bounce. The network that is used to detect these dysfunctions is shown in Slide 2, and the features are introduced briefly in Slide 3.
In this particular post we will primarily focus on high friction. There are three key features that provide indication of this dysfunction – low toolface efficiency index, low DWOB to SWOB ratio and increasing/erratic downhole MSE trend. Check slide 5 for additional information on these three features.
The estimation of DWOB which is an input to one of the features is without doubt a tricky endeavor. We recommend that you check out the papers by Wu and Hareland (2012) and Zha et al. (2018) (SPE-191723-MS) for a deeper understanding of the techniques to calculate DWOB. Both are outstanding papers and laid the foundation for the approach inside Sentinel RT, which is detailed in Slide 6.
There are corrective actions that can be taken to reduce high friction, but before we go into that, we will discuss buckling and poor toolface control as well – two other important dysfunctions that occur during slide drilling. Stay tuned for these – we will be discussing them next week.
Click below for slides on this topic: