Applied Real-Time Data Analytics Improves Drillstring Life and Design
Authors: Martinez Eddie , Ardoin Andrea , Cheatham Curtis , Whitney Russell 
Published: February 2020

This paper describes how one Permian operator used analytics and torque and drag modeling in real time to gain situational awareness of ongoing poor weight transfer during slide drilling in a lateral. Much-higher-than-planned dogleg severity caused severe helical buckling that decreased rate of penetration and ultimately resulted in damaged drillpipe in the buckled region. Because of the model's predictions of drillstring abuse, the operator ordered a post-well inspection earlier than usual that helped prevent drillstring failure on subsequent wells. Finally, insights gained through real-time analytics helped consider options to mitigate poor weight transfer on future wells.

Positive Displacement Motors (PDM) offer economic efficiencies for unconventional operators, but there are limitations with weight transfer to the drill bit, especially in extended laterals. The requirement to slide during directional trajectory changes may induce premature drillstring failure by causing severe buckling and stress.

Directional control in the subject well deviated significantly from the plan which was believed to be a major contributor to the poor weight transfer to the bit, known as weight stacking. With the use of real-time engineering models and analytics apps, the operator was able to monitor the loads placed throughout the drillstring. Buckling analysis predicted when the drillstring entered either sinusoidal or helical buckling. Broomstick plots for hookload and surface torque provided information on friction factors and the health of the wellbore. von Mises stress was monitored to compare the combined stress load to drillpipe yield strength along with other component stresses including axial, bending, torsional, and various shear stresses. These applications integrated with real-time monitoring identified long periods while sliding in the latter half of the lateral where erroneously high weight on bit (WOB) at the surface indicated weight stacking on the drillpipe. They also revealed extensive buckling that caused poor weight transfer to the bit, which reduced rate of penetration (ROP) and increased drilling time.

It is important to note that the entire drillstring had been inspected (DS-1 Cat-4) prior to drilling the subject well and, therefore, would normally not have been inspected again after the subject well. The operator chose to re-inspect 21 joints that were exposed to the most severe buckling while drilling the lateral, specifically when stacking weight on the drillstring in an attempt to increase PDM differential pressure and ROP during slide drilling. Results showed 71% of joints were damaged and required repair. Of the damaged joints, 20% were so severely damaged that rigsite repair was not possible.

This paper shows how the use of real-time analytics can help monitor drillstring buckling and stresses and detect harmful patterns such as stacking weight to improve real-time decisions to mitigate damage. This information can also help plan subsequent wells and drillstring designs.