HPHT Cool Down
High temperature, high pressure wells are always demanding. One obvious challenge is to keep the mud cool. If the mud gets too hot, vital functions will crumble and the drilling will eventually have to be stopped.
The Tomax AST was called out for a deep 12 ¼” section on the Kvitebjørn (White Bear) HPHT gas field. The task was to mitigate a problematic stick’n slip tendency and thereby widen the choice of drilling parameters in order to reach TD.
With the 9 ½” XC-AST in the BHA, the torsional loading stabilized and the drilling efficiency improved. The previous BHA was pulled due to decreasing ROP. The new BHA with AST gave both faster and more steady progress.
The better efficiency meant less energy was transformed in to heat and vibration. The improvement made it possible drill ahead using only two thirds (2/3) of the input power. This caused a distinct drop in the Bottom Hole Temperature (BHT).
The client reached the desired section depth. The BHT was down by 10 deg. C at this point compared to previous projections. There was no real risk from vibrations. The achieved deep TD also eliminated an optional intermediate section.