Eliminate casing run

While some fields of the basin are considered low risk for casing while drilling, others present more challenges, such as the D129 Lacustrine Formation. This is a highly interbedded formation with hard impact and abrasive layers with UCS as high as 40,000 psi. Lithology is mainly sandstone and claystone with inclusions of igneous rock (tuff and basalt). The operator needed to drill a second run of the production section using casing while drilling.

Use casing while drilling

The proposal included a bit specially designed for casing-while-drilling applications. The design objectives were a more efficient cutting action to enable higher ROP with excellent dynamic stability for lower shock and vibration and lower surface torque. Because this bit would be used on the final section of the well, it did not require being drillable. It would be attached to the sub connecting it to the casing string.

Increase drilling speed and depth

The entire section was successfully drilled, despite the high UCS and heavy-abrasion and -impact D129 Formation. ROP was nearly five times higher than expected—19.45 m/h vs. 4 m/h. The performance excellence enabled the operator to drill 41 m deeper than the plan and set the casing at 2,211 m.