First-Time Casing-While-Drilling Operation in Permafrost Eliminates Surface Casing Drillout Run | Schlumberger
Case Study
Location
Argentina, South America
Background

An operator in southern Argentina drills onshore along conventional and unconventional reservoirs, respectively. Using Allegro XCD-Pro casing-while-drilling expert service, the operator drilled an entire section through a heavily abrasive and hard impact formation with very high unconfined compressive strength (UCS) at an ROP almost five times higher than expected (19.45 m/h vs. 4 m/h). Allegro XCD-Pro service enabled drilling an additional 41 m deeper to set the casing at 2,211 m.

Products Used

Operator Multiplies ROP Using Bit Specially Developed for Casing-While-Drilling Run

Allegro XCD-Pro service produces specialized matrix bit to withstand brutal drilling environment

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.

Graph showing performance improvement with bit developed using Allegro XCD-Pro service.
Allegro XCD-Pro service enabled bit development for a run that achieved five times the ROP and footage efficiency of prior casing-while-drilling runs.
Products Used

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