Drilling -Mechanical & Wellbore Geometry Sticking

Understand the key causes of mechanical and wellbore geometry sticking—ledges and dog-legs, key-seating, casing shoe backoff, under gauge hole, collapsed casing and tubing, cement blocks, junk—and the driller's first actions.

Learn how ledges form at rock contacts and how dog-legs bend the wellbore, then apply preventative actions and steerable systems to maintain trajectory with precise 3D control.

Understand how key seating forms when pipe rotation wears grooves in the wellbore wall, jamming the string at the keyseat during trips and dog-legs; prevent with reaming and wiper trips.

Explain casing shoe back-off when shoe joint unscrews from last casing while drilling below shoe; apply thread lock to bottom three joints, and avoid over displacing cement for liners.

Forms an under-gauge hole when drilling hard, abrasive rock wears on the bit and stabilizers, causing a hole smaller than full gauge and resistance in the underground section.

Explore how wellbore pressures exceeding collapse pressure cause collapsed casing through wear and corrosion. Use CDEx to select casing strings resisting burst, collapse, and tension, with cementing and corrosion inhibitors.

Green cement risks flash set when top is higher than predicted or circulation occurs in soft cement. Prevent by washing down above theoretical top and not relying on surface samples.

Examine how cement blocks form around the drill string and prevention steps, ream the casing shoe, limit rat-hole length, slow trips, and use fiber additives to improve cement integrity.

Prevent junk debris from entering the wellbore by maintaining good housekeeping, keeping the hole covered, and inspecting downhole equipment, slips, tong dies, and drillstring wiper rubber to avoid string jams.

Maintain circulation and apply controlled up or down jarring to free a stuck drill string. If unsuccessful, consider acid pills, and review Weatherford jars for reliable, high-load operations.

Explore the Shockforce drilling jar by NOV, a double acting hydraulic jar with upward and downward jarring, safety lock and over-pull module for reliable performance up to 30,000 psi.