Drilling & Well Completion Flashcards

What is the purpose of 'reaming' while running casing to bottom?

Answer: Work the casing past tight spots or ledges in the borehole by rotating and reciprocating

Reaming involves rotating and reciprocating the casing string to break down tight spots or bridges that resist casing advancement to bottom.

In a managed pressure drilling (MPD) operation, which equipment is used to apply backpressure to the annulus?

Answer: Rotating control device (RCD) combined with a choke manifold

An RCD seals the rotating drillstring at the wellhead, and the backpressure choke controls annular pressure precisely in MPD operations.

What does 'swabbing' refer to in well operations and what hazard does it create?

Answer: Pulling the drillstring or tubing too fast, reducing annular pressure below formation pressure and potentially inducing a kick

Swabbing occurs when upward pipe movement creates a piston effect that temporarily reduces hydrostatic pressure, potentially pulling formation fluids into the wellbore.

Which type of drill bit is most suitable for drilling hard, abrasive formations such as quartzite or chert?

Answer: Diamond impregnated bit

Diamond impregnated bits use diamonds embedded throughout the bit body matrix, providing superior abrasion resistance for very hard, abrasive formations.

What is 'wellbore breathing' and how does it differ from a gas kick?

Answer: Wellbore breathing is ballooning caused by elastic formation response during circulation/shut-in cycles; gas kicks show continuous pit gain and increasing shut-in pressures

Wellbore breathing (ballooning) results from fractures opening during circulation and closing on shut-in, causing reversible pit changes without the escalating shut-in pressures seen in true kicks.

In well cementing, what is the role of a 'centralizer' on the casing string?

Answer: Center the casing in the borehole to promote uniform cement distribution around the annulus

Centralizers keep the casing away from the borehole wall, ensuring an even annular space for cement flow and reducing channeling on the low side.

What is the purpose of 'squeeze cementing' after primary cementing?

Answer: Force cement slurry under pressure into voids, channels, or perforations to repair an inadequate primary cement job

Squeeze cementing remedially places cement under pressure into deficient areas of a primary cement job to restore zonal isolation.