What are the two parts of the annulus?

What are the two parts of the annulus?

• A. The upper annulus and lower annulus
• B. The inside annulus and outside annulus
• C. The inner bore and outer bore
• D. The casing annulus and drill pipe annulus

Answer: (B)

An annulus is the ring-shaped space between two concentric cylinders in a wellbore. There are two parts: the inside annulus and the outside annulus. The inside annulus is the gap around the drill string toward the borehole’s interior, while the outside annulus is the gap toward the outer boundary (such as the borehole wall or casing) away from the center. Understanding this split helps with fluid circulation, cementing, and pressure management, since each annulus can carry fluids and experience pressures differently. The other phrasings aren’t the standard way we describe the space around the drill string: there isn’t a commonly used upper/lower division, and inner/outer bore isn’t the usual terminology for naming the two annular regions.

An annulus is the ring-shaped space between two concentric cylinders in a wellbore. There are two parts: the inside annulus and the outside annulus. The inside annulus is the gap around the drill string toward the borehole’s interior, while the outside annulus is the gap toward the outer boundary (such as the borehole wall or casing) away from the center. Understanding this split helps with fluid circulation, cementing, and pressure management, since each annulus can carry fluids and experience pressures differently. The other phrasings aren’t the standard way we describe the space around the drill string: there isn’t a commonly used upper/lower division, and inner/outer bore isn’t the usual terminology for naming the two annular regions.