A dune will form in the casing screen annulus when gravel packing what type of well?

• A. Deviated well
• B. Vertical well
• C. Horizontal well
• D. Multilateral well

Answer: (A)

Gravel packing behavior is strongly influenced by the wellbore’s orientation. In a deviated well, gravity causes the gravel to settle toward the low side of the casing screen annulus as the fluid moves, so the gravel piles up into a dune against the screen. That dune can block parts of the screen and create uneven packing, which can lead to sand-control problems. In vertical wells the packing tends to be more uniform around the screen, and in horizontal or multilateral configurations the gravity-driven dune effect is different, making dune formation less likely.