Percentage retention describes:

• A. The proportion of formation particles retained by the screen
• B. The proportion of water recovered through the screen
• C. The length of the screen retained in the borehole
• D. The rate at which the screen clogs

Answer: (A)

Percentage retention is about how well the screen holds back formation solids. It describes the portion of formation particles that are trapped or kept by the screen rather than passing through into the borehole. This concept matters because the screen’s slot size or mesh determines how many solids are retained, balancing filtration with fluid flow. It isn’t about how much water is recovered, how long the screen is, or how quickly the screen clogs.