Sand Control

Sand Control

A well screen must effectively prevent excessive sand movement into the well. A "sand-pumping" well risks eventual collapse and can cause significant pump wear, reducing the usability of the produced water.

In tubular wells, where the screen directly contacts the native formation, screen openings are typically sized to retain 50–90% of the formation material. For uniform fine sands, a 90% retention rate may be necessary to ensure stabilization. In graded formations (e.g., sand-gravel mixtures), 50% retention may suffice, provided proper well development techniques are applied.

For gravel-wall wells, a specially selected gravel or sand pack is placed between the screen and borehole wall to stabilize the formation. Here, screen slots are sized only to retain the gravel pack material, not the native formation. Since the artificial gravel can be 3–5 times coarser than the natural formation, much larger screen openings can be used—a significant advantage in fine-grained formations. However, as the native material becomes coarser and more graded, the benefits of gravel-wall construction diminish.

This approach balances sand control with optimal hydraulic efficiency, ensuring long-term well performance while minimizing maintenance issues.