Process and physical conditions of the sand cleaning system operation all have an effect on efficiency of sand cleaning. The most common items are listed and detailed below.

Temperature: increasing promotes oil-sand separation

• Decreases oil-water IFT, and increases magnitude of “-” charge on silica, decreases oil viscosity – all which promote oil-sand separation
• Recommend to change from 25° to 50°C if used

Particle Size: increasing size promotes oil-sand separation

• Small particles have higher surface area and harder to clean
• Easier to clean >100 µm particles

Scrubbing Intensity: increasing promotes oil-sand separation

• System should promote We>100:    𝑊𝑒=(𝜌𝑉^2 𝑑)/𝛾
• Increase velocity between continuous phase and particle improves oil removal

Time: longer wash time in loop improves cleaning

• Time of slurry in intense scrubbing zone (jetting unit, pipe, eductor, sand cleaning cyclone) varies from 1-3 minutes
• Total loop recirculation time is 30 minutes, typically 1-3 cycles sufficient
• Loop is tuned during commissioning – samples take periodically during initial cleaning to determine cleaning cycle duration and outlet OIW

References:

1. Rawlins, C.H. and Wang, I. 2001. “Design and Installation of a Sand-Separation and -Handling System for a Gulf of Mexico Oil Production Facility”. SPE Production and Facilities, August, pp. 134-140. https://doi.org/10.2118/72999-PA
2. Rawlins, C.H. 2019. “Enhanced Production Through Surface Facilities Sand Management.” SPE Distinguished Lecturer presentation. Link here

Next week I will cover how to integrate the system with solids handling and disposal.