Classification of proppant materials

The materials commonly used as proppants can be grouped into three main categories, listed in Table 10.25. The first proppant material used was rounded silica sand mined from glacial deposits. This material was initially selected owing to both its wide availability near production wells and its low cost, but since the early days several other industrial materials have been selected and used as proppants, and today we observe the increased use of synthetic materials, especially sintered and fused ceramics. The main impetus in focusing on ceramics was driven by the fact that ceramic materials offer suitable properties for use in modern deep wells today. 

TaMe 10.24. Critical properties for proppants Critical properties Description 

A series of crushing resistance tests consists in determining the stress at which the proppant material shows excessive generation of fines. Tests are conducted on samples that have been sieved. Four specific stress levels (i.e., 7.5,10,12.5, and 15 ksi) are used in the recommended practice (see API RP-61). 

The bulk density corresponds to the mass of proppants that fill a unit volume and includes both proppant and porosity void volume. 

Insures prop of cracks and avoids the collapse of cap rock if crushing strength is above the lithostatic pressure at the given depth. 

---