Proppants

Selection of Proppants

Proppant materials are selected based on the following attributes:

• Size: The size of a proppant grain depends on the predicted size of a fracture and the requirements of the equipment used for the hydraulic fracturing job.
• Crush strength: The proppant material must be able to withstand the pressure exerted by the surrounding rocks, otherwise it will be crushed. Tiny fragments of crushed proppant grains can clog up pores, resulting in formation damage. For added expense, proppants can be coated with resin, which prevents fragments of crushed proppants from migrating and causing formation damage.
• Weight: Heavier proppants are more difficult to move through the well and fracture networks. However, they are often stronger. This attribute is usually a trade-off between strength and ease of transport down the wellbore.
• Cost: As always, economic considerations are critical when determining whether a certain proppant is worth the cost. In addition to the cost of the proppants themselves, the increased cost of getting heavier proppants to the fractures (by increasing flow rates or viscosity) needs to be taken into account.

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Ceramic Proppant

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Resin-Coated Proppant

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Sand Proppant

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Typical attributes of some common proppants are shown in the table below.

Material	Strength	Crush Strength	Weight
Sand	Weak	6,000 PSI	2.6
Kiln Fired Clay	Medium	10,000 PSI	2.7
Bauxite	Strong	20,000 PSI	3.6

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Images: “Ceramic Proppant” by Top Energy Training; “Resin-coated Proppant” by Top Energy Training; “Sand Proppant” by Top Energy Training