proppants

Proppants are solid granular materials used in hydraulic fracturing to keep fractures in reservoir rocks open after the pumping pressure is released. By propping the fracture faces apart, they create conductive channels that allow oil, gas, or other fluids to flow back to the wellbore.

The most common proppants are silica sand, resin-coated proppants, and ceramic proppants. Silica sand is inexpensive and widely available, making it a default choice in many plays. Resin-coated proppants have a polymer coating that reduces fines production and can improve conductivity in some formations. Ceramic proppants are engineered from aluminosilicate materials and generally offer higher crush resistance and strength, making them suitable for high-closure-stress or high-temperature reservoirs. Other specialized materials exist but are used less frequently.

Key properties of proppants include particle size distribution, roundness and sphericity, and crush resistance. Size is typically specified by mesh designations (for example, 20/40 or 40/70), which influence fracture width and conductivity. Roundness and sphericity affect packing and flow through fractures. Crush resistance, often expressed as closure stress capacity, determines whether proppants will remain intact under the formation’s stress. Permeability of the proppant pack and its density also influence overall fracture conductivity.

Selection depends on formation characteristics such as closure stress, permeability, temperature, and chemical environment, as well as cost considerations. In low-stress reservoirs, sand proppants may suffice, while high-stress or corrosive environments may require ceramic or resin-coated options to maintain fracture conductivity over time. Proppants are a fundamental component of hydraulic fracturing design and performance analysis.