Applications of Frac Sand and Proppants
Hydraulic fracturing is a technique used in the oil and gas industry to enhance the production of oil and/or natural gas from wells. This method employs hydraulic pressure to fracture the producing formation; proppants are then pumped into the well along with the fracturing fluid to keep the fractures propped open, allowing natural gas or crude oil to flow out of the well. The size, shape, and mechanical strength of the proppant affect the integrity of the newly formed fractures and, consequently, the flow rate of oil and gas from the well.
Characteristics of Frac Sand and Proppants
A wide range of materials is used for proppants, extending from naturally occurring sand grains and resin-coated sand to high-strength ceramic materials and resin-coated ceramics.
Quality Control
Quality control for proppants is primarily outlined in ISO 13503-2 (1), a standard that superseded earlier API standards RP 56, 58, and 60. Among other tests, this standard requires testing for size, shape, and compressive strength.
Size
The particle size range of proppants is critical. Typical proppant size ranges generally fall between 8 and 140 mesh (106 µm – 2.36 mm)-for example, 16–30 mesh (600 µm – 1180 µm), 20–40 mesh (420 µm – 840 µm), 30–50 mesh (300 µm – 600 µm), 40–70 mesh (212 µm – 420 µm), or 70–140 mesh (106 µm – 212 µm). When describing frac sand, the size is often referred to simply by the sieve designation, such as "20/40 mesh sand."
Shape
The shape of the proppant is crucial, as both shape and size influence the final permeability of the fracture. An excessively wide range of particle sizes and shapes can lead to tight packing, thereby reducing permeability and fracture conductivity. Conversely, controlling the particle size range and prioritizing spherical particles can enhance conductivity.