In oil well stimulation operations, proppants are often used to keep fractures open after the fracturing process is complete.
If you're not familiar with fracturing, it's a process that involves pumping fluids, chemicals, and proppants into a wellbore at high pressure to create fractures in the formation and allow hydrocarbons to flow more easily toward the wellbore.
Without proppants, most of the newly created fractures will close when the surface pressure drops, and hydrocarbons will not flow toward the wellbore.
The two most commonly used proppants in the oil and gas industry are sand and ceramic.
Both materials are relatively inexpensive and strong enough to withstand downhole forces without breaking.
What is the mesh size of proppants?
Different proppant sizes are used depending on the formation's requirements.
Larger proppants generally have better conductivity but are more prone to breaking, which can cause partial closure of fractures.
Proppants are measured by mesh size, typically ranging from 8 to 140 mesh.
Mesh size refers to the number of holes per square inch on the screen used to measure proppant size.
The smaller the mesh size of the proppant, the larger the particle size.
Some common examples of proppant sizes are 20/40, 30/50, and 70/140 mesh.
These two numbers represent a range of proppant sizes.
How to Choose a Proppant?
Several parameters are used to determine which proppant should be used for a particular job.
Proppant Size – As we've already discussed, proppant size will determine how easily hydrocarbons flow through the fracture and into the wellbore.
Proppant Density – Denser proppants settle faster in the wellbore but can withstand higher formation stresses.
Proppant Strength – This indicates how much stress the proppant particles can withstand in the wellbore before breaking.
Proppant Shape – Generally, proppant particles with a more rounded shape can withstand higher stresses.
Purity – This indicates the amount of impurities in the proppant that may reduce fracture conductivity. These impurities are typically mostly proppant fines.
Common Proppant Types
Sand Proppants – Natural sand is commonly used as a proppant. It is inexpensive, widely available, has good conductivity, and can withstand the formation stresses of most oil wells.
Ceramic Aluminum – A synthetic proppant with better conductivity than sand and the ability to withstand higher stresses. However, it is more expensive. It is typically used in deep wells with high formation stresses.
Resin-Coated Sand – Used to prevent sand from flowing back to the surface after fracturing and to prevent fine sand from clogging small pores and reducing production. It can also withstand higher formation stresses than pure sand.