EXAMPLE 3
A protected particle was formed of a base particle having an average diameter of 100 μm. The base particle is a hollow sphere having a shell thickness of 3 μm. The interior pressure in the hollow cavity of the base particle is 14.7 psi. The density of the base particle is 0.24 g/cc and the crush strength of the base particle is 1,500 psi. The outer surface of the base particle was coated with a polyvinylalcohol coating. The outer coating thickness was 60 nm. The resulting protected particle has a crush strength of about 4,000 psi. The protected particle was configured to be pumpable into a formation with a proppant. As is evident from Examples 2 and 3, the addition of additives to the outer coating can be used to change the crush strength of the protected particle.
