The grain size of proppants falls into 11 specifications. The combination of standard sieves used in sieve analysis is as Table 1. The quality of sample fallen into grain size specifications is not less than 90% of its sum; the quality of sample smaller than the lower limit of grain size specifications is not more than 2%, and greater than aperture of top sieve is not more than 0.10% of its sum; the quality fallen on sieve of lower limit of proppant grain size specifications is more than 10 of its sum.

 Table 1: Proppant Grain Size Specifications and Combination of Test Standard Sieves

Sphericity and Roundness

Sphericity and roundness of natural quartz sand is not lower than 0.6.

Sphericity and roundness of man-made sintered ceramic proppants is not lower than 0.8.

4.3 Acid Solubility

   Allowable value of acid solubility for all proppants of different grain size specifications is as Table 2, which is also applied to acid solubility index of natural quartz sand and man-made sintered ceramic proppants.

Table 2: The Index of Acid Solubility for Proppants

The turbidity of proppants is not more than 100 FTU.

 The ruled size and scope crush case is used to test the crush resistance of ceramic proppants. It should be done the tests of 52 MPa and 69 MPa at simulating closure stress. If need of contrasting performances of ceramic proppants, not less than two, and as for the demand of performance contrast, the tests of 86 MPa and 100 MPa should be done at stimulating closure stress.