Qatif-Phi

UCS = 20849e^(–6.95 ´^Φ)

where

20849 is in psi.

6.95 is a non-dimensional constant.

This equation is derived from multistage triaxial tests on 13 limestone samples from a well in the Middle East. The core porosity range is between 4.8% and 19.7% with a 13.5% average. The reported UCS ranges between 4,900 and 22,500 psi. There is a major concern about the data set due to the test procedures and the reported UCS may not represent the actual uniaxial compressive strength of the samples.