1. The D coefficient can be estimated from well and rock properties
D is in 1/(Mscf/d) b is the non-Darcy flow coefficient (in 1/ft) g is the gas gravity (air = 1) All other properties in field units.
This equation assumes radial flow. It often underestimates the importance of non-Darcy flow – perhaps due to non-radial flow near the well perforations.
September 21, 2019
e-notes (c) Curtis H. Whitson

2. Correlations for Non-Darcy flow coefficient vs permeability
September 21, 2019
e-notes (c) Curtis H. Whitson