Question

The coefficient of permeability by Packer for length in the range 10r > L ≥r  test is given by ________

(a) \(k=\frac{q}{2πh}log_{10} \frac{L}{r} \)

(b) \(k=\frac{q}{2πLh}log_{10} \frac{L}{r} \)

(c) \(k=\frac{q}{2Lh}log_{10} \frac{L}{r} \)

(d) \(k=\frac{q}{2πLh}sinh^{-1}\frac{L}{2r} \)

I had been asked this question in a national level competition.

This question is from Well Hydraulics topic in section Well Hydraulics of Geotechnical Engineering I

Answer 1

The correct option is (d) \(k=\frac{q}{2πLh}sinh^{-1}\frac{L}{2r} \)

For explanation I would say: The coefficient of permeability k for 10r > L ≥r is given by,

\(k=\frac{q}{2πLh}sinh^{-1}\frac{L}{2r} \)

where, q=discharge or constant rate of flow

r=radius of casing

h=differential head of water

L=length of portion of hole tested.