Permeability of rocks.pdf

A college level presentation on the topic PERMEABILITY OF ROCKS which comes under Mining engineering

1. PERMEABILITY OF
ROCKS

2. Permeability
The permeability of rock is a measure of the ease
with which the rock will permit the passage of fluids.
The fundamental physical law which governs this is
the Navier-Stokes equation.
We assume the flow of fluids in rock as laminar.

3. Calculation of permeability
The fluid flow through a cylindrical tube is given by the simplified
Navier-Stokes equation for laminar flow and uncompressible fluids.
The equation can be expressed as:-
About 150 years ago, Darcy carried out several experiments and then
developed an empirical formula that remains the main permeability
formula. Darcy's formula is given as:-
Where
Q= the flow rate
r = the radius of the tube (cm /m)
= the outlet fluid pressure(Pa)
= the inlet fluid pressure(Pa)
m= the dynamic viscosity of the fluid(Pa)
L= length of the tube(cm or m)
k = permeability of the sample(darcy)
A = area of the sample

4. Absolute permeability:-Absolute permeability is an ability to flow
fluid through a permeable rock when only one type of fluid is in the
rock pore spaces.
Effective permeability:-Effective permeability of rock to a fluid phase
(oil, gas, or water) in porous medium is a measure of the ability of that
phase to flow in the presence of other fluid phases.
Relative permeability:-Relative permeability is the ratio of effective
permeability of a particular fluid at a particular saturation to absolute
permeability of that fluid at total saturation. If a single fluid is present
in a rock, its relative permeability is 1.0.
There are three types of permeability:-
1.
2.
3.
Types of Permeability

5. Textural properties-
Amount, distribution and type of clays
Overburden pressure
Impurities in water
High velocity flow effects
Numerous factors affect the magnitude & or direction of the
permeability:-
a. Pore size b. Grain size distribution
c. shape of grains d. Packing of grains
FACTORS AFFECTING PERMEABILITY OF ROCKS

6. There is a general increase in permeability as grain size increases from very fine to
coarse , permeability increase as sorting progresses from very poor to well sorted.

7. SI unit for permeability is
A particle unit for permeability is darcy(d) or more
commonly the millidarcy(md).(1 darcy = )
UNIT:

8. Thank
you