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LABORATORY EXPERIMENT № 1

DETERMINATION OF THE ABSOLUTE POROSITY
FACTOR OF ROCKS

1.1 The objective of the experiment is: to determine the
imaginary (apparent) density of the rock and the absolute porosity

factor of the rock sample.

1.2 Definitions

Porosity of rock is a measure of storage capacity of a reservoir
(pore volume of the rock). It defines the ability of the rock to
contain liquids and gases. There are two types of porosity: absolute

or total and effective porosity. Quantitatively porosity is characterized
by porosity factor. In general porosity factor is the ratio of the pore

volume to the bulk volume of the rock.

The absolute porosity factor m ab.p. is the ratio of the volume of
all pores available in the rock sample V all p. to the bulk volume
of the rock sample V b.r.s. :

V all p.
m  . (1.1)
ab.p.
V
b.r.s.
Porosity factor is determined in fractions or per cents.
Taking into account that

V all p.  V  V gr. , (1.2)
b.r.s s
.
we’ll get:
V all p. V  V gr. V gr.
m   b.r.s.  1 , (1.3)
ab.p.
V V V
b.r.s. b.r.s. b.r.s.
where V is the volume of grains which form the rock.
gr.
Taking into account that the weight of the rock sample is

equal to the weight of grains forming it the equation (1.3) can be given
in the following form:

m  1 r.s , (1.4)
ab.p.
 gr.
where  is the imaginary (apparent) density of the rock sample, kg /
r.s.
3 3
m ;  gr. is the density of grains forming the rock, kg / m .

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