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Porosity of rocks depends on such factors as:
1) mutual grains placing and grains packing;
2) form of grains;
3) amount of cement;

4) rock fracturing;
5) degree of sorting the particles forming the rock (degree of sorting
the particles is determined by means of mechanical analysis and is

expressed by the ununiformity factor);
6) availability of pores inside of mineral grains;

7) availability of caverns and washing-out channels.

1.3 Equipment, devices and materials

The following equipment and materials should be used for the
experiment: analytical balance; electric heater; the sample of the rock
(extracted and dried); the porcelain cup with paraffin; metallic or glass

bridge (special facility) and glass capacity of the 100 ml volume for

weighing the rock sample in water; fine wire or kapron thread for
hanging up the rock sample.

1.4 Procedure and calculations

To measure the imaginary (apparent) density of the rock sample

O
 the rock sample (beforehand extracted and dried under 150 C) is
r.s.
used.
1.4.1 Determine the weight of the dry rock sample in air, G , g

1
(kg).
1.4.2 Tie up the rock sample with fine (hair) wire or kapron thread

of length 15 – 16 cm.

1.4.3 Immerse the rock sample into the melted paraffin for
O
1 – 2 seconds (the temperature of paraffin must not exceed 60 C). If
there are any defects on paraffin shell they have to be removed by
repeated immersing the rock sample into paraffin.
1.4.4 Determine the weight of the rock sample covered with
paraffin in air, G , g (kg).
2
1.4.5 Determine the weight of the rock sample covered with
paraffin in the distilled water according to the scheme shown in
figure 1.1, G , g (kg).
3

6