Download The quantity of water contained in rocks depends upon porosity

The quantity of water contained in rocks depends upon porosity. We
can define:


Total porosity
Effective porosity
Total porosity
Total porosity is the ratio of the voids volume in the rocks to the total
volume of the rock. It is a dimensionless quality expressed as a
percentage.
We differenciate between primary and secondary porosity. Primary
porosity, created during the deposition of the sediment, is an
intergranular type. Its magnitude depends on the degree of sorting
and the shape of the grains. It does not depend on the grain size.
Primary porosity, which is mainly observed in clastic rocks, generally
decreases in time due to the effects of cementation and compaction.
Secondary porosity includes vuggy porosity acquired as a result of
dissolution, fracture porosity and intergranular porosity, due to
weathering.
Effective porosity
Pores, to allow the circulation of fluid should be connected. Effective
porosity can be defined as:
It can be much lower than the total porosity when the pores in a rock
are not connected ( pumice stone) or when the size of the pores is
such that the fluids cannot circulate (silts) or even when a part of the