Porosity and Permeability

Question 1

ratio of pore space in a sediment or sedimentary rock to the total volume of the rock, often expressed as a percentage.

Answer 1

Porosity

Question 2

Total or absolute porosity is calculated as the ratio of pore volume (Vp) to bulk volume (Vb).

Answer 2

Total Porosity

Question 3

• pore spaces that are interconnected
• important for groundwater and petroleum analysis

Answer 3

Effective Porosity

Question 4

Originating from deposition, it can be intergranular (between framework grains), intragranular (within particles), or intercrystalline (between chemically formed crystals).

Answer 4

Primary Porosity:

Question 5

Caused by the dissolution of cements or metastable framework grains in siliciclastic sedimentary rocks, or dissolution of cements, fossils, framework crystals, etc., in chemically formed rocks.

Answer 5

Solution Porosity

Question 6

Arises from pore space in cement or among other authigenic minerals.

Answer 6

Intercrystalline Porosity:

Question 7

Occurs due to rock fracturing by tectonic forces, compaction, or desiccation.

Answer 7

Fracture Porosity

Question 8

The porosity of sedimentary rocks is influenced by various factors:

Answer 8

Depositional
Post Depositional
Initial Porosity
Diagenesis
Porosity Evolution

Question 9

This process can rearrange grain packing and reduce porosity.

Answer 9

Compaction

Question 10

can lead to a reduction in porosity.

Answer 10

Chemical dissolution

Question 11

fill pore spaces and decrease porosity.

Answer 11

Cementation

Question 12

capacity of a medium to allow the transmission of a fluid. In the case of rocks, it refers to the property that enables a fluid to flow through the interconnected pores within the rock

Answer 12

Permeability

Question 13

the rate of fluid flow through a porous rock is directly proportional to the rock’s permeability and inversely proportional to the fluid’s viscosity.

Answer 13

Darcy’s law,

Question 14

defined as the permeability unit equivalent to the passage of one cubic centimeter of fluid with a viscosity of one centipoise, flowing in one second, under a pressure differential of one atmosphere, through a porous medium with a cross-sectional area of one square centimeter and a length of one centimeter.

Answer 14

darcy

Question 15

Permeability tends to ???? with decreasing particle size. Smaller particles lead to ???? Pore diameters and ????? capillary pressures, impeding fluid flow.

Answer 15

decrease; smaller; increased

Question 16

Permeability may ???? with decreasing sorting, as variations in grain size distribution can affect the connectivity of pore spaces.

Answer 16

decrease

Question 17

Permeability may decrease with ?????? particle sphericity, possibly due to tighter packing of spherical particles, which reduces pore size.

Answer 17

increasing