What does the cementation exponent m represent in Archie's equation?

What does the cementation exponent m represent in Archie's equation?

• A. Cementation Exponent
• B. Tortuosity Exponent
• C. Porosity Exponent
• D. Saturation Exponent

Answer: (A)

The cementation exponent m represents how the pore geometry and connectivity of the pore space influence electrical conduction in a saturated rock. In Archie's law, rock conductivity scales with porosity raised to m, so m captures how effectively the connected pathways for electrical current form as porosity changes. If porosity drops or pore throats become less connected, conduction falls more rapidly than a simple porosity factor would suggest, and m quantifies that effect. Higher m values indicate a stronger loss of conductive pathways with decreasing porosity, while typical sands have m around 1.8–2.0, and more cemented or complex rocks often show larger values. This is why the exponent is called the cementation exponent—it reflects how grain contacts and cementation affect the connectivity of the pore network for conduction.

The cementation exponent m represents how the pore geometry and connectivity of the pore space influence electrical conduction in a saturated rock. In Archie's law, rock conductivity scales with porosity raised to m, so m captures how effectively the connected pathways for electrical current form as porosity changes. If porosity drops or pore throats become less connected, conduction falls more rapidly than a simple porosity factor would suggest, and m quantifies that effect. Higher m values indicate a stronger loss of conductive pathways with decreasing porosity, while typical sands have m around 1.8–2.0, and more cemented or complex rocks often show larger values. This is why the exponent is called the cementation exponent—it reflects how grain contacts and cementation affect the connectivity of the pore network for conduction.