A sudden decrease in salinity of the brine flowing through sandstone causes formation damage by dispersing clay particles. This phenomenon is known as what?

A sudden decrease in salinity of the brine flowing through sandstone causes formation damage by dispersing clay particles. This phenomenon is known as what?

• A. Osmotic swelling
• B. Water sensitivity
• C. Salinity shock
• D. Clay hydration

Answer: (B)

Water sensitivity is the tendency of clay-bearing sandstone to react to changes in the salinity of injected water. When salinity falls, the electric double layer surrounding clay particles expands, reducing their cohesion and causing the clays to disperse and migrate as fines. These dispersed fines can block pore throats and reduce permeability, leading to formation damage. While osmotic swelling and clay hydration describe related clay–water interactions, the scenario of a sudden salinity drop causing dispersion and fines migration is best described as water sensitivity. Salinity shock is a broader term, but water sensitivity precisely captures this specific rock–fluid interaction.

Water sensitivity is the tendency of clay-bearing sandstone to react to changes in the salinity of injected water. When salinity falls, the electric double layer surrounding clay particles expands, reducing their cohesion and causing the clays to disperse and migrate as fines. These dispersed fines can block pore throats and reduce permeability, leading to formation damage. While osmotic swelling and clay hydration describe related clay–water interactions, the scenario of a sudden salinity drop causing dispersion and fines migration is best described as water sensitivity. Salinity shock is a broader term, but water sensitivity precisely captures this specific rock–fluid interaction.