How does the process of compaction affect porosity?

Compaction affects porosity by reducing the volume of pore spaces that exist between sediment grains as these grains are squeezed together under the weight of overlying materials. This process occurs predominantly in sediments and sedimentary rocks, where overburden pressure compresses the sediment. As the grains settle closer together, the empty spaces that contribute to porosity become smaller, leading to a decrease in the overall porosity of the material.

This phenomenon is especially significant in geological contexts where sediment layers accumulate over time. The deeper the sediments are buried, the greater the compaction, which further diminishes porosity. In many sedimentary environments, as compaction occurs, the original open spaces that allowed fluids to move through the rock are reduced, potentially leading to a decrease in the ability of the rock to store or transmit water, oil, or gas.