Which method is commonly used to measure porosity in sedimentary rocks?

The water absorption test is commonly used to measure porosity in sedimentary rocks because it involves assessing the amount of water a rock can absorb. This method capitalizes on the fact that the pores within the rock can retain water, and measuring the volume of water absorbed provides a direct indication of the rock's porosity.

In this test, the rock sample is typically saturated with water, and the increase in weight is measured to determine the porosity percentage. This approach is straightforward and yields immediate insights into the rock's capacity to hold fluids, making it particularly useful for evaluating reservoirs in geology and petroleum engineering.

Other methods, such as the density gradient method, involve more complex procedures and are generally used to determine the density of materials rather than directly measuring porosity. Grain size analysis can provide indirect information about potential porosity by inferring the relationship between grain size and pore space, but it does not directly quantify porosity itself. Radiometric dating, although valuable for determining the age of rocks, does not apply to measurements of porosity and is focused on isotopic analysis instead.