Final answer:
Porosity measurements from downhole logging provide information about the open spaces within rock formations and have various applications in geology.
Step-by-step explanation:
Porosity measurements from downhole logging provide valuable information about the open or void spaces within rock formations. Porosity is expressed as a percentage of the volume of open space compared to the total rock volume. These measurements are important for various purposes, such as determining the geologic history of the sediment, locating fluids (water or oil), and assessing the stability of sedimentary rock formations.