A NEW METHOD OF DETERMINING POROSITY IN SEDIMENTARY ROCKS

Determination of porosity in sedimentary rocks is central to the evaluation of potential storage volume for hydrocarbons. We are evaluating porosity in sandstones using the methodology of crystal size distribution (CSD) theory proposed by Marsh (1988). Although this theory has been used to measure the number of crystals per unit size range per unit volume, our results show that it can easily be applied to measuring the porosity in thin sections of sandstones. In this new method of measuring pores in thin sections, we collected data on number of pores per unit size per unit area first, and then converted it to per unit volume using the procedure suggested by the CSD theory. Sum of pores per unit size per unit volume is the total pore space in the rock. In addition to providing accurate porosity measurements, this new method of measuring porosity in sedimentary rocks also provides other important information about porosity including distribution of pores as a function of depth in a drill core, percent of pores in each size range and pore types and pore geometry.