Chapter 2 - Petrophysical Characterization of the Pore Structure of Coal

Abstract

Coalbed methane (CBM) is an important unconventional gas resource, and pore structure characterization is important for CBM reservoir evaluation. Existing methods for studying the petrophysical properties of coal have limitations on the data quality or require sample destruction. In this chapter, we present the experimental results of low-field nuclear magnetic resonance (NMR) relaxation of 12 coal samples under different water-saturated conditions. Results show that NMR characterization of porosity, pore size distribution, pore geometry, pore connectivity, and permeability of coal is reliable and better than other conventional methods. More importantly, the NMR method does not require the destruction of the coal samples and is not time-consuming. It is concluded that the NMR method should be applied for CBM reservoir analysis in the laboratory and CBM well loggings in the coalfield.