Advances in Well Logging Techniques for Shale Reservoirs Exploration

Shale is a clay-rich, argillaceous sedimentary rock that acts as a source rock for hydrocarbon. It is also considered a potential hydrocarbon reservoir for the last few decades. Because of the fineness in grain-size and complex mineralogical character, measurement of formation reservoir properties, like porosity, saturation, and permeability in shale is complicated. Petrophysical well logging methods can play crucial role to evaluate the properties of shale reservoirs. The conventional well logging methods, like gamma ray, resistivity, density, neutron, sonic, which are used for sandstone reservoirs, provide significant information about shale properties, though the interpretation of these log data needs careful validation from other sources like core data, petrographic analysis. Every logging method has its own advantages and limitations. This chapter summarizes the applications and limitations of the standard well logging methods as well as advanced techniques like nuclear magnetic resonance in shale reservoirs. The estimation of total porosity, saturation, total organic carbon, brittleness index and velocity anisotropy are discussed in details.