Petrophysical Quantification of Multiple Porosities in Shale-Petroleum Reservoirs With the Use of Modified Pickett Plots

Abstract

Summary Previous petrographic work has shown that shale-petroleum reservoirs at discovery are characterized by a quad-porosity system. In this work, a petrophysical model is built that allows quantification of storage capabilities in shales through determination of adsorbed porosity (ϕads_c), organic porosity (ϕorg), inorganic porosity (ϕm), and fracture porosity (ϕ2). All these porosities are important because they provide reasonable input to physics-based numerical simulators for shale-petroleum reservoirs and thus more-realistic projections of reservoir performance and recoveries. Pattern recognition is used in a modified Pickett plot for distinguishing key shale components such as total organic carbon (TOC) and level of organic metamorphism (LOM) and to distinguish between viscous and diffusion-like flow. Results from the model compare well with laboratory data. The petrophysical model is easy to use, yet it is robust because it can handle at the same time the four porosities mentioned previously, but it can also handle simultaneously three, two, or only one of those porosities depending on the characteristics of the reservoir at a given depth. It is concluded that the petrophysical model presented in this paper constitutes a valuable tool for physics-based characterization of shale-petroleum reservoirs.