A better understanding of the transport properties of geothermal reservoirs will enable us to improve their energy recovery. With this in mind, we determine pore-body and pore-throat size distributions of The Geysers, which is the largest operating geothermal resource. We determine the former by modeling water adsorption and desorption, and the latter by investigating capillary pressure measurements for The Geysers samples. Our study is based on the acyclic pore model, which is physically representative of the matrix porosity. The matrix of rock is the finer grained mass that acts as a framework for larger grains. An integrated analysis of the petrophysical measurements helps us characterize the connected pore system of the formation more accurately because such measurements are sensitive to different aspects of the pore topology. (C) 2016 Elsevier Ltd. All rights reserved.