petrofysica

Petrophysics is the science of the physical and chemical properties of rocks and their interactions with fluids in the pore space of earth formations. In the context of hydrocarbon exploration and production, petrophysics aims to quantify properties such as porosity, permeability, saturations, mineralogy, and wettability to evaluate reservoirs. The term petrofísica is used in Spanish and Portuguese.

Key petrophysical properties include porosity (the fraction of pore space; total porosity versus effective porosity), permeability (the ease of fluid flow through the rock), and fluid saturations (fractions of rock pore space occupied by oil, water, and gas). Other important factors are capillary pressure, clay effects, wettability, and formation mechanical properties derived from sonic measurements.

Data sources include well logs (gamma ray, density, neutron, sonic, resistivity, NMR), core samples (porosity, permeability, capillary pressure, mineralogy), and formation tests. Archie's law and its extensions relate electrical resistivity to water saturation in clean rocks; NMR provides porosity and pore-size distribution estimates; resistivity measurements help delineate hydrocarbon-bearing zones.

Petrophysical analysis integrates measurements to deliver formation evaluation, reservoir characterization, and rock property models used in reserve estimation, well placement, and production planning. It supports interpretation of heterogeneity, anisotropy, and diagenetic alterations, and underpins enhanced oil recovery and waterflood design.

Practitioner roles include petrophysicists, geologists, and reservoir engineers who collaborate to build petrophysical models, quality-control data, and quantify uncertainties. The field combines geology, physics, chemistry, and engineering to translate log and core data into actionable reservoir information.