Lacunarity of geophysical well logs in the Cantarell oil field, Gulf of Mexico

Abstract

Lacunarity and fractal variations in geophysical well logs are associated with stratigraphic and petrophysical properties of the naturally fractured Cantarell field in the Gulf of Mexico. Neutron porosity (NPHI), density (RHOB, DRHO, PEF), resistivity (LLD, LLS, MSFL), natural radioactivity (GR, CGR, URAN, POTA, THOR) and caliper (CALI) logs are studied. The resistivity logs yielded remarkably high lacunarity values, especially in the hydrocarbon source- and reservoir rocks. Lacunarity Λ was found to depend on the resolution and radial depth of penetration of the logging method. It systematically increased in the following order: Λ(RHOB) < Λ(CALI) < Λ(PEF) < Λ(URAN) < Λ(GR) < Λ(NPHI) < Λ(POTA) < Λ(CGR) < Λ(THOR) < Λ(MSFL) < Λ(DRHO) < Λ(LLS) < Λ(LLD).