Calibration of Parameters Used in the Processing of Nuclear Magnetic Resonance Data, Acquired in Heavy- to Extraheavy-Oil Reservoirs, by Integrating Core, Production, and Conventional Log Data With Magnetic Resonance Data—Orinoco Belt, Eastern Venezuela

Abstract

Abstract Permeability, fractional porosities, irreducible water saturation and fluid viscosity calculations, derived from Nuclear Magnetic Resonance (NMR) data, are largely dependant on T2 decay rates (in NMR terminology, T2 is the time constant that characterizes the decay rate of the echo train). NMR models show that the T2 of oil is directly proportional to porosity and permeability and inversely proportional to viscosity. As oil viscosity increases, T2 decreases and the NMR signal of heavy oil may coincide with the clay bound and capillary bound water signals or even be much faster. Therefore, conventional parameters and cutoffs, used in the calculations of petrophysical properties, generally cause underestimation of porosity and permeability. By integrating core, production and conventional log data with NMR data it will be able to determine appropriate parameters and cutoffs and also generate a model to be used in the calculations of petrophysical properties from NMR data. The correct parameters, cutoffs and generated model can later be used to process NMR data from other wells where core and or production data is not available.