The Effect of Temperature on Estimating Free Fluid Index FFI by Nuclear Magnetic Resonance Measurement: Phase 1 Study

Abstract

Abstract Since the initial introduction of Nuclear Magnetic Resonance (NMR) Technology into the oil and gas industry as a lithology independent porosity measurement technique, NMR well logging has been providing various valuable Petrophysical reservoir properties, such as porosity, permeability index, pore size distribution, and fluid typing, etc. To increase the reliability of these NMR log data interpretation, core-log integration, combining log and laboratory data, is necessary. For example, T2 cutoff values which determine the bulk volume of movable fluid (BVM) from NMR log data are determined from laboratory NMR measurement since it requires the measurements at 2 different saturation levels which is not possible at the reservoir with current technology. Unlike NMR logging in the field, however, most of laboratory NMR measurements are conducted at room temperature and pressure. Until recently, the temperature effect on NMR relaxation data is considered to be minimal since the surface relaxation is the dominant proton spin relaxation mechanism within confined porous media, such as reservoir rock. There have been a few experimental works during the early period of NMR technology application in well logging shows minimal temperature effect on that in reservoir rocks. Recently, this phenomena has been re-investigated and been shown there is non-negligible temperature effect on the shift of NMR relaxation time. In the current work, the NMR T2cutoff values at various temperatures for 6 carbonate reservoir rocks with multipore system have been measured. Upon the verification of temperature dependence of NMR T2 cutoff values for reservoir rocks, further investigation of identifying elements that cause this phenomena has been initiated.