Magnetic Resonance Imaging of Porosity Heterogeneity in Bioturbated Sandstone from the White Rose Reservoir, Atlantic Canada

The determination of porosity heterogeneity within hydrocarbon reservoirs is important because cost-effective, efficient production of hydrocarbons depends on accurate knowledge of reserve estimates, and hydrocarbon distribution. A new magnetic resonance imaging (MRI) technique, based on the conical SPRITE (Single-Point Ramped Imaging with T1 Enhancement) MRI method is capable of revealing the three-dimensional geometry of porosity distribution in core samples taken from reservoir rocks. Porosity heterogeneity at the core scale is difficult to assess by conventional petrophysical methods. Conventional MRI methods also fail because of complications associated with the multi-exponential nature of spin-spin relaxation time decay and restrictions on the minimal echo time. The SPRITE MRI technique allows direct quantitative measurements of porosity and imaging of samples with short MR signal lifetimes. We illustrate the application of this method to two core samples from the White Rose reservoir: one containing shell fragments and the other fine grained and massive in texture. The data presented in this paper show the potential of the conical SPRITE MRI technique as a tool for porosity heterogeneity evaluation by application of the method to core plugs taken from sandstone reservoir rocks of the White Rose oilfield, located in offshore Newfoundland. The results show that the MRI technique can significantly enhance petrophysical studies on reservoir rocks by providing: 1) direct and non-destructive visualization of three-dimensional data required to model the porous network; 2) spatially resolved porosity throughout the core sample, which allow reveals the porosity heterogeneity and will result in better understanding of reservoir quality.