Design, fabrication, testing and usage of magnetic resonance and magnetic resonance imaging compatible metallic core holders
University of New Brunswick
Magnetic Resonance (MR) and Magnetic Resonance Imaging (MRI) are powerful tools for non-invasive studies of fluid content and fluid behavior in petroleum reservoir core plugs. Core analysis MR/MRI studies should be undertaken with the reservoir pressure and temperature, as high as 20000 psi and 200 ˚C, replicated in a core holder. Metal core holders are generally favored in the core analysis industry due to their superior safety performance and ease of temperature regulation. In this thesis, three prototype MR/MRI compatible metallic core holders were designed, fabricated, tested and used for petroleum studies. The thesis research comprised two parts. The first was MR/MRI compatible metallic core holder development; the second was methane hydrate studies as one specific very advantageous use of the new core holders. The core holder development process, Part I of the thesis, consisted of four main steps as follows. Step 1 was designing, fabricating and integrating different components of the MR/MRI compatible metallic core holders. Step 2 involved calibrating, testing and correcting the electrical and mechanical performance of the metal core holders. Step 3 was the testing of the core holder with representative petroleum processes. Step 4 was prototype evaluation and of an improved prototype. All three prototypes, fabricated from non-magnetic superalloys, accommodated standard core plug samples, 1.5” in diameter and 2” in length, for MR/MRI core analysis measurements at high pressures and elevated temperatures. These superalloy core holders, featured high tensile strength and low electrical conductivity. The third prototype was pressure tested to 15000 psi. The three prototypes incorporated the RF probe, to excite and detect the MR signal, inside the metal case, which functioned as a RF shield. In part II of this thesis, methane hydrate formation and dissociation processes were investigated employing the third prototype core holder. Hydrate formation occurred in water-saturated sand at 1500 psi and 4 °C. A hydrate-bearing sand pack, with 96% initial hydrate saturation, underwent dissociation by depressurization at 290 psi and 4 °C.