Texas Tech University Petroleum Engineering Department
TTU Home College of Engineering Petroleum Engineering Department MRI-PAC

Magnetic Resonance Imaging Lab(MRI-PAC)

The Charter

The MRI-PAC is a research center dedicated to the application of MRI and NMR to problems in engineering and science. Although the principal focus is on applications in petrophysics and petroleum engineering, the Center’s charter approves its use for interdisciplinary research where it can make significant contributions. The Magnetic Resonance Imaging Petrophysical Application Center (MRI-PAC) originated as a donation from a consortium of oil and service companies of $3.5M of capital equipment and site preparation.

The Technology

Over the last several decades new NMR techniques have been developed to study and characterize the properties and dynamics of complex fluids, emulsions, liquid structures and properties of the porous media which these fluids may occupy. These techniques have found application in medical, biological, chemical and most recently, energy sciences and industries.


These new applications are based primarily on the transient time responses in pulsed NMR rather than on the spectroscopic detail so familiar to chemists. Instead of chemical shift, the fundamental parameters considered are the relaxation times T1, T2, T2*, and the diffusion coefficients D. Theory and practice has succeeded in relating these parameters to the sizes of molecular aggregates and to the common transport properties of viscosity, diffusion, and thermal conductivity. Because the NMR parameters are also understood at the level of quantum mechanics as well as molecular dynamics, these correlations allow a deep and detailed understanding of fluid processes across microscopic and macroscopic dimensions.


The continuing growth of NMR applications derive from its fundamental experimental advantages. Since NMR interacts with the sample through magnetic fields alone, properties deep within a sample can be measured without contact or interference. Measurements at extremes of pressure or temperature become plausible; and because the energies of the NMR interaction are so small the technique does not perturb the processes being measured. These advantages give MRI – the imaging extension of NMR its power.


The research potential of NMR and MRI are indicated by the growth of research publications involving them. Considering that NMR is over 50 years old, the continuing growth of 5% per year is remarkable. It is worth noting that MRI publications have tripled in the last decade and that the 2003 Nobel Prize for medicine and the 2002 Nobel Prize for Chemistry was for research in NMR.

 graph

It is hazardous to predict the future course of science but a fairly reliable guide is that science is ultimately driven by the perceived and real needs of society. It can be argued that, for today and the foreseeable future, the highest concerns of society are healthcare and energy, and that research in these areas will continue to grow. NMR and MRI are major experimental tools in both these venues and should find growing application and development.

Facilities

The Center is housed in a secure 1800 sq. ft. laboratory in the Dept. of Petroleum Engineering. Its two primary instruments are a 2.0T Varian Inova Imager and a low-field (2Mhz proton) Maran Resonance Spectrometer. Another Maran system specialized for high pressure has recently been obtained. This combination of low field systems and high field MRI make this facility unique to all engineering colleges in the U.S..

 MRI Pac

The high field imaging machine uses a horizontal Oxford Superconducting Magnet with a 43cm clear bore. The ADC front-end has a fast 0.5 MHz bandwidth that is 5x faster than the standard medical imager. Moreover, the machine has been upgraded with state-of-the-art quadrature birdcage rf coils and chemical-shift, diffusion, backplane reconstruction and other specialty pulse sequences. These modifications make the instrument ideal for advanced imaging of materials, flows and the visualization of structures at 100 micron resolution. Although an imaging system, this scanner can be also used as a very large volume spectrometer. This allows the use of large specialized NMR probes enabling experiments at the extremes of pressure and temperature – experiments not possible in common NMR spectrometers.

MRI Pac

Associated with the imager are Temco fiberglass Hassler sleeve corebarrels for running corefloods and a variety of supporting equipment, including Quizzix and Isco constant pressure/constant flow pumps and various metallic pressure vessels and Hassler sleeve cells for coreplugs and whole core. There is a Ruska coreplug porosimeter and a Phoenix Precision Helium porosimeter. Large volume NMR probes are available for 13C, F, D as well as various geometry 1H probes. Current temperature control uses an FTS Airjet.

MRI Pac

The low field 2 MHz Resonance Instruments Maran 2 spectrometer has gradient capability along the z-axis. This is the standard apparatus used to support NMR log interpretation with NMR relaxation measurements on one-inch diameter samples. These low field instruments are beginning to be used to study bone and other biological samples as well as colloidal suspensions and emulsions. There is in addition a non-proton heat exchanger system for measurements at elevated (reservoir) temperatures and a plastic NMR cell for live fluids at up to 4000 psig pressure. The center recently acquired a second low field system as a gift from Halliburton. This system is capable of much higher pressure measurements on larger samples.

MRI Pac

The Center has excellent supporting equipment; test and measurement electronics, computers and a Luxtron fluoroptic thermometer, which works without interference in strong rf and magnetic fields. The Center uses a Bartington MS-2 magnetic susceptibility instrument and an APS fluxgate magnetometer to characterize its samples.

The Petroleum Engineering Department provides excellent supporting facilities. Included in this is a full PVT lab with a rolling ball viscometer for viscosity measurements at reservoir conditions.

Other Facilities

The Petroleum Engineering Department provides standard supporting facilities. Included in this is a full Ruska PVT lab with a rolling ball viscometer for viscosity measurements at reservoir conditions.

The Center has Temco fiberglass Hassler sleeve corebarrels for running corefloods in the Varian imager. We have a variety of supporting equipment, including Quizzix and Isco constant pressure/constant flow pumps and various metallic pressure vessels and Hassler sleeve cells for coreplugs and whole core. We have a Ruska coreplug porosimeter and a Phoenix Precision whole-core porosimeter.