The GeoSpec is the industry standard NMR core analyzer, with installations in nearly every key oil producer and SCAL laboratory around the world.
Oxford-Instruments’ partnership with Green Imaging Technologies guarantees full hardware and software integration which makes it possible for any core analysis laboratory to acquire detailed NMR core analysis results without the need for an in-house NMR expert.
The GeoSpec range presently comprises instrument models operating at 2, 12 and 20MHz.
The 2 MHz models are the industry standard for regular measurements of relaxation distributions, leading to predicition of petrophysical parameters such as porosity, T2 cutoff, and free and bound fluid determinations. These instruments work at 2 MHz to reduce artifacts caused by ferromagnetic material in the samples and to imitate the operation of the NMR logging tools.
All 2 MHz GeoSpec models are fitted with Q-Sense, Oxford-Instruments innovative technology for enhanced signal-to-noise and ultra-short echo times. Both these features are vital for accurate measurements on shales and tight rocks.
The 2 MHz GeoSpec models are available in three different magnet sizes to house cores from 1/2” to 6” diameter.
The higher field (12 and 20 MHz) GeoSpec models are available for circumstances where higher sensitivity is necessary (for example, very low porosity samples), and for special applications such as Magnetic Resonance Imaging (MRI). Maximum sample size is smaller than for the 2 MHz models, with the 12 MHz model able to house samples up to 53 mm (2”) diameter and the 20 MHz model up to 26 mm (1”).
Core Analysis Measurements
Routine core analysis measurements possible with GeoSpec analyzers include the following:
- Well log calibration
- Bulk volume Irreducible (BVI)
- Pore size distribution
- Free Fluid Index (EFI)
- Total porosity
- Clay Bound Water (CBW)
With the inclusion of extra hardware and software options, the GeoSpec range can handle more advanced research applications. By adding an accessory called Pulsed Field Gradients (pfg) to the NMR instrument, it becomes possible to perform measurements based on the flow, diffusion, or distribution of the fluids within the core sample. This allows us to conduct measurements to examine, for example, fluid typing and fluid distribution.
Patented software allows 2D data maps to be designed to assist with fluid typing, and other patented software produces spatially-dependent T2 distributions from “slices” along the core length. It is also possible to perform the capillary pressure measurements in virtually a quarter of the time taken by the traditional centrifuge capillary pressure measurement, and with many more points on the capillary pressure curve.
Overburden Studies Using the P5 Cell
Nuclear Magnetic Resonance (NMR) is a beneficial tool for both regular core analysis and SCAL. Majority of measurements are performed at ambient temperature and pressure, but it is becoming increasingly important to conduct measurements at as close to reservoir conditions as possible.
The P5 Cell, exclusive to the GeoSpec range of NMR rock core analyzers and available for 2 and 12 MHz models, allows users to achieve this. Designed and constructed with a focus on usability and performance, the cell allows users to pressurize samples with up to 5,000 psi of confining pressure, at up to 100 ºC.