Direct Detection of Hydrocarbon Displacement in a Model Porous Soil with Magnetic Resonance Imaging

Cheng, Yuesheng; MacMillan, Bryce; MacGregor, Rod P.; Balcom, Bruce J.

doi:10.1021/ac048540s

Cited by 10 publications

(10 citation statements)

References 22 publications

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“…39,[99][100][101][102] Furthermore, MRI enables the direct observation of fluid transport through a core plug, notably in studies of forced displacement of oil. 103 Low field profiling has been used to monitor oil recovery in short core plugs where nonuniform liquid distributions are observed due to capillary end effects and viscous instabilities. 35,104 The spatial dimension allows the oil saturation to be determined directly in the middle of the core plug, thereby ignoring the influence of such end effects that would dominate conventional estimates of saturation from bulk effluent analysis.…”

Section: Imagingmentioning

confidence: 99%

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Contributed Review: Nuclear magnetic resonance core analysis at 0.3 T

Mitchell

Fordham

2014

Review of Scientific Instruments

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Nuclear magnetic resonance (NMR) provides a powerful toolbox for petrophysical characterization of reservoir core plugs and fluids in the laboratory. Previously, there has been considerable focus on low field magnet technology for well log calibration. Now there is renewed interest in the study of reservoir samples using stronger magnets to complement these standard NMR measurements. Here, the capabilities of an imaging magnet with a field strength of 0.3 T (corresponding to 12.9 MHz for proton) are reviewed in the context of reservoir core analysis. Quantitative estimates of porosity (saturation) and pore size distributions are obtained under favorable conditions (e.g., in carbonates), with the added advantage of multidimensional imaging, detection of lower gyromagnetic ratio nuclei, and short probe recovery times that make the system suitable for shale studies. Intermediate field instruments provide quantitative porosity maps of rock plugs that cannot be obtained using high field medical scanners due to the field-dependent susceptibility contrast in the porous medium. Example data are presented that highlight the potential applications of an intermediate field imaging instrument as a complement to low field instruments in core analysis and for materials science studies in general.

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Section: Imagingmentioning

confidence: 99%

“…Phosphorous is used in clinical MRI 120 and could be an alternative to sodium for detection of the aqueous phase. 13 C (ν 0 = 3.2 MHz) may be used as a robust indicator of oil or miscible gas, 103 including supercritical CO 2 .…”

Section: B Other Nucleimentioning

confidence: 99%

Contributed Review: Nuclear magnetic resonance core analysis at 0.3 T

Mitchell

Fordham

2014

Review of Scientific Instruments

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“…Lacking magnetic field gradients at the k-space origin, the imaging experiment will not suffer significant diffusive attenuation [5]. In previous work, SE-SPI has proven very successful in cases where the inherent S/N is poor, such as natural abundance 13 C imaging [6], 13 C gas phase imaging [7] and high resolution thin film imaging [8]. In addition, as a pure phase encoding technique, SE-SPI will be largely immune to image distortion due to susceptibility variation and paramagnetic impurities in porous media.…”

Section: Introductionmentioning

confidence: 99%

Spin echo SPI methods for quantitative analysis of fluids in porous media

Li¹,

Han²,

Balcom³

2009

Journal of Magnetic Resonance

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Fluid density imaging is highly desirable in a wide variety of porous media measurements. The SPRITE class of MRI methods has proven to be robust and general in their ability to generate density images in porous media, however the short encoding times required, with correspondingly high magnetic field gradient strengths and filter widths, and low flip angle RF pulses, yield sub-optimal S/N images, especially at low static field strength. This paper explores two implementations of pure phase encode spin echo 1D imaging, with application to a proposed new petroleum reservoir core analysis measurement. In the first implementation of the pulse sequence, we modify the spin echo single point imaging (SE-SPI) technique to acquire the k-space origin data point, with a near zero evolution time, from the free induction decay (FID) following a 90 degrees excitation pulse. Subsequent k-space data points are acquired by separately phase encoding individual echoes in a multi-echo acquisition. T(2) attenuation of the echo train yields an image convolution which causes blurring. The T(2) blur effect is moderate for porous media with T(2) lifetime distributions longer than 5 ms. As a robust, high S/N, and fast 1D imaging method, this method will be highly complementary to SPRITE techniques for the quantitative analysis of fluid content in porous media. In the second implementation of the SE-SPI pulse sequence, modification of the basic measurement permits fast determination of spatially resolved T(2) distributions in porous media through separately phase encoding each echo in a multi-echo CPMG pulse train. An individual T(2) weighted image may be acquired from each echo. The echo time (TE) of each T(2) weighted image may be reduced to 500 micros or less. These profiles can be fit to extract a T(2) distribution from each pixel employing a variety of standard inverse Laplace transform methods. Fluid content 1D images are produced as an essential by product of determining the spatially resolved T(2) distribution. These 1D images do not suffer from a T(2) related blurring. The above SE-SPI measurements are combined to generate 1D images of the local saturation and T(2) distribution as a function of saturation, upon centrifugation of petroleum reservoir core samples. The logarithm mean T(2) is observed to shift linearly with water saturation. This new reservoir core analysis measurement may provide a valuable calibration of the Coates equation for irreducible water saturation, which has been widely implemented in NMR well logging measurements.

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“…This is achieved either by doping the fluid phase with paramagnetic ions such as Cu 2+ , Mn 2+ , and Ni 2+ [6][7][8], or by using deuterated water, fluorinated oil or natural abundance 13 C oil as fluids [9][10][11]. However, the underlying relaxation time distributions of water and oil in the porous media, which may also be naturally short lived, makes the use of paramagnetic ions problematic.…”

Section: Introductionmentioning

confidence: 99%

“…The use of deuterated water or fluorinated oils are less attractive because of issues related to cost, safety and departure from natural conditions. 13 C due to its low natural abundance and reduced sensitivity, permits only limited applications [11,12].…”

Section: Introductionmentioning

confidence: 99%