Viscosity, diffusivity, relaxation time, and gas/oil ratio are important properties in the characterization of reservoirs by nuclear magnetic resonance (NMR) well logging and in prediction of production performance. For the past few years, NMR well logging has been used to estimate formation properties and hydrocarbon liquid/ vapor characterization. Previous work has shown that pure alkanes, alkane mixtures, viscosity standards, and stock tank crude oils have NMR relaxation times that vary linearly with viscosity/ temperature and diffusivity on a log-log scale. However, pure methane at some temperatures and pressures does not follow the same trend. Thus, the linear correlation may not be valid for live crude oils that contain a significant amount of methane. Therefore, the study of methane-hydrocarbon mixtures is of interest.An NMR spectrometer equipped with a high-pressure probe was used to study the relationship between NMR T 1 relaxation time and viscosity/temperature, diffusivity, and gas/oil ratio of methane-hydrocarbon mixtures. Relaxation time and diffusivity measurements of three mixtures were made: methane-n-hexane, methane-n-decane, and methane-n-hexadecane. It was found that unlike stock tank oil, relaxation times do not depend linearly on viscosity/temperature on a log-log scale. Each of the mixtures forms a different curve.Generalized correlations between viscosity, diffusivity, gas/oil ratio, and NMR relaxation times were developed. First, the relaxation time mixing rule was developed by studying the theory of NMR relaxation mechanism. From the mixing rule, it was found that departure of relaxation times of methane-n-alkane mixtures from linear correlations on a log-log scale can be correlated with the proton fraction of methane, expressed as gas/oil ratio. Thus, correlations between relaxation time, viscosity/temperature, and gas/oil ratio were developed. Correlations between relaxation time, diffusivity, and gas/oil ratio were also developed. There is a linear relation between diffusivity and viscosity/temperature that is independent of composition. From these correlations, viscosity and gas/oil ratio can be estimated from NMR T 1 relaxation time and diffusivity.

Clathrate hydrates are of great importance in many aspects. However, hydrate formation and dissociation mechanisms, essential to all hydrate applications, are still not well understood due to the limitations of experimental techniques capable of providing dynamic and structural information on a molecular level. NMR has been shown to be a powerful tool to noninvasively measure molecular level dynamic information. In this work, we measured nuclear magnetic resonance (NMR) spin lattice relaxation times (T1's) of tetrahydrofuran (THF) in liquid deuterium oxide (D2O) during THF hydrate formation and dissociation. At the same time, we also used magnetic resonance imaging (MRI) to monitor hydrate formation and dissociation patterns. The results showed that solid hydrate significantly influences coexisting fluid structure. Molecular evidence of residual structure was identified. Hydrate formation and dissociation mechanisms were proposed based on the NMR/MRI observations.

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CompoundIa Iv Ferrocene 6.88" 1,l'-Diacetylferrocene 7.05 7.41 4a 7.04 7.67 4b 7.22 7.73 4c 7.16 7.67 aIa and Iv are i0.05 eV. Calibration relative to HXe/@.3.5 (dt, J = 13, 2 Hz, 2 H); 2.9 (brd, J = 13 Hz, 2 H). Interesting, although the mass spectrum of 6d has a strong peak for the molecular ion (mle, 156 for C&"B79Br), the base peak occurs at m/e 76, which corresponds to a loss of HBr to the parent borabenzene ( C S H~B + ) .~ Treating 6d with excess tert-butyllithium followed by ferrous chloride produces bis( 1-tert-buty1borabenzene)iron (4c) in an overall yield of 28%: Mp, 144-145O; 'H N M R (CDC13), 7 8.85 (s, 18 H), 5.65 (d, J = 9 Hz, 4 H), 4.60 (m, 4 H), 4.40 (t, J = 5.5 Hz, 2 H); "B N M R (CDC13) 6 -24.6; mass spectral m/e, 322 (M', C 1 p H z s~~B 2~~F e ) ; uv (CzH50H) 214 (35000), 274 (2170), 312 (1320), 362 (660). 4b has also been produced analogously from 2d with methyllithium and presumably the synthesis could be extended to other 1-substituted analogs by varying the alkyllithium. Compounds 4a and 4b have recently been reported by H e r b e r i~h .~ Thus this synthesis provides a point of convergence for the two methods for producing borabenzenes.Like the previously reported complexes, data indicate that the 1 -substituted-borabenzene is a q6-ligand.1-3 s-Boron coordination to iron is suggested by the air-stability of 4 in contrast to their pyrophoric conjugate acids 6 and by the large upfield shift of 4 relative to 6 in the "B N M R spectra. Similarly the IH N M R chemical shift values show a considerably smaller range than those of q5-cyclohexadienyl iron complexes.'The S7Fe Mossbauer spectrum of 4a has been measured.The isomeric shift relative to NazFe(CN)5NO.2H20 is identical with that of ferrocene, 0.72 mm/sec, while the quadrupole splitting is 1.97 mm/sec, somewhat smaller than that of ferrocene (2.40 mm/sec). A similar reduction in the magnitude of the quadrupole splitting has been observed for ferrocenes with strongly electron withdrawing substituent^.^ This suggests 1 -phenylborabenzene withdraws somewhat more electron density from the iron than do the cyclopentadienyl rings of ferrocene, although the equality of the isomeric shift makes it improbable that there is any large electronic difference at iron. The ionization potentials of 4 have been measured by He(1) ionization, See Table I. The vertical ionization potentials are approximately 0.8 eV greater than ferrocene'O and indeed are similar to those of the electron withdrawing ferrocene 1 ,l'-diacetylferrocene.Friedel-Crafts acetylation of 4b with acetylchloride, aluminum chloride in methylene chloride at 0' gave a 20% yield of a monoacetyl product, 7b: mass spectral mle, 280 (M+, C~~H I~I~B~~~F~O ) ; ir (CDC13) 1662 cm-l; H N M R , 7 9.35 (s, 3 H), 9.13 (s, 3 H), 7.63 (s, 3 H), 5.90 (d, J = 8 Hz, 1 H), 5.50 (d, J = 9 Hz, 1 H), 5.34 (d, J = 9 Hz, 1 H), 4.8-4.3 (m, 5 H), 4.08 (d, J = 6 Hz, 1 H). Since only three a-protons are observed as higher field doublets, the acetyl group must occupy the 2-position. Bis( 1 -tert-butylborabenzene)iron...

Viscosity, diffusivity, relaxation time and gas/oil ratio are important properties in the characterization of reservoirs by NMR well logging and in prediction of production performance. For the past few years, NMR well logging has been used to estimate the formation properties and hydrocarbon liquid/vapor characterization. Previous work has shown that pure alkanes, alkane mixtures, viscosity standards and stock tank crude oils have NMR relaxation times which vary linearly with viscosity/temperature and diffusivity on a log-log scale. However, pure methane at some temperatures and pressures does not follow the same trend. Thus, the linear correlation may not be valid for live crude oils that contain significant amount of methane. Therefore, the study of methane-hydrocarbon mixtures is of interest. An NMR spectrometer equipped with a high-pressure probe was used to study the relationship between NMR T1 relaxation time and viscosity/temperature, diffusivity and gas/oil ratio of methane-hydrocarbon mixtures. Relaxation time and diffusivity measurements of three mixtures were made, methane-n-hexane, methane-n-decane and methane-n-hexadecane. It was found that unlike stock tank oil, relaxation times do not depend linearly on viscosity/temperature on a log-log scale. Each of the mixtures forms a different curve. Generalized correlations between viscosity, diffusivity, gas/oil ratio and NMR relaxation times were developed. First, the relaxation time mixing rule was developed by studying the theory of NMR relaxation mechanism. From the mixing rule, it was found that departure of relaxation times of methane-n-alkane mixtures from linear correlations on a log-log scale can be correlated with the proton fraction of methane, expressed as gas/oil ratio. Thus, correlations between relaxation time, viscosity/temperature and gas/oil ratio were developed. Correlations between relaxation time, diffusivity and gas/oil ratio were also developed. There is a linear relation between diffusivity and viscosity/temperature that is independent of composition. From these correlations, viscosity and gas/oil ratio can be estimated from NMR T1 relaxation time and diffusivity. Introduction There are existing correlations between NMR relaxation time and viscosity for pure alkanes, alkane mixtures and crude oils. In 1961, Brown made relaxation time measurements on a number of crude oils and showed that relaxation time was closely correlated with viscosity.1 Recently, measurements of T2 relaxation times of dead crude oils were made, and it was found that T2 depends linearly on viscosity on a log-log plot for crude oils.2,3,4 There are also works done on deoxygenated pure alkane and alkane mixtures, and it was found that relaxation times of pure alkane and alkane mixtures could also be linearly correlated with viscosity/temperature.5,6,7,8 However, there was no existing correlations between viscosity, diffusivity and NMR relaxation time for live oils. Previous publications of this work have shown that methane-decane mixtures do not follow the same correlation of pure alkanes and alkane mixtures.9,10 The objective of this work was to develop correlations between transport properties (viscosity, diffusivity), Gas/Oil ratio and NMR relaxation time of methane-hydrocarbon mixtures. Equipments Two NMR spectrometers were used to measure relaxation times. One is a low-field spectrometer which operates at 2 MHz with a permanent magnet, the MARAN-2. This spectrometer was used for relaxation time measurements of pure alkanes at 30°C and ambient pressure.

Water-in-oil emulsions are of particular interest concerning methane hydrate formation during crude oil production. The objective of this work is to understand the morphology of the hydrate/water drops in waterin-oil emulsions. Hydrogen nuclear magnetic resonance (NMR) is used to directly measure the formation of methane hydrates in water-in-oil emulsions. A 2 MHz NMR spectrometer is used to investigate the relationship between the drop size distributions of water-in-oil emulsions and methane hydrate formation. The drop size distributions of two crude oil and two model oil emulsions are measured by the pulsed-field gradient with diffusion editing technique. This technique is particularly useful because it does not assume a priori the functional form of the drop size distribution. The amount of liquid water converted to hydrate is directly measured by transverse relaxation measurements. These NMR techniques investigate the entire emulsion sample, and they provide useful information regarding the relationship between drop size distributions and methane hydrate formation in emulsified systems.

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