Use of Pulsed Nmr Spectroscopy to Measure the Amount of Solid Deposits As a Function of Temperature in Waxy Crudes

Ruffier-Meray, V.; Roussel, J.C.; Défontaines, Anne-Dominique

doi:10.2516/ogst:1998048

Cited by 7 publications

(10 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, during our CPMG measurements performed at 20 MHz, we cannot detect the magnetization associated with n-paraffin crystals, which have a relaxation time T 2 of 70 μs. 21 M (t = 0) varies according to the inverse of temperature. To correct the effects related to temperature variation, the measured magnetization is corrected by Curie's law.…”

Section: Methodsmentioning

confidence: 99%

“…Nuclear magnetic resonance (NMR) relaxometry has been used to characterize waxy crude oils and in particular to determine the n-paraffin content in crude oils and their distributions. 21,22 Furthermore, NMR relaxometry has also been used to understand the role of inhibitors on wax crystallization. model oils, but few studies have been carried out directly on crude oils.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Probing Multiscale Structure and Dynamics of Waxy Crude Oil by Low-Field NMR, X-ray Scattering, and Optical Microscopy

et al. 2020

View full text Add to dashboard Cite

Wax deposition is one of the major concerns for waxy crude oil production and transportation. A better understanding and prediction of fluid properties related to this issue require knowledge of the medium structuration at scales ranging from nanometers (molecules) to a few micrometers (crystals). For this purpose, the behavior of a waxy crude oil in the bulk was compared to that of a model oil over a wide range of temperatures above and below the wax appearance temperature. The combined use of cross-polarized microscopy (CPM) and the implementation of innovative techniques for the field such as small-and wideangle X-ray scattering and low-field nuclear magnetic resonance has provided a more precise idea of the structure of these two types of fluids. If the nature of the orthorhombic crystals and their lamellar shape are identical for both fluids, a very appreciable difference is highlighted in their chain axis dimensions. The n-paraffin crystal size is larger than 120 nm in the model oil. In crude oil, it is only about 1−10 nm with a long-range order in the directions perpendicular to the chain axis and a monomolecular thickness in the chain axis. Moreover, from the model oil CPM images, we observed aggregates of lamellar shape crystals. Because the model oil does not contain asphaltenes and resins, the crystals are larger and the branches divide significantly less than in crude oil, which results in a trapped liquid proton population unobservable in the model oil. All these observations give a vision of the structure of n-paraffin crystals. It is made of aggregates of relatively dense lamellae in the center and more aerated lamellae at the periphery, which split into several branches.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probing Multiscale Structure and Dynamics of Waxy Crude Oil by Low-Field NMR, X-ray Scattering, and Optical Microscopy

et al. 2020

View full text Add to dashboard Cite

show abstract

“…A better understanding of the overall phase behavior, including the popular gas-liquid equilibria and wax crystallization characteristic, would help to analyze the reservoir performance and design the processing facilities. Recently there is a growing body of worldwide interests 4,5,[9][10][11][12][13][14][15][16][17][18][19][20][21][22] in the phase behavior of gas condensate with high wax content, or precisely the heavy normal alkanes with high melting temperature. One may encounter wax precipitation at temperatures as high as 65.55°C 13,14 .…”

Section: Introductionmentioning

confidence: 99%

Phase Behavior of Highly Waxy Gas Condensate Systems

et al. 2001

View full text Add to dashboard Cite

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractAs still deeper formations are drilled, gas condensates containing high carbon-number hydrocarbons which may precipitate during production and in the reservoir, are encountered. An increasing focus of attention on its phase behavior has been made worldwide in recent years. The main purpose of this paper is to investigate experimentally the characteristics of phase behavior of this new type of gas condensate systems with high wax content. Therefore, a series of experiments are carefully made for different GOR fluids, including constant composition expansions and the determination of wax deposition points. The separator gas and liquid are collected from the same producer and recombined in the laboratory to cover the ranges of GOR encountered in the field.The results show that the quality lines of the highest GOR fluid in two-phase region are parallel to each other and terminated at the appearance of wax deposition. Thus the fluid has no convergence point, or critical point. It is also found that the biphase regions expand with the increase in GOR. In other words, gas injection may highly increases the saturation pressure locus contrary to the usual belief that the two-phase region will become smaller as more gas injected into the reservoir leads to more leanness of the reservoir fluid. Another interesting finding is that the more amounts the heavy hydrocarbons, the lower dew-& bubble-point pressures of the gas condensate systems used in this study. This is also contrary to the previous literature results that increasing amounts of heavy hydrocarbons increase the retrograde dew point pressure. Thus the deduced conclusion 28 that a compositional gradient in the segregated fluids results in higher observed dew point pressures at the bottom of the fluid column, may not be made to the highly waxy gas condensate systems used in this study.Additionally we also found the wax deposition temperature increased with decreasing GOR.

show abstract

“…The first transfer of the SFC method to petroleum crudes was by Pedersen et al [4]. Recently, Ruffier-Meray et al [5] applied a pulsed NMR technique to measure the amount of solid (the solid content, SC) in waxy crude oils, when compositions of the solid and liquid phases could be estimated. TD-NMR has also been used to investigate the organization of the solid phase and molecular movements in alkanes and paraffin samples [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Correction of biased time domain NMR estimates of the solid content of partially crystallized systems

Kané¹,

Djabourov²,

Volle³

et al. 2002

Appl. Magn. Reson.

View full text Add to dashboard Cite

The solid content values obtained from the intensity of the nuclear magnetic resonance free induction decay signal of partially crystallized samples such as fats, supersaturated solutions, solid dispersions of waxes, gels are biased due to the difference between the proton density and mass density of the samples. It is shown here that this can be easily corrected with the specific volumes (determined gravimetrically) and proton densities (determined by time-domain nuclear magnetic resonance) of completely liquefied models of the solid and liquid phases and provided that the total amount of crystallizable material is known. The corrected data are in excellent agreement with the values obtained by differential scanning calorimetry for both model systems and real petroleum samples.

show abstract

Use of Pulsed Nmr Spectroscopy to Measure the Amount of Solid Deposits As a Function of Temperature in Waxy Crudes

Cited by 7 publications

References 0 publications

Probing Multiscale Structure and Dynamics of Waxy Crude Oil by Low-Field NMR, X-ray Scattering, and Optical Microscopy

Probing Multiscale Structure and Dynamics of Waxy Crude Oil by Low-Field NMR, X-ray Scattering, and Optical Microscopy

Phase Behavior of Highly Waxy Gas Condensate Systems

Correction of biased time domain NMR estimates of the solid content of partially crystallized systems

Contact Info

Product

Resources

About