Composition and Crystal Form of the Petroleum Waxes

Ferris, S. W.; Cowles, H. C.; Henderson, L. M.

doi:10.1021/ie50258a021

Cited by 11 publications

(6 citation statements)

References 1 publication

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“…Approximately 1.0 mg. of hydrocarbon was crystallized on each slide. Figure 1, Examples of the Three Types of Wax Crystals (4) í.…”

Section: Methodsmentioning

confidence: 99%

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Crystal Types of Pure Hydrocarbons in the Paraffin Wax Range

Clarke¹

1951

Ind. Eng. Chem.

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The Atlantir Refining Co., Philadelphia, Pa.This study of the crystal types of pure hrdrocarbons was undertaken to secure data for application to wax processing, and to determine why a paraffin wax niay form three different types of crystals-needles, plates, and malcrystalline masses.Twenty-three pure hydrocarbons comprising paraffinic, naphthenic, and aromatic compounds in the molecular weight range of paraffin wax were obtained from il.P.1. Project 42. These pure hydrocarbons were crystallized from the melt a t different rates and from solutions of ethyl acetate and nitrobenzene a t different rates and over a wide range of temperatures. Crystals of each pure hydrocarbon except n-hexacosane were prepared in each of three predominating types: plates, needles, and nialcrystalline masses. Needle crystals could be obtained from n-hexacosane only by the additinn of small amounts of HE crystallization of paraffin waxes as needles, plates, and T malcrystalline masses has been the subject of many studies.Various theories have been advanced to explain why a paraffin wax may form these three different types of crystals. This paper presents data which reconcile differences in the theories.This study of the crystal types of pure hydrocarbons was undertaken in order to secure accurate fundamental data for application to wax processing.Twenty-three pure hydrocarbons comprising paraffinic, naphthenic, and aromatic compounds in the paraffin wax molecular weight range were obtained from A.P.I. Project 42. These pure hydrocarbons were crystallized from the melt and from solution under widely different conditions.The study of these pure hydrocarbon crystals included: the size and external shape of the crystals, the factors which influence the type of crystal formed, the optical properties and crystal systems of the crystals, and the similarity of the pure hydrocarbon crystals to paraffin wax crystals.The shape and size of wax crystals have long been studied. The microscopist refers to the external shape of a crystal as its crystal habit. The two crystal habits which are most frequently observed for paraffin waxes are plates and needles. Plates are found in pressable wax distillates and in refined waxes (8).Needles are found in sweatable slack waxes.A wax distillate is the fraction of a crude petroleum which contains the paraffin wax. To separate the paraffin wax from the oil, the wax distillate may be chilled until the wax crystallizes and the resultant slurry may be filter pressed. If the wax forms a filter cake from which the oil drains easily the wax distillate is pressable. If the oil cannot be separated well from the wax crystals in the pressing operation, the wax distillate is unpressable.The slack wax is melted and charged into the sweat ovens where the wax is chilled to solidify it somewhat and then it is slowly heated. If oil and low melting waxes drain away from the slack wax during the sweating operation and leave a high yield of wax with low oil content, the slack wax is sweatable. If a wax of low oil contentThe wax le...

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“…Approximately 1.0 mg. of hydrocarbon was crystallized on each slide. Figure 1, Examples of the Three Types of Wax Crystals (4) í.…”

Section: Methodsmentioning

confidence: 99%

“…Typical examples of the three types of wax crystals are shown in Figure 1. These photomicrographs of wax crystals are from the work of Ferris and coworkers (4).…”

mentioning

confidence: 99%

Crystal Types of Pure Hydrocarbons in the Paraffin Wax Range

Clarke¹

1951

Ind. Eng. Chem.

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“…The melting point of wax is approximately about 52 °C, so it is solid at ambient temperature. Density of wax is around 900 kg/m 3 (Ferris et al 1931).…”

Section: Test Samplesmentioning

confidence: 99%

Formation damage induced by wax deposition: laboratory investigations and modeling

Sandyga

Struchkov

Рогачев

2020

J Petrol Explor Prod Technol

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There are oil fields, wherein favorable conditions for the formation damage induced by wax deposition are created during production. The damage can be expressed by a decrease in porosity and permeability and a reduction in the drainage area. There are only a few unconventional fields, and this makes them unique. To prevent this complication, it is necessary to control the field production. Assuming the presence of such problem, the conventional reserves may turn into difficult oil reserves whose production is problematic, which will compromise the project profitability. The key to the problem is associated with the experimental procedure and research conditions for investigation wax crystallization in oil, being the subject of this paper. The authors showed that the use of WAT measurement technique in an open measuring system is not enough to control wax deposition in the reservoir pore volume. Based on the results of the flooding technique and micro-computed tomography, a digital core, that allows to simulate fluid flow in the porous medium of the core before and after formation damage, has been created. The calculation of the change in the thermal field around the injection well over time, according to the extended Lauwerier's concept, has been carried out. WAT of a wax-bearing solution was measured by the rheology method using an open measuring system (plate-to-plate measuring system under atmospheric pressure), and the dependence of viscosity versus temperature was obtained during experimental studies. The temperature was decreased from 60 to 10 °C at a cooling rate of 1 °C/min. The experiment was carried out at atmospheric pressure and a shear rate of 5 s −1 . Also, filtration technique and micro-computed tomography were used. The dependence of the pressure gradient versus temperature and the pore throat diameter distribution functions for the initial core and core with organic scales were obtained. The flooding experiment was carried out at a constant flow rate of 0.5 cm 3 /min and confining pressure of 4.1 MPa. The temperature was decreased from 40 to 33 °C at a cooling rate of 1 °C/h. The inflection points on the curves viscosity versus temperature and pressure gradient versus temperature confirm the WAT. The results of the laboratory experiments showed that WAT, measured by the rheology method is 3-4 °C lower than WAT, measured by the flooding technique. The results of the micro-computed tomography showed that initial porosity decreased from 9.0 to 2.1% as a result of wax deposition. The pore throats with diameters from 20 to 70 μm are involved in the clogging with wax. The calculation results confirmed the possibility of cooling the near-wellbore area of injector to a temperature equal to WAT and the cold front movement to the producing wells. The production profiles calculated based on the models of porosity and permeability reduction, showed that wax deposition in the near-wellbore area can cause a significant decrease in the productivity index. An effective remediation technology for injection wells ...

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“…The melting point of wax is approximately about 52 °C, so it is solid at ambient temperature. Density of wax is around 900 kg/ m3 (Ferris et al 1931).…”

Section: Measurement Proceduresmentioning

confidence: 99%

Investigations of temperature and dilution effect on rheological properties of waxy crude oil

Struchkov

Roschin²,

Litvin³

et al. 2019

J Petrol Explor Prod Technol

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The purpose of the paper is to study the effect of temperature and hydrocarbon solvent addition on thixotropy of waxy crude oil. Oil is a complex multicomponent hydrocarbon system. There are many interactions between wax and asphaltene, wax and aromatics, asphaltene and resins in original oil. For example, the dispersion of asphaltenes is known to be influenced by resins. The resins are adsorbed onto the surface of the asphaltenes, whereby the asphaltenes are not aggregated. Wax is adsorbed by fine asphaltene particles and wax appearance temperature (WAT) observed at low temperature (formed wax crystals too small to be detected by measuring system). The authors of the paper have studied the separate effect of two solvents (kerosene and diesel fuel), wax concentration and impurities (kaolinite) on WAT to understand how all these factors affect WAT in wax-bearing solutions individually. Wax-bearing solutions in wax concentration range from 10 to 60% by weight were investigated by the visual and rheological methods under atmospheric pressure. It is shown that the diesel-based solutions have higher WAT than the kerosene-based solutions. Studies have shown that the increase in wax concentration in solution leads to an increase in WAT. The paper describes that the addition of impurities (kaolinite) to the solutions resulted in an increase in WAT. Besides, it is shown that WAT obtained by rheological method is higher on average of 1 °C than WAT obtained by visual method. The authors suggested that under constant other conditions (pressure, resin and asphaltenes content, etc.) an increase in wax content in oil and the content of impurities will lead to an increase in WAT. The scientific basis for this conclusion is that, in the future we can, adding or removing from solution hydrocarbon components, with certain assumptions, simulate the properties of oil. In particular, this will allow us to study separate interactions between the wax and asphaltene, wax and aromatics, and wax and naphtha compounds, and abstract away from other factors. The waxy crude oil production in the Samara region is complicated by impurities entrainment and non-Newtonian properties of oil. The investigations of waxy crude oil were provided with light scattering method (in near infrared region), microscopy under high pressure with the grain size analysis (visual) and a rheological method. We obtained the unique «viscosity superanomaly» discovered by Vinogradov and Malkin (Rheol Acta 5(3):188-193, 1966) at low temperatures and shear stress by rheological method under atmospheric pressure. The area of the hysteresis loop on the flow curve increases as the temperature decreases, which is caused by the formation of the lattice by wax. We have also shown that the use of solvent and the increase in temperature allow to reduce «viscosity superanomaly». Simultaneous use of light scattering and microscopy under high-pressure methods allows increasing in accuracy of measuring. For waxy crude oil, there will also be a difference between rheological and visual...

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Composition and Crystal Form of the Petroleum Waxes

Cited by 11 publications

References 1 publication

Crystal Types of Pure Hydrocarbons in the Paraffin Wax Range

Crystal Types of Pure Hydrocarbons in the Paraffin Wax Range

Formation damage induced by wax deposition: laboratory investigations and modeling

Investigations of temperature and dilution effect on rheological properties of waxy crude oil

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