ISSN 0012-5008, Doklady Chemistry, 2008, Vol. 423, Part 1, pp. 283–285. © Pleiades Publishing, Ltd., 2008.Original Russian Text © L.M. Petrova, N.A. Abbakumova, G.V. Romanov, 2008, published in Doklady Akademii Nauk, 2008, Vol. 423, No. 2, pp. 195–197.

283

The notion of petroleum disperse systems (PDSs) iswidely used in petroleum production, transport, andrefining. The composition and structure of a PDS areknown to affect the dynamic properties of oils [1–4]. Itis common practice to study PDS mobility, which is thereciprocal value of viscosity, as a function of compo-nent concentrations in petroleum. There are no quanti-tative correlations between the dynamic properties andstructure of components of a PDS. To fill in this gap, westudied the structure of these components and ascer-tained the effect of their structure on the interactionsbetween neighboring structural units of a PDS in Devo-nian oils (table, samples 1–6;

µ

= 14.2–44.0 cSt) andhigher viscosity Carboniferous oils (table, samples 7–12;

µ

= 49.3–91.9 cSt).

Petroleum disperse systems contain complex struc-tural units (CSUs) and a dispersion medium. In asphalt-ene–resinous oils, a CSU has an asphaltene (A) core.The inner part of the solvation shell is represented byalcohol–benzene resins (ABRs); the peripheral part isrepresented by benzene resins (BRs). The dispersionmedium consists of hydrocarbons with onset boilingtemperatures of up to

200°ë

and oleic hydrocarbons(O). The effect of the PDS composition derived fromthe component distributions in test petroleum sampleson the decrease in PDS mobility is expressed as anincreased concentration of CSUs (Fig. 1) on account ofthe high contribution of their constituent solvation shell(Fig. 2).

A common structural feature of the components isthe occurrence of paraffin and aromatic structures.Therefore, from the optical densities

D

of the absorp-tion bands at 720, 1380, and 1600 cm

–1

associated withmethylene and methyl groups and aromatic C=C bonds

in the IR spectra, we calculated the structural parameter(aliphaticity Al) for each component [5]:

Al =

The aliphaticity decreases in the followingorder: oils—benzene resins—alcohol–benzene res-ins—asphaltenes. As a measure of the componentinteractions in the PDS, we propose to use the alipha-ticity parameter for calculating the pair structural affin-ity of PDS components (table):

K

O, BR

= Al

BR

/Al

O

, %, is the structural affinity of thedispersion medium and the peripheral part of the solva-tion shell;

K

BR, ABR

= Al

ABR

/Al

BR

, %, is the structural affinity ofthe peripheral and inner parts of the solvation shell; and

K

ABR, A

= Al

A

/Al

ABR

, %, is the structural affinity ofthe inner part of the solvation shell and the core.

Pulsed NMR spectroscopy was used to studydynamic phenomena on the molecular scale; the spin–spin relaxation amplitude

N

is in direct proportionalityto the petroleum mobility. This amplitude is differenti-ated over two or three phases

‡

,

b

, and

c

, which arecharacterized by spin–spin relaxation times

T

2

i

and theproton concentration (population)

P

i

. These phases

D720 D1380+D1600

-----------------------------.

Structure and Mobility of Components of Petroleum Disperse Systems

L. M. Petrova, N. A. Abbakumova, and G. V. Romanov

Presented by Academician O.G. Sinyashin June 3, 2008

Received June 20, 2008

DOI:

10.1134/S0012500808110050

Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center, Russian Academy of Sciences, ul. Akademika Arbuzova 8, Kazan, 420088 Tatarstan, Russia

CHEMISTRY

20

10

2 3 4 5 6 7 8 9 10 11 12

Petroleum sample no.

40

60

80

100

Concentration, %

1 2

Fig. 1.

Distribution of (

1

) dispersion medium and (

2

) com-plex structural units in the PDS.

284

DOKLADY CHEMISTRY

Vol. 423

Part 1

2008

PETROVA et al.

refer to petroleum components with high, medium, andlow molecular mobilities, which can be assigned to thedispersion medium, solvation shell, and core, respec-tively [6]. The mobility of the dispersion medium wasestimated as (table)

and the mobility of complex structural units as

.

The structural affinity of molecules in the inner partof the solvation shell and core

K

ABR, A

is close in Devo-

Na

T2aPa

100--------------=

Nb Nc+T2bPb T2cPc+

100----------------------------------=

nian and Carboniferous oils and is about 70%. Thestructural affinity of the components of the peripheraland inner parts of the solvation shells

K

BR, ABR

is about50%, being slightly lower in Carboniferous oils. Theamplitude of the signal of CSUs also tends to decrease.A more considerable feature of Carboniferous oils asdistinct from Devonian oils is the increased structuralaffinity of the components of the dispersion mediumand the peripheral part of the solvation shells of CSUs,

K

O, BR

(45.9–60.3% against 27.7–41.5%). This isequally true for the dispersion medium (a mixture ofhydrocarbons with a 200

°

C onset boiling point andoleic hydrocarbons). The dispersion medium is charac-terized by lower signal amplitudes. In the disperse sys-tem of Carboniferous oils, probably, the low structuralaffinity of the solvation shell components decreases thecompactness of CSUs, while the high affinity of thecomponents of CSUs and the dispersion mediumincreases the degree of their interaction. Thus, theweakening of intermolecular component interactionsinside CSUs, in particular, in the solvation shell, andthe strengthening of intermolecular interactionsbetween CSUs and hydrocarbons of the dispersionmedium decrease the mobility of the PDS.

Varying the contribution of intermolecular inter-actions between components of PDSs, one can con-trol the properties of crude oils and refining prod-ucts. Our data can also be used for predicting thebehavior of disperse oil systems in petroleum pro-duction and transportation.

10

10

2 3 4 5 6 7 8 9 10 11 12

Petroleum sample no.

15

25

35

Concentration, %

1 2

30

20

5

Fig. 2.

Distribution of (

1

) solvation shell and (

2

) core inCSUs.

Mobility and structural affinity of components of the PDS

Sample no. Viscosity

µ

, cSt

Dispersion medium, % Complex structural unit, %

N

a

K

O, BR

N

b

+

N

c

K

BR, ABR

K

ABR, A

Devonian oils

1 17.0 60.7 28.6 13.2 56.3 76.7

2 14.2 51.6 27.7 10.2 60.6 65.5

3 44.0 75.5 39.3 11.2 57.6 75.8

4 35.8 61.3 38.9 14.9 54.3 72.6

5 43.2 33.8 33.7 10.5 53.1 72.4

6 28.8 59.9 41.5 13.9 55.9 75.8

Carboniferous oils

7 45.7 33.6 60.3 8.7 42.6 71.0

8 49.3 23.5 49.4 5.5 51.2 72.9

9 55.6 27.0 47.0 5.6 48.9 69.6

10 56.7 27.7 57.3 8.7 41.9 81.1

11 52.7 33.3 47.8 11.5 47.7 68.1

12 91.9 17.1 45.9 5.0 58.8 70.5

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STRUCTURE AND MOBILITY OF COMPONENTS OF PETROLEUM DISPERSE SYSTEMS 285

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