Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 5, pp. 751−754.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © E.V. Mal’tseva, A.V. Bogoslovskii, N.V. Yudina, 2012, published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 5, pp. 750−754.
OF SYSTEMS AND PROCESSES
Application of the Low-Frequency Vibratory Method
for Determining the Parafﬁ n Crystallization
Onset in Dispersed Petroleum Systems
E. V. Mal’tseva, A. V. Bogoslovskii, and N. V. Yudina
Institute of Petroleum Chemistry, Siberian Branch, Russian Academy of Sciences, Tomsk, Russia
Received November 14, 2011
Abstract—Crystallization onset of parafﬁ ns was studied by the low-frequency vibratory method in various kinds
of dispersed petroleum systems before and after introduction of additives.
One of problems in extraction and transportation
of oil is that asphalt-tar-parafﬁ n deposits (ATPDs)
are formed on pipeline walls. As a result of a local
decrease in the temperature of oil in the near-wall layer,
its parafﬁ n-dissolving capacity becomes lower and
parafﬁ ns adhere to pipeline walls [1, 2]. The deposition
of parafﬁ ns is considered to be reversible. However,
parafﬁ ns contain a rather large amount of tars and
asphaltenes forming heterogeneous microscopically
dispersed systems. Microscopic particles of systems
of this kind have widely diverse structural states and
exhibit a thermodynamic stability against being split to
molecular dimensions [3, 4].
Development of methods for diminishing the amount
of ATPDs  requires information about the crystalliza-
tion onset point of parafﬁ ns in an appropriate medium
and about the strength and energy of interaction of par-
ticles being formed. The approaches that can determine
the strength and energy of the interparticle interaction
of dispersed petroleum systems (DPSs) are based on
a study of their structural-rheological characteristics .
One of methods for determining rheological param-
eters characterizing the behavior of parafﬁ ns in DPSs
is the low-frequency vibratory technique. It is based on
measuring the retarding force acting on a probe oscil-
lating in a ﬂ uid. The method uses sonic and lower os-
cillation frequencies and can be named low-frequency,
although this term is conditional and mostly reﬂ ects
speciﬁ c technological features of the required appara-
tus [6–9]. The basic concept is the “mechanical resis-
tance” related to the viscosity of the medium in which
the probe is placed. In the theory of electric circuits, this
term corresponds to the “electrical resistance” and the
reaction of a continuous medium to an alternating-sign
mechanical load and ac transport are described by iden-
tical differential equations.
The goal of our study was to examine by low-
frequency vibratory viscometry the crystallization of
parafﬁ ns in DPSs in relation to temperature and content
of depressor additives.
As objects of study were chosen oils differing in the
content of parafﬁ ns: P1, parafﬁ n; and P2 and P3, high-
parafﬁ n. The content of asphaltenes was determined
by the “cold” Holde method. Tarry substances and
parafﬁ ns were quantitatively determined by the column-
adsorption method on a silica gel (thermal activation
at T = 250°C for 6 h). The setting temperature of oil,
Ts, was measured with an INPN Kristall instrument
The mechanical resistance Z was determined with
a Reokinetika vibratory viscometer (Tomsk) as a force