New integrated-action oilfield reagent having properties of scaling inhibitor and hydrogen sulfide neutralizer

Article abstract of DOI:10.1134/S1070427215070113

Method for obtaining a new oilfield reagent for inhibition of scaling and neutralization of hydrogen sulfide on the basis of paraformaldehyde, monoethanolamine, and phosphorus(V) oxide was developed.

Full text of DOI:10.1134/S1070427215070113

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2015, Vol. 88, No. 7, pp. 1174−1177. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © E.R. Ishmiyarov, N.T. Rakhimova, D.R. Latypova, M.I. Abdullin, A.I. Voloshin, V.A. Dokichev, 2015, published in Zhurnal Prikladnoi
Khimii, 2015, Vol. 88, No. 7, pp. 1083−1086.
ORGANIC SYNTHESIS AND INDUSTRIAL
ORGANIC CHEMISTRY
New Integrated-Action Oilfield Reagent Having Properties
of Scaling Inhibitor and Hydrogen Sulfide Neutralizer
E. R. Ishmiyarova, N. T. Rakhimovab, D. R. Latypovaa, M. I. Abdullina,
A. I. Voloshinb, and V. A. Dokichevb
a Ufa Institute of Chemistry, Russian Academy of Sciences, pr. Oktyabrya 47, Ufa, Bashkortostan, 450054 Russia
b Ufa State Aviation Technical University, ul. Karla Marksa 12, Ufa, Bashkortostan, 450000 Russia
e-mail: dokichev@anrb.ru
Received July 20, 2015
Abstract—Method for obtaining a new oilfield reagent for inhibition of scaling and neutralization of hydrogen
sulfide on the basis of paraformaldehyde, monoethanolamine, and phosphorus(V) oxide was developed.
DOI: 10.1134/S1070427215070113
The scaling and the increased content of hydrogen
sulfide and mercaptans pose severe problems in develop-
ment and operation of oil-and-gas wells [1–4]. The scaling
process is directly associated with the strong supersatura-
tion of the aqueous medium with difficultly soluble salts
because of the change in the physicochemical parameters
of the oil extraction system (temperature, pressure, gas
evolution, concentration of precipitate forming ions,
etc.). The most effective and technologically convenient
among the presently known methods to tackle with
scaling is the method of scaling prevention with chemi-
cal reagents, scale inhibitors. As scale inhibitors serve
organic derivatives of phosphonic and phosphoric acids,
nonionogenic phosphates, low-molecular polycarboxylic
acids, acid polymers and copolymers, etc. [3]. Upon an
appropriate choice of an inhibitor and its appropriate
application technology, the deposition of organic salts
can be technologically completely precluded along the
whole way of well product motion from a hole bottom
to oil-and-water processing facilities.
and mercaptans in oil should not exceed 100 ppm, with
this figure to be further reduced to 20 ppm. Hydrogen
sulfide neutralizers are used to rapidly and effectively
reduce the content of hydrogen sulfide in extracted oil
by reacting with hydrogen sulfide to give nonvolatile
compounds. An analysis of published data demonstrated
that the most widely used hydrogen sulfide and mercap-
tan neutralizers are those based on formaldehyde and its
derivatives are [5–7].
Despite the considerable number of studies in this
field, published data on oilfield reagents acting as both
scaling inhibitors and hydrogen sulfide neutralizers are
nearly lacking at all. It should be noted that the scaling
becomes more pronounced in the presence of hydrogen
sulfide because of the decreasing solubility of CaCO3 [8].
The goal of our study was to synthesize from parafor-
maldehyde, monoethanolamine, and P2O5 a new reagent
that could simultaneously effectively inhibit the deposi-
tion of CaCO3 and neutralize hydrogen sulfide.
EXPERIMENTAL
In extraction, transportation, and processing of oil,
hydrogen sulfide and mercaptans cause corrosion of the
oil-extraction equipment, contaminate the atmosphere,
and impair the activity of catalysts to the point of their
complete deactivation in oil processing. In 2008, GOST
(State Standard) R 51858–2002 came into effect, accord-
ing to which the maximum content of hydrogen sulfide
NMR spectra were recorded with a Bruker AM-300
spectrometer with working frequencies of 300.13 (1H) and
75.47 MHz (13C). The chemical shifts in the 1H spectrum
are given relative to the TMS internal standard. IR spectra
were recorded with a Shimadzu IR Prestige spectrometer.
1174

NEW INTEGRATED-ACTION OILFIELD REAGENT
1175
Elemental analysis data were obtained on a Euro EA-3000
CHNS analyzer (HEKArech GmbH).
The efficiency of a scaling inhibitor was determined by
capillary blocking in pumping of model produced water
(MPW) through the capillary without an inhibitor (blank
run) and with it. The model produced water containing
Ca2+, Na+, Cl–, and CO32– was pumped at a flow rate of
1 mLmin–1 through a capillary with length of 2.5 mm and
inner diameter of 1 mm at a temperature of 90°C, and the
dynamics of the pressure drop in the capillary, caused by
deposition of CaCO3, was recorded.
1,3,5-Tris(2-hydroxyethyl)hexahydrotriazine (I).
To 6.1 g (0.1 mol) of monoethanolamine was added a
solution of 3.0 g (0.1 mol in terms of formaldehyde) of
paraformaldehyde in 20 mL of methanol and the mixture
was agitated for 2 days. The solvent was evaporated, and
the residue, distilled to give 6.3 g (86%) of a light yellow
viscous fluid. The physicochemical characteristics of
compound (I) were in agreement with published data [9].
The inhibition efficiency was found by the formula
2-[3,5-Bis(2-hydroxyethyl)-1,3,5-hexahydrotri-
azinyl-1]ethyl ester of phosphoric acid (II). To 50.0 g
(0.228 mol) of hexahydrotriazine (I) was added under
vigorous agitation at 0°C 16.14 g (0.114 mol) of P2O5
until a homogeneous mass was formed. The resulting
mixture was heated to 80°C for 1 h. A 66.0-g (96%) por-
tion of a light yellow viscous fluid was obtained. Found,
%: C 36.18, H 7.38, N 14.21. C9H22N3O6Р. Calculated,
%: C 36.12, H 7.41, N 14.04, Р, 10.35.
E = (Δp1 – Δp2)/Δp1,
where Δp1 is the pressure drop in the capillary in pump-
ing-through of MPW without a scaling inhibitor (kPa),
and Δp2, that with a scaling inhibitor (kPa).
The efficiency of a reagent as hydrogen sulfide neu-
tralizer in oil and oilfield water was determined by the
standard procedure.
IR spectrum, ν, cm–1: 978, 1076, 1249, 1355, 1457,
1653, 1675, 2872–2960, 3100–3570 (ОН). H NMR
RESULTS AND DISCUSSION
1
spectrum (300 MHz, δ, ppm, CD3OD): 2.82 t (4H,
NCH2C), 2.98 m (4H, NCH2N), 3.31 m (2H, NCH2C),
3.82 t (2H, CH2O), 3.88 (2H, CH2OР), 4.14 m (2H,
NCH2N), 4.70 m (4Н, ОН).
The 1,3,5-hexahydrotriazine fragment interacts with
hydrogen sulfide and thereby neutralizes this compound
and phosphoric acid derivatives inhibit the crystallization
rate. Therefore, it was of interest to develop a method
for obtaining phosphorylated 1,3,5-tris(2-hydroxyethyl)-
hexahydrotriazine and study its properties as CaCO3
deposition inhibitor and hydrogen sulfide neutralizer.
Single-reactor method for synthesis of 2-[3,5-bis(2-
hydroxyethyl)-1,3,5-hexahydrotriazinyl-1]ethyl ester
of phosphoric acid (II). To a solution of 3.0 g of para-
formaldehyde in 20 mL of methanol was added 6.1 g
(0.1 mol) of monoethanolamine and the mixture was
boiled with reflux for 3.5 h. The solvent was evaporated
and 2.37 g (0.017 mol) of P2O5 was added under vigor-
ous agitation. The resulting mixture was heated to 80°C
for 1 h, with 9.5 g (95%) of light yellow viscous liquid
obtained.
1,3,5-Tris(2-hydroxyethyl)hexahydrotriazine (I) was
produced via triple cyclic condensation of monoetha-
nolamine with methoxymethanol in methanol in nearly
quantitative yield. Under the chosen conditions and at
a fivefold molar excess of methanol in terms of form-
aldehyde, paraformaldehyde is nearly fully converted
to methoxymethanol, which favors a selective course
Scheme 1.
P2O5
CH3OCH2OH
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 88 No. 7 2015

1176
Δp, kPa
ISHMIYAROV et al.
E, %
τ, s
τ, s
Fig. 1. Effect of phosphorylated 1,3,5-tris(2-hydroxyethyl)
hexahydrotriazine (II) on the process of CaCO3 deposition
at concentrations of (1) 0, (2) 10, and (3) 20 mg L–1 at 90°C.
(Δp) Pressure drop and (τ) time.
Fig. 2. Efficiency E of hydrogen sulfide neutralization with
phosphorylated 1,3,5-tris(2-hydroxyethyl)hexahydrotriazine
(II) vs. the interaction duration τ at reagent : hydrogen sulfide
molar ratios of (1) 9 : 1 and (2) 6 : 1.
of the reaction [10]. Heating of hexahydrotriazine (I)
with phosphorus(V) oxide at a 2 : 1 molar ratio and
temperature of 80°C gives 2-[3,5-bis(2-hydroxyethyl)-
1,3,5-hexahydrotriazinyl-1]ethyl ester of phosphoric acid
II in 96% yield. The 1H NMR spectrum of compound II
contains, together with the signals of methylene protons
of the triazine ring at 2.82 and 4.14 ppm, also a triplet at
3.88 ppm and a broadened singlet at around 4.70 ppm,
associated with protons of the POCH2– and HO groups.
The IR spectrum shows absorption bands at ~978 and
~1249 cm–1, characteristic of stretching vibrations of
P–O–C phosphoric acid esters [11] (Scheme 1).
with monoethanolamine for 3.5 h and P2O5 was added
to the resulting reaction mass to give phosphorylated
1,3,5-tris(2-hydroxyethyl)hexahydrotriazine (II) the pu-
rity of which is about 95% according to 1H NMR data.
A study of phosphorylated 1,3,5-tris(2-hydroxy-
ethyl)hexahydrotriazine (II) demonstrated that this
compound has properties of both a scaling inhibitor
and a hydrogen sulfide neutralizer. At concentrations of
10 and 20 mg L–1, the reagent nearly fully inhibits the
process of CaCO3 deposition, with its efficiency being
about 98% (Fig. 1).
The reagent was tested by the standard procedure for
determining the efficiency of hydrogen sulfide absorp-
tion. It can be seen in the table that even at a so small
consumption coefficient of reagent II, the efficiency of
hydrogen sulfide absorption by the neutralizer exceeds
95%. Figure 2 shows the dependence of the neutraliza-
Of particular interest are methods for synthesis of
the compounds without production and isolation of
intermediate substances. In this context, we developed
a single-reactor double-stage method for obtaining
phosphoric acid ester II: methoxymethanol was boiled
Efficiency of hydrogen sulfide neutralization by reagent II
H2S concentration, mg L–1
H2S-Containing
liquid
Consumption coefficient
K, mg mg–1 2S
Efficiency, %
before absorption
after absorption
Sorochinsk oil
Sorochinsk oil
Sorochinsk water
3
3
3
1932
1700
260
579.6
221
70
87
99
Trace amounts
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NEW INTEGRATED-ACTION OILFIELD REAGENT
1177
tion efficiency on the exposure duration, whence follows
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Reagent II is compatible with mineralized stratal
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The study was supported by the Russian Science
Foundation (project no. 14-33-00022).
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