CC BY
34
CHEMICAL PROBLEMS 2022 no. 2 (20) ISSN 2221-8688
175
UDC 665.61.543.32
DEVELOPMENT AND STUDY OF INHIBITOR TO PREVENT INORGANIC
SALTS DEPOSITION
Kh.I. Hasanov, N.N. Khalilov
«Oil Gas Scientific Research Project» Institute, SOCAR, Baku, Azerbaijan H. Zardabi 88a, AZ1012, Baku E-mail: [email protected]
Received 29.04.2022 Accepted 02.06.2022
Abstract: The paper deals with potential compositions developed for inhibiting scale deposition on oil refining equipment and pipelines based on inhibited hydrochloric acid, dispersant EC 9660A, laprol 4202-2B-30 and water. The density of the produced compositions at 20 °C is 1020-1050 kg/m3, the kinematic viscosity at 20 °C is 30-40 mm2/s, the pour point is minus 5-15 °C, the hydrogen index pH = 2-3. The efficiency of scale inhibition was evaluated by means of common practice which relies on the ability of the chemical to retain calcium and magnesium cations in simulated artificial mineral water. It was established that the compositions at a consumption rate of 50 mg/l generate a better protective effect (76.3-85.6 % ) as compared to cases when the inhibitor consumption was 40 mg/l (73.1-83.2 %) and 30 mg/l (70.4-78.1 %). The compositions with 10 % of mass fraction of laprol 4202-2B-30 have demonstrated higher protective properties.
Keywords: scale inhibitor, inhibited hydrochloric acid, surfactant, inhibition efficiency, calcium sulfate, active agent.
DOI: 10.32737/2221-8688-2022-2-175-182
Introduction
Problems arising from the oil refining services may, in some way, be caused by the formation of complex salt deposits in oil collection, transportation and treatment systems. As for the predominant content in the deposits of certain types of inorganic salts, two groups of salt are specified: carbonate and sulfate. The most common type of deposits of inorganic salts is deposits containing mainly sulfates and carbonates of calcium and magnesium. The composition of deposits in the form of impurities contains oxides of iron and silica, the presence of which is explained by corrosion of oil refining equipment and pipelines. The formation of precipitation results in the damage of valuable equipment, along with time consuming maintenance activities. In an effort to eliminate the build-up of scales the companies are annually faced with costs in the form of lost products [1].
The most effective means of controlling the scale is the use of inhibitors. Inhibitors are
designed to prevent the build-up of mineral deposits of various compositions on the inner surface of oil refining equipment, pipelines, collection and transportation systems of watercut crude, formation pressure maintenance systems and wastewater disposal.
The use of chemicals is the most effective and streamlined way to prevent deposition of inorganic salts. At the moment, the oil industry can largely benefit from the availability of sufficient number of scale inhibitors [2].
Considering the properties and mode of action on supersaturated solutions, scale inhibitors are divided into "threshold" and mixed action chemicals as well as complexing agents [3-5].
It found that inhibitors with a "threshold effect" exhibit the greatest protective effect [1, 3]. This type of inhibitors forms a protective film on the surface of salt "nucleation", helps to retard their growth, and resist when crystals are
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CHEMICAL PROBLEMS 2022 no. 2 (20)
connected to each other and on the surface of the protected equipment.
Complexing inhibitors generate water-soluble anionic or chelate complexes with alkaline earth metal cations. Mixed action reagents demonstrate both "threshold" properties and properties of complexing agents [6, 7].
To ensure effective protection of equipment, the scale inhibitor selected for certain conditions is required to be permanently present in the required amount in the system. The maximum protective effect can be obtained if the inhibitor is injected into the solution
before the beginning of crystallization of inorganic salts [1, 8-11].
Following from cost-effectiveness and considering the nature and conditions of well development, the availability of engineering tools and other factors, various techniques can be applied, however, in oilfield practice, inhibitory methods of protection have received priority to prevent complications associated with scaling and corrosion of equipment.
The purpose of this work is to produce chemicals on the basis of inhibited hydrochloric acid and surface-active substances (SAS), and to analyze them as scale inhibitors.
Practical part
The technical result of this work is to exclude the use of scarce, expensive chemicals such as SNPX 5312C, Incredol, PAF-13, FLOSPERSE HT, FLOSPERSE DISSOLVER, FLOSPERSE PX60N to prevent the deposition of inorganic salts during oil and gas processing on equipment and pipelines of carbonate and terrigenous formations containing hydrochloric acid and SAS [12].
One of the main requirements to scale inhibitors is their adsorption-desorption properties [13, 14]. In this respect the use of chemicals reducing the interfacial tension at the boundary of the oil-inhibiting solution is required to improve the adsorption-desorption characteristics of the scale inhibitor. Due to the adsorption-desorption characteristics, the produced chemicals act as scale inhibitor for a long time and show high efficiency. Treatment of the surface of productive rocks with an inhibitory composition containing hydrochloric acid reduces the surface tension at the "rock-oil-inhibiting solution" interface and makes it possible to better prepare the rock surface for adsorption due to the rejection of film oil and hydrophilization of the surface [15]. At the same time, there is also an increase in the roughness of the rock due to the chemical interaction of hydrochloric acid with carbonate minerals. Besides, hydrochloric acid can clear the surface of the rock from film oil, changing its wettability and, thereby, ensuring uniform and complete adsorption of the scale inhibitor.
Compositions were developed for inhibiting scale deposition on oil refining equipment and pipelines based on inhibited hydrochloric acid, dispersant EC 9660A, laprol 4202-2B-30 and water.
As a constituent of the inhibitor, hydrochloric acid rids the bottom-hole formation zone,
tubing of salt and paraffin-tar deposits. It acts on the rocks of the bottom-hole formation zone creating looseness and etching channels which leads to better permeability and well productivity. Addition of a nonionic SAS (laprol 4202-2B-30) to the solution reduces the value of interfacial tension. As a nonionic SAS, it is adsorbed on asphaltene-resin-paraffin deposits (ARPD) and helps to reduce the surface tension at the interface with the solvent. As a result, the efficiency of dissolution and destruction of ARPD increases. For this reason, the viscosity of oil decreases. The dispersant EC 9660A helps to reduce the surface tension at the interface and thus acts as an auxiliary agent for the action of the nonionic SAS.
The components contained in the composition of the inhibitor, specifically hydrochloric acid, is used in the form of a 21 % aqueous solution. Dispersant EC 9660A is manufactured by Nalco Europe B.V. When preparing the inhibiting compositions, the dispersant EC 9660A was used in the form of a 35 % aqueous solution. Laprol 4202-2B-30 was procured from PJSC "Nizhnekamskneftekhim".
Table 1 indicates the results of the work to produce scale inhibitors. Table 1. Results of preparation of scale inhibitors based on inhibited hydrochloric acid and SAS
№ of sample Amount of substances in the composition, % mass.
Inhibited hydrochloric acid Dispersant EC 9660A Laprol 4202-2B-30 Water
1 25 18 8 49
2 30 18 8 44
3 30 20 8 42
4 30 22 8 40
5 30 18 10 42
6 30 20 10 40
7 30 22 10 38
8 30 18 12 40
9 30 22 12 36
According to the Table, inhibited hydrochloric acid is 25-30 %, dispersant EC-9660A 18-22 %, laprol 4202-2B-30 8-12 %, water 36-49 % in the compositions of the scale inhibitor.
The density of the produced compositions at 20 0C is 1020-1050 kg/m3, the kinematic viscosity at 20 0C is 30-40 mm2/s, the pour point
is minus 5-15 C, the hydrogen index (pH) is 23. The compositions are clear, red-brown liquids.
The efficiency of scaling inhibition was evaluated using a common practice based on the ability of the chemical to retain Ca2+ and Mg2+ cations in artificial mineral water simulating formation water [16]:
CaCl2
MgCl2-6 H2O Na2SÜ4 NaCl
13.6 g/dm3 1.2 g/dm3 13.0 g/dm3 18.8 g/dm3
As required by the testing procedure [15], when the inhibitor is poured into the prepared water, which simulates formation water, it is placed in a thermostat at a temperature of 80oC and kept for 5 hours. At the same time, a control sample is placed without the addition of the chemical. After cooling the samples, the precipitates are filtered. In filtrates, the content of calcium and magnesium ions is determined
by trilonometry [15].
The protective effect of inhibition of inorganic salts was determined by:
^ %=(Ci-Cw/o) / (C0-Cw/o) x 100, where Ci, Cw/o and C0 are respectively the concentration of a salt forming ion in a solution with an inhibitor, mg/l; without inhibitor, mg/l; and in the source water with the initial concentration, mg/l.
Results and discussion
The results of the work made it possible to determine the protective effect of the prepared inhibitors as shown in Table 2. For the
purpose of comparison, the inhibition effect of the known chemicals on scaling in simulated solutions is shown in Table 3.
Table 2. Results of work to determine the protective effect of inhibitors
№ of Inhibitor composition Inhibitor Protective effect
sample consumption, of inhibitor, %
mg/l
19.55 % active agent, 80.45 % water 30 70.4
1 40 73.1
50 76.3
20.6 % active agent, 79.4 % water 30 71.7
2 40 74.3
50 77.5
21.3 % active agent, 78.7 % water 30 74.4
3 40 76.3
50 78.4
22.0 % active agent, 78.0 % water 30 75.4
4 40 77.5
50 80.1
22.6 % active agent, 77.4 % water 30 75.9
5 40 78.2
50 80.8
23.3 % active agent, 76.7 % water 30 78.1
6 40 83.2
50 85.6
24.0 % active agent, 76.0 % water 30 75.1
7 40 77.2
50 79.3
24.6 % active agent, 75.4 % water 30 74.7
8 40 76.3
50 77.1
26.0 % active agent, 74.0 % water 30 71.7
9 40 74.2
50 76.8
As seen from Table 2, the active substance in the compositions is 19.55-26.0 %. The addition of the prepared compositions to the calcium and magnesium sulfate solution at a consumption rate of 50 mg/l leads to a high protective effect (76.3-85.6 %) as compared to cases in which the inhibitor consumption was 40 mg/l (73.1-83.2 %) and 30 mg/l (70.4-78.1 %).
Compositions of samples 3-6 exhibit better protective effect. A distinctive feature of these compositions is that the mass fraction of laprol 4202-2B-30 is 10 %. The presence of a nonionic SAS in the composition of the scale inhibitor below and above 10% leads to worsening of the inhibition quality.
Table 3. The inhibition effect of the known chemicals on scaling in simulated solutions.
№ of a sample Inhibitor brand name Dosage, mg/l Effectiveness, %
1 SNPX 5312C 40 73,9
2 Incredol 40 69,8
3 PAF-13 40 68,1
4 FLOSPERSE HT 40 70,3
5 FLOSPERSE 40 69,8
DISSOLVER
6 FLOSPERSE PX60N 40 71,7
The results of determining the protective given in Fig.1-3. effect of various scale inhibitor formulations are
Fig.1. Correlation between the protective effect of the scale inhibitor (22 % active substance, 78 %
water) and inhibitor consumption
Fig. 2. Correlation between the protective effect of the scale inhibitor (22.6 % active substance,
77.4 % water) and inhibitor consumption
Fig. 3. Correlation between the protective effect of the scale inhibitor (23.3 % active substance,
76.7 % water) and inhibitor consumption
In the summary, proper compositions were developed to prevent the scale deposition on oil refining equipment and pipelines based on inhibited hydrochloric acid, dispersant EC 9660A, laprol 4202-2B-30 and water. The
efficiency of scale inhibition was evaluated by common practice which relies on the ability of the chemical to retain calcium and magnesium cations in simulated artificial mineral water.
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QEYRi-ÜZViDUZ QÖKÜNTÜLdRlMNARADAN QALDIRILMASI ÛÇÛN ÎNHÎBÎTORUN iÇLdNiLMdSi Vd TdDQiQi
X.i. H9S9nov, N.N. Xslilov
"Neftqazelmitddqiqatiayihd " Institutu, SOCAR, Baki, Azdrbaycan e-mail: [email protected]
Xülasa: Neftayirma avadanliqlarinda vd boru kdmdrldrindd duz çôkûntûldrinin aradan qaldirilmasi ûçûn inhibitorlaçmiç xlorid turçusu, ES 9660A markali dispersant, 4202-2B-30 markali laprol vd su dsasinda yeni tdrkibli duzçôkmd inhibitorlari içldnib hazirlanmiçdir. Hazirlanmiç tdrkibldrin 20 °C-dd sixligi 1020-1050 kg/m3, kinematik özlülüyü 30-40 mm2/s, donma tempetaruru mdnfi 5-15 °C, hidorgen göstdricisi pH=2-3 tdçkil edir. Duzçôkmd inhibitorunun effektivliyi reagentin süni hazirlanmiç mineral suyun ümumi hdcmindd kalsium kationlarini tutmaq qabiliyydtind dsaslanan vahid metodika üzrd qiymdtldndirilmiçdir. Müdyydn edilmiçdir ki, içldnmiç tdrkibldr 50 mq/l sdrfiyyatinda müqayisddd daha yüksdk qoruyucu effektd (76.3-85.6 %) malikdirldr ndinki 40 mq/l (73.1-83.2 %) vd 30 mq/l (70.4-78.1 %) sdrfiyyatinda. Tdrkibindd 10 % 4202-2B-30 laprol olan kompozisiyalar daha yüksdk qoruyucu effekt göstdrirldr.
Açar sözhr: duzçôkmd inhibitoru,inhibitirla§mi§ xlorid turçusu,sdthi aktiv maddd, inhibitorlaçma effektivliyi, kalsium sulfat, aktiv maddd.
РАЗРАБОТКА И ИССЛЕДОВАНИЕ ИНГИБИТОРА ОТЛОЖЕНИЯ НЕОРГАНИЧЕСКИХ СОЛЕЙ
Х.И. Гасанов, Н.Н. Халилов
НИПИ «Нефтегаз», SOCAR, Баку, Азербайджан AZ1012, Баку, ул. Зардаби, 88; е-mail: x. qasanov58@gmail. com
Аннотация: Разработаны составы для ингибирования отложений солей, проявляющихся на нефтеперерабатывающих оборудованиях и трубопроводах, на основе ингибированной соляной кислоты, дисперсанта ЕС 9660А, лапрола 4202-2Б-30 и воды. Плотность приготовленных составов при 20 °С составляет 1020-1050 кг/м3, кинематическая вязкость 30-40 мм2/с, температура застывания минус 5-15 °С, показатель водорода pH =2-3. Эффективность ингибирования солеотложения оценивалась по единой методике, основанной на способности реагента удерживать катионы кальция и магния в объеме модельных растворов, имитирующих пластовые воды. Установлено, что наибольший защитный эффект (76.3-85.6 %) приготовленных составов наблюдается при расходе
ингибитора 50 мг/л. Очень высокие результаты по защитному эффекту проявляют составы, в которых массовая доля лапрола 4202-2Б-30 составляет 10 %. Ключевые слова: ингибитор солеотложения, ингибированная соляная кислота, поверхностно-активное вещество, эффективность ингибирования, сульфат кальция, активное вещество.
