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Energy & Fuels 2008, 22, 1502–1508
Laboratory Experiments and Field Tests of an Amphiphilic Metallic Chelate for Catalytic Aquathermolysis of Heavy Oil Yanling Chen,*,† Yuanqing Wang,‡ Chuan Wu,† and Fei Xia† Faculty of Materials Science and Chemical Engineering and The Faculty of Resources, China UniVersity of Geosciences, Wuhan 430074, P. R. China ReceiVed January 6, 2008. ReVised Manuscript ReceiVed February 27, 2008
An amphiphilic metallic chelate-aromatic sulfonic iron was synthesized for the first time, characterized by Fourier transform infrared (FT-IR) spectroscopy, and then used in catalytic aquathermolysis of heavy oil both in the laboratory and field. The laboratory results showed that this new catalyst was efficient, universal, and superior to other efficient catalysts we have synthesized before; in addition, for EX35 heavy oil, it led to a evident viscosity reduction by 90.66% at 200 °C with 14.66% in conversion of heavy contents to light contents. To evaluate the its performance, the structure and group composition of heavy oil was analyzed by FT-IR, thin-layer chromatography-flame ionization detection (TLC-FID), gas chromatography/mass spectrometry (GC/ MS), 1H NMR, and elemental analysis (EL) before and after the aquathermolysis. It is found that the changes of the composition and structure of the heavy oil can lead to the viscosity reduction. In field tests of G61012 and G6606 wells in the Henan oilfield, the production increased by 188.7 and 217 t in 14 d (an observed period) after catalytic aquathermolysis technology, respectively, and the viscosity of oil reduced at a rate of 79.66% and 82.25%.
1. Introduction With the increasing demands of energy resources and the serious shortage of conventional hydrocarbon resources, heavy oil, a kind of unconventional hydrocarbon resource with great potential, has attracted worldwide interest. However, its high viscosity and solidification often cause difficulties in exploiting it. Many techniques such as thermal recovery, chemical recovery, microbial recovery, etc. have thus been developed and adopted for heavy oil exploitation.1,2 Steam stimulation, a type of thermal recovery, is the most widely used and most effective way to recover ordinary heavy oils in the world. Much research results show that injection steam cannot only reduce the viscosity of heavy oil but also react with some components of the heavy oil and of the reservoir minerals, thereby leading to changes in the heavy oils’ properties and compositions. Hyne et al.3 in 1982 described all of the reactions between steam heavy oil and minerals as “aquathermolysis”. They4–6 found that, after aquathermolysis, the amounts of saturates and aromatics increased, while the amounts of resin and asphaltene decreased. However, in * Author to whom correspondence should be addressed. Tel.: 8613886113362. Fax: 86-027-87801763. E-mail:
[email protected]. † Faculty of Materials Science and Chemical Engineering. ‡ The Faculty of Resources. (1) Hu, C. Z. HeaVy Oil Exploitation Technology; Petroleum Industry Publishing Inc: Beijing,1998. (2) Lu, L. H.; Li, M. H.; Su, Y. L. The Overview of the Heavy Oil Exploitation. Neimenggu Chem. Ind. 2005, 3, 110–112. (3) Hyne, J. B.; Greidanus, J. W. Aquathermolysis of Heavy Oil. Proceedings of the 2nd Interntional Conference on HeaVy Crude and Tar Sands, Caracas, Venezuela, 1982; pp 25-30.. (4) Clark, P. D.; Hyne, J. B. Steam-Oil Chemical Reactions: Mechanisms for the Aquathermolysis of Heavy Oil. AOSTRA. J. Res. 1984, 1, 15–20. (5) Hyne, J. B. A Synopsis of Work on the Chemical Reactions between Water and HeaVy Oil Sands during Stimulated Steam Stimulation; AOSTRA Synopsis Report No. 50, AOSTRA: Alberta, Canada, 1986. (6) Clark, P. D.; Hyne, J. B. Studies on the Chemical Reactions of Heavy Oils under Steam Stimulation Condition. AOSTRA. J. Res. 1990, 29, 29– 39.
later research, it is found that aquathermolysis has little effect on extra-heavy oil. Because only in the presence of the injection steam, a small reduction in viscosity and little change of components of the heavy oil were seen. Hence, a number of scientists7–16 conducted a lot of research into which of various catalysts should be added to catalyze the aquathermolysis. With the aquathermolysis and catalysis, more heavy components of (7) Clark, P. D.; Hyne, J. B.; Tyrer, J. D. Chemistry of Organosulphur Compound Types Occurring in Heavy Oil Sands: 1. High Temperature Hydrolysis and Thermolysis of Tetrahydrothiophene in Relation to Steam Stimulation Processes. Fuel 1983, 62, 959–962. (8) Clark, P. D.; Hyne, J. B.; Tyrer, J. D. Some Chemistry of Organosulphur Compound Types Occurring in Heavy Oil Sands: 2. Influence of pH on the High Temperature Hydrolysis of Tetrahydrothiophene and Thiophene. Fuel 1984, 63, 125–128. (9) Clark, P. D.; Hyne, J. B.; Tyrer, J. D. Chemistry of Organosulfur Compound Type Occurring in Heavy oil Sands. 3. Reaction of Thiophene and Tetrahydrothiophene with Vanadyl and Nickel Salts. Fuel. 1984, 63, 1649–1645. (10) Clark, P. D.; Dowling, N. I.; Hyne, J. B.; Lesage, K. L. The Chemistry of Organosulphur Compound Types Occurring in Heavy Oils: 4. the High-temperature Reaction of Thiophene and Tetrahydrothiophene with Aqueous Solutions of Aluminium and First-row Transition-metal Cations. Fuel 1987, 66, 1353–1357. (11) Clark, P. D.; Dowling, N. I.; Lesage, K. L.; Hyne, J. B. Chemistry of Organosulphur Compound Types Occurring in Heavy Oil Sands: 5. Reaction of Thiophene and Tetrahydrothiophene with Aqueous Group VIIIB Metal Species at High Temperature. Fuel 1987, 66, 1699–1702. (12) McFarlane, R. A.; Cyr, T.; Hawkins, R. W. T. Process for Dispersing Transition Metal Catalytic Particles in HeaVy Oil, US Patent 5,916,432, 1999. (13) Pelrine, B. P.; Comolli, A. G.; Lee, L. K. Iron-based Ionic Liquid Catalysts for Hydroprocessing Carbonaceous Feeds. US Patent 6,139,723, 2000. (14) Soled, S. L.; Riley, K. L.; Schleicher, G. P. Hydroprocessing Using Bulk Group VIII Catalysts. US Patent 6,162,350. 2000. (15) Cordova, J.; Pereira, P.; Guition, J. Andriollo A., Cirilo A.; Granadillo F., Production of Oil Soluble Catalytic Precursors. US Patent 6,043,182. Mar 28, 2000. (16) Babcock, L. M.; Morrell, D. G. Flourinated Solid Acid as Catalysts for the Preparation of Hydrocarbon Resins. US Patent 6,281,309 B1. Aug 28, 2001.
10.1021/ef8000136 CCC: $40.75 2008 American Chemical Society Published on Web 04/22/2008
Catalytic Aquathermolysis of HeaVy Oil
the heavy oil pyrolyzed and the structure changed to a larger degree, and these changes could hardly regress and eventually reduce the viscosity of heavy oil more, benefiting oil exploitation, transportation, and upgrading. All the reactions between heavy oil, steam, and catalysts were described as “catalytic aquathermolysis”. It is evident that the key to catalytic aquathermolysis is the catalysts. Currently, the catalysts used in this technology are mostly transition metal ion salts, transition metal compounds, and some solid superacids.7–28 These catalysts in laboratory experiments showed the best viscosity reduction at a rate of about 80∼90% at 280 °C and about 75∼85% at 240 °C. In order to better the performance of these catalysts, different catalysts have been tested. First, a transition metal organic acid salt29 was synthesized and used in aquathermolysis. The experiments showed that the viscosity reduced by 97% at 280 °C. Later Keggin-HPAS30 was applied, which showed viscosity reduction above 80% at 200 °C. Both of these achievements showed great progress in laboratory study and made enormous strides for field tests, but it still had insufficiencies and was far from satisfactory. The largest gap between the laboratory and the field is the two following aspects: First, the temperature on the oil floor after steam injection gradually lowered with the increasing depth of the oil floor and is difficult to keep above 240 °C; so, there is not enough energy supplied for catalysis. Second, the catalysts are not in sufficient contact with heavy oil molecules on the oil floor, which decreased their catalytic efficiency. Hence, synthesizing a catalyst which can sufficiently contact the heavy oil and maximize its catalysis at 200 °C would be a great advance for catalytic aquathermolysis even for the exploitation of heavy oil. (17) Fan, H. F.; Liu, Y. J.; Zhao, X. F. Studies on Effect of Metal Ions on Aquathermolysis Reaction of Liaohe Heavy Oil under Steam Treatment. J. Fuel Chem. Technol. 2001, 29, 430–433. (18) Rivas, O. R.; Campos, R. E.; Borges, L. G. Experimental EValuation of Transition Metals Salt Solutions as AdditiVes in Steam RecoVery Processes, SPE 18076; Society of Petroleum Engineers, 1988539547. (19) Clark, P. D.; Kirk, M. J. Studies on the Upgrading of Bituminous Oils with Water and Transition Metal Catalysts. Energy Fuels 1994, 8, 380– 387. (20) Fan, Z. X.; Zhao, F. L.; Wang, J. Upgrading and Viscosity Reduction of Extra Heavy Oil by Aquathermolysis with Hydrogen Donor. J. Fuel Chem. Technol. 2006, 34, 315–318. (21) Wen, S. B.; Liu, Y. J.; Song, Y. W. Effect of Silicotungstic Acid on Catalytic Visbreaking of Extra Heavy Oil from Shengli Oilfield. J. Daqing Pet. Inst. 2004, 28, 25–27. (22) Liu, Y. J.; Chen, E. Y.; Wen, S. B. The Preparation and Evaluation of Oil-soluble Catalyst for Aquathermolysis of Heavy Oil. Chem. Eng. Oil Gas 2005, 34, 511–512. (23) Chen, E. Y.; Liu, Y. J.; Ge, H. J. A Study on the Degradation of the Asphaltene in Liaohe Heavy Oil during Catalytic Aquathermolysis Reaction. J. Daqing Pet. Inst. 2005, 29, 9–11. (24) Chen, E. Y.; Liu, Y. J.; Wen, S. B. A Study on the Degradation of the Resin in Liaohe Heavy Oil during Catalytic Aquathermolysis Reaction. Chem. Eng. Oil Gas 2005, 35, 49–50. (25) Fan, H. F.; Liang, T. Function of Catalysts in Hydrothermal Cracking of Heavy Oil. Ind. Catal. 2006, 14, 1–4. (26) Zou, C. J.; Huang, Z. Y.; Luo, P. Y. Oxidative Degradation of Macromolecular Constituents of Heavy Oil in [(MoO2)(acac)2]/t-BuOOH/ H3PO4 Catalyzed Oxidative Degradation System. J. Chem. Ind. Eng. (China) 2005, 56, 853-856.. (27) Zou, C. J.; Liu, C.; Huang, Z. Y. Catalyst Degradation of Macromolecular Constituents of Asphaltic Sands in Ionic Liquids. J. Chem. Ind. Eng. (China) 2004, 55, 2095–2098. (28) He, S. Z.; Fan, H. F. Viscosity and Molecular Weight Change of Heavy Oil under Steam and Metal Salts Coexistence. Chem. Eng. 2006, 8 (1-2), 9. (29) Chen, Y.; Chen, Y. L.; Zhu, M. Catalytic Effect of Organic Acid Transitional Metallic Salt on Aquathermolysis Reaction of Heavy Oil. Geol. Sci. Technol. Inf. 2005, 24, 75–79. (30) Wang, Y. Q.; Chen, Y. L.; Xia, F. Synthesis and Characterization of Keggin Heteropoly Acid Salt Used in Aquathermolysis Reaction of Heavy Oil. Geol. Sci. Technol. Inf. 2007, 26, 81–85.
Energy & Fuels, Vol. 22, No. 3, 2008 1503 Table 1. Factors and Levels of Orthogonal Experiments A
B
C
D
item
temperature (°C)
concentration of the catalyst (wt %)
W/O
pH
1 2 3 4
200 180 160 140
0.20 0.16 0.12 0.08
5:5 4:6 3:7 2.5:7.5
13 12 11 10
Table 2. Orthogonal Experiment item
A
B
C
D
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
200 200 200 200 180 180 180 180 160 160 160 160 140 140 140 140
0.20 0.16 0.12 0.08 0.20 0.16 0.12 0.08 0.20 0.16 0.12 0.08 0.20 0.16 0.12 0.08
5:5 4:6 3:7 2.5:7.5 4:6 5:5 2.5:7.5 3:7 3:7 2.5:7.5 5:5 4:6 2.5:7.5 3:7 4:6 5:5
13 12 11 10 10 11 12 13 12 13 10 11 11 10 13 12
To remedy these two insufficiencies, we designed a new type of catalyst composed of a high-active metal cation and an amphiphilic anion. The amphiphilic anion can act as both the metallic carrier and amphiphilic catalytic viscosity reducer. Unlike the conventional carrier, it has an amphiphilic group and can remarkablely reduce the interfacial tension between the oil and water. So, it can mix the oil with water more uniformly and remain on the interface of the oil and water. Hence, the metallic ions can be dispersed more evenly into the oil-water mixture and maximize its catalysis. Meanwhile, the amphiphilic anion can infiltrate into the large molecules of resin and asphaltene, influencing or even damaging their firm associating structure, breaking the close packed aggregation, and reforming a loose structural, low-ordered one. In addition, the amphiphilic anion can generally show its action at relatively lower temperature. Whether this catalyst can solve the two above problems and show good catalysis in aquathermolysis or not should be tested in the laboratory and even in the field. This paper presents our first investigation of the amphiphilic metallic chelate-aromatic sulfonic iron used in laboratory experiments of aquathermolysis of the extra-heavy oil under 200 °C and in field tests in the Henan oilfield. It evaluates the efficiency of viscosity reduction, contrasts the aquathermolytic catalysis of the new catalyst and several other ones, analyzes the changes of the contents and structures of group composition of heavy oil before and after the reaction, and reports the results of the field tests. 2. Experiment 2.1. Synthesis and Characterization of the Catalyst. Fe or Fe2O3 and a type of aromatic sulfonic acid were used to prepare the amphiphilic metallic chelate catalyst-aromatic sulfonic iron. During the synthesis, 20 g aromatic sulfonic acid was placed in a beaker which then was placed in a 100 °C oil bath for 20 min to preheat the acid. A 1.8 g Fe2O3 portion or 1.2 g Fe (the average particle size was 80-200 meshes) was added into the beaker with stirring by a magnetic polytetrafluroethylene agitator, after they interacted with each other under stirring for 2 h at 100 °C. The mixture was dissolved in 20 mL acetone and filtrated to remove the residuals. The aromatic sulfonic iron was obtained after the
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Figure 1. FT-IR spectrum of the prepared catalyst.
Figure 2. IR spectrum of asphaltene (a) before and (b) after aquathermolysis reaction.
Figure 3. IR spectrum of resin (a) before and (b) after aquathermolysis reaction.
filtrate was heat-treated in a vacuum under 50 °C for 24 h and then analyzed by Fourier transform infrared (FT-IR) spectroscopy. 2.2. Laboratory Work on Catalytic Aquathermolysis. We designed the orthogonal, single-factor experiments, and blank experiments as well as the contrast experiments to evaluate the catalytic performance. For this evaluation, some heavy oils were used in the experiments: EX35, with a viscosity of about 28 867 mPa · s; G540, 8.1 × 105 mPa · s; Y3913, 22 000 mPa · s; Zhen411,
7.9 × 105 mPa · s; Sheng2-Re7, 9.2 × 104 mPa · s, and Zhen6-Ping2, 5.2 × 105 mPa · s. All of the experiments were carried out by adding successively 120 g oil, the water (liquid) in a designed mass ratio, and the catalyst in designed mass concentration into the FYX-0.5 high pressure reactor (the volume is 500 mL). The original pressure was kept to 3 MPa by aerating N2; the pressure would rise through the reaction and reach to about 6∼7 MPa hours later, this would last to the
Catalytic Aquathermolysis of HeaVy Oil
Energy & Fuels, Vol. 22, No. 3, 2008 1505 Table 3. Contrast of Several Catalysts viscosity reduction (%)
aromatic sulfonic iron aromatic bis-Schiff base Keggin-K3PMo12O40 naphthenic acidic iron
EX35
G540
Y3913
Zhen411
Sheng2-Re7
Zhen6-Ping2
90.66 89.87 80.23 78.60
80.67 64.35 80.33 69.76
92.66 86.65 81.25 82.44
82.56 58.90 75.00 71.67
93.30 84.73 78.98 81.88
85.73 77.88 74.43 77.21
Table 4. Group Composition of EX35 Heavy Oil before and after Reaction oil sample EX35 oil EX35 oil after blank experiment EX35 oil after catalytic aquathermolysis
sat HC
aro HC
resin
asphaltene
total
% 26.97 27.84
% 14.12 15.56
% 40.86 38.67
% 18.05 17.93
% 100 100
35.4
20.35
30.42
13.83
100
time when we stopped the reaction. After the reactions went on for the designed time under the designed conditions, the mixture were taken out of the reactor to be tested and analyzed when the inside temperature of the reactor reduced to about 50 °C. The viscosity of heavy oil was recorded by the Brookfield DV-2+ programmable viscometer when it showed the torque be about 50% at 50 °C before and after the reaction. The rate of viscosity reduction was calculated by the method ∆η ) ((η0 - η)/η0) × 100, where ∆η (%) was the rate of viscosity reduction, η0 (mPa · s), the viscosity of oil before the reaction, and η (mPa · s), the viscosity of oil after the reaction. The orthogonal experiments were conducted for 24 h according to the Tables 1 and 2, which show the orthogonal experimental conditions for EX35. For every heavy oil, the experiment design was same, in which the temperature and W/O were same and the pH and the catalyst concentration were different. W/O is the mass ratio of water to oil; the pH was adjusted by adding a certain volume of the 0.1% NaOH solution. The single-factor experiments were conducted for 12, 24, 36, and 72 h under the optimum reaction conditions from the orthogonal experiments. The blank experiments were conducted under the optimum reaction conditions from the above experiments without the catalyst. The contrast experiments were conducted later, in which aromatic bis-Schiff base, KegginK3PMo12O40, and naphthenic acidic iron, which we synthesized before, were used into aquathermolysis to contrast with the aromatic sulfonic iron. Every kind of catalyst should catalyze the aquathermolyses of EX35, G540, Y3913, Zhen411, Sheng2-Re7, and Zhen6-Ping2 heavy oil at their optimum conditions. Furthermore, four group compositions including asphaltene, resin, saturated hydrocarbon and aromatic hydrocarbon were separated from EX35 by a column chromatography according to the industrial standard of China Petroleum SY/T 5119. Then, the changes of structures of resin and asphaltene were analyzed before and after the reaction with FT-IR on a Nicolet 5700 spectrometer using the KBr disk method. The element analyses for resin and asphaltene were implemented before and after the reaction on an EL-2 element analysis instrument, whereas the analyses for the reaction gas before and after the catalysis were carried out on a Saturn2200 GC/MS. 1H NMR spectra of resin and asphaltene were recorded before and
after the reaction on a Bruker ARX300 NMR spectrometer using CDCl3 as solvent, whose chemical shift is referred to the TMS standard. 2.3. Field Test. Field tests of the catalytic aquathermolysis of aromatic sulfonic iron were conducted in the Henan oilfield. G61012 and G6606 oil wells were chosen for tests. In this technology, the mass of oil is calculated according to the exploitation radius and some parameters of the oil layers like infiltration ratio, pole ratio, etc. The water was added by injecting the high temperature and pressure steam, which was adjusted to be basic by adding NaOH to make the oil floor conditions accord to the laboratory conditions. The catalyst was added into the oil floor which is used as a nature reactor at an interval when the steam was injected. They were added in the laboratory optimum ratios. The nitrogen was injected if the oil floor did not have enough pressure. The parameters of field tests were as follows: for the G61012 oil well, steam of 998 m3, and no nitrogen, was injected into the oil floor; for the G6606 oil well, steam of 1120 m3 and nitrogen of 23 000 m3 were injected. After the well was closed for 3 d, 14 d after reopening the well was determined to be a period to evaluate the field tests, the yield and the viscosity reduction ratio for a period were the most important parameters to evaluate the field tests.
3. Results and Discussion 3.1. Characterization of the Prepared Catalysts. An FTIR spectrum for the prepared catalyst was recorded, as is shown in Figure 1. The bands at 582 and 1174 cm-1 were attributed to the vibration of metallic elements and the amphiphilic groups of reactants. As a result, the prepared catalyst was in conformance with what we designed. 3.2. Results of Laboratory Study of Catalytic Aquathermolysis. 3.2.1. Laboratory Results. The orthogonal design and single-factor experiment results show a viscosity reduction of 90.66%, 80.67%, 92.66%, 82.56%, 93.30%, and 85.73%, respectively, for EX35, G540, Y3913, Zhen411, Sheng2-Re7, and Zhen6-Ping2 heavy oils at 200 °C under the optimum test conditions. (Take the EX35 for an example, its viscosity reduction was 90.66% under the condition when the temperature ) 200 °C, W/O ) 3/7, the concentration of catalyst ) 0.16 wt %, and pH ) 12). Correspondingly, the blank experiment results show a viscosity reduction of 20.32%, 10.79%, 15.56%, 8.05%, 22.30%, and 12.88%, respectively, for EX35, G540, Y3913, Zhen411, Sheng2-Re7, and Zhen6-Ping2 heavy oils in the same conditions without catalysts. The contrast of the viscosity reductions obtained in the experiments with and without catalyst proves that this catalyst should be efficient and universal. The results of the contrast experiments listed in Table 3 show the
Table 5. Element Content of Resin and Asphaltene of EX35 before and after Aquathermolysis Reaction group composition
N (wt %)
C (wt %)
S (wt %)
H (wt %)
O (wt %)
asphaltene of EX35 before aquathermolysis reaction asphaltene of EX35 after aquathermolysis reaction resin of EX35 before aquathermolysis reaction resin of EX35 after aquathermolysis reaction
2.08
82.69
0.38
11.32
3.53
1.71
85.20
0.34
12.00
0.76
1.55
78.60
0.38
10.93
8.54
1.61
84.82
0.36
12.14
1.08
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Table 6. Assignment of Protons in the 1H NMR Spectrum parameter
type of protons
chemical shifts (ppm)
HA HR
aromatic hydrogen aliphatic hydrogen on CR to aromatic rings aliphatic hydrogen on Cβ and the CH2, CH beyond the Cβ to aromatic rings Aliphatic hydrogen on Cγ and the CH3 beyond the Cγ to aromatic rings
6.0-9.0 2.0-4.0
Hβ Hγ
1.0-2.0 0.5-1.0
Table 7. 1H NMR of Resin and Asphaltene of EX35 before and after Aquathermolysis Reaction group composition
HA
HR
Hβ
Hγ
asphaltene before aquathermolysis reaction asphaltene after aquathermolysis reaction resin before aquathermolysis reaction resin after aquathermolysis reaction
0.95 2.67 1.27 4.41
6.69 8.22 0.03 8.54
64.99 59.85 63.57 62.56
27.52 29.26 35.12 24.49
superiority of the new catalyst. To every kind of heavy oil, the aromatic sulfonic iron led to the higher viscosity reduction. 3.2.2. Change of the Group Composition. Table 4 lists the group compositions of heavy oil EX35 before and after the reaction, which were determined by thin-layer chromatographyflame ionization detection (TLC-FID) according to the industrial specification of China Petroleum SY/T 6338. It can be seen that the resin decreased by 10.44% and asphaltene, by 4.22%, while the saturated and aromatic hydrocarbon increased by 8.43% and 6.23% after the catalytic aquathermolysis reaction; after the blank experiment without catalyst, the resin decreased by 2.19%, and asphaltene, by 0.12%, while the saturated and aromatic hydrocarbon increased by 0.87% and 1.44%. The comparison of results of the reactions with and without catalyst verifies that the catalyst could catalyze the heavy content (asphaltene and resin) to pyrolyze to the light content (sat HC + aro HC). 3.2.3. Element Analysis of Resin and Asphaltene before and after the Reaction. The results for elemental analysis (EL) are listed in Table 5. After calculation, the ratioa of hydrogen to carbon were obtained as follows: NH/NC (asphaltene before aquathermolysis reaction) ) 1.64, NH/NC (asphaltene after aquathermolysis reaction) ) 1.69, NH/NC (resin before aquathermolysis reaction) ) 1.67, NH/NC (resin before aquathermolysis reaction) ) 1.72. Obviously, the increase of the asphaltene and resin saturation and the decrease of their aromaticity illustrate the probable hydrosilylation during the reaction. Moreover, the
Figure 5. 1H NMR spectrum of asphaltene after aquathermolysis.
Figure 6. 1H NMR spectrum of resin before aquathermolysis.
Figure 7. 1HNMR spectrum of resin after aquathermolysis.
Figure 4. 1H NMR spectrum of asphaltene before aquathermolysis.
evident reduction of oxygen of asphaltene and resin after aquathermolysis reaction indicates the pyrolysis of C-O bonds. 3.2.4. FT-IR Spectra of Resin and Asphaltene before and after the Reaction. Figure 2 exhibits the IR spectrum of asphaltene before and after the reaction. The bands at 1730.7, 1282.8, 1121.5, and 1072.6 cm-1 disappeared while 1034.6, 866.8, and 811.0 cm-1 appeared. In the IR spectrum, the band at 1730.7 cm-1 was assigned to the aldehydes CdO stretch, and 1282, 1121, 1072, and 1034 cm-1, to amines C-N stretch, the C-O stretch belonging to alcohols, esters, ethers, carboxyl, and anhydrides, or SdO belonging to sulfones, sulfonyl,
Catalytic Aquathermolysis of HeaVy Oil
Energy & Fuels, Vol. 22, No. 3, 2008 1507
Table 8. Aromaticity fA and Aromaticity Condensation HAU/CA of Asphaltene and Resin of EX35 before and after Aquathermolysis Reaction
fA HAU/CA
asphaltene before aquathermolysis reaction
asphaltene after aquathermolysis reaction
resin before aquathermolysis reaction
resin after aquathermolysis reaction
0.19 0.38
0.18 0.65
0.18 0.12
0.18 0.84
chlorides, sulfates, and sulonamides. The bands at 868 and 811 cm-1 showed the aromatic C-H out-of-plane bend-stretch. All these changes indicated the probable pyrolysis of CdO, C-N, C-O, and SdO. A combination of this result with the result of the element analysis suggests that the pyrolysis of C-O and CdO were predominant during the reaction. Figure 3 exhibits the IR spectrum of resin before and after the reaction. The unobvious change was probably due to the simultaneous reactions of the polymerization and pyrolysis in the catalytic aquaqthermolysis. This was because the degrees of the polymerization and pyrolysis, which were contemporaneous and competitive in aquathermolysis, were equal.31 3.2.5. 1H NMR of Resin and Asphaltene before and after Aquathermolysis Reaction. The 1H NMR results for resin and asphaltene of EX35 before and after the aquathermolysis reaction can be seen in Tables 6-8 and Figures 4-7. Aromaticity fA and aromaticity condensation HAU/CA were obtained by formulas 1 and 2: CT/HT - (HR + Hβ + Hγ)/2HT CT/HT
(1)
HA/HT + HR/2HT HAU ) CA CT/HT - (HR + Hβ + Hγ)/2HT
(2)
fA )
In formulas 1 and 2, CT and HT represent the total carbon and hydrogen respectively, HT ) HA + HR + Hβ + Hγ; CT/HT is the ratio of carbon to hydrogen, and the assumed date of CT/ HT of saturated composition equals 2. In formula 2, the larger HAU/CA, the lower aromaticity condensation. The results are shown in Table 5. It is not difficult to see from Table 5 that the aromaticity and aromaticity condensation of asphaltene and resin decreased after aquathermolysis. The decrease of the former could be attributed to hydrosilylation of unsaturated groups while that of the latter could be caused by the ring-opening and reconstruction of the aromatic system by catalysis. 3.2.6. GC/MS of Pyrolytic Gas before and after Catalysis. The GC/MS analysis reveals the appearance of new peaks and the obvious increase of some original peaks. This demon-
Figure 8. Production parameters of G61012.
strates that new small gas molecules such as alcohol, phenolic, olefin, alkane, and ether appeared after catalysis in the aquathermolysis reaction. This results further clarify the pyrolyses of C-C, C-O, and C-S bonds. From above results and discussion, the aromatic sulfonic iron mainly reacts to the heteroatoms of the heavy oil molecules such as S, N, and O, especially for O, and breaks, as a consequence, the C-R (R ) S, N, O), the hydrogen bond from the heteroatoms, and the strongly associating action from the complex made of heteroatoms and micrometallic atoms successively. Meanwhile, this catalyst can also react to the infirm covalent bonds and make them pyrolyzed. These actions led to the pyrolysis of side-chains and bridge-chains and catalyzed C-R to produce some small gas molecules such as sulfureted hydrogens, alcohols, hydroxybenzenes, ethers, alkenes, alkyls, etc. Besides, the aromatic sulfonic acid anion can infiltrate into the large molecules of the resin and asphaltene, breaking their firm associating structure and the close packed aggregation, reforming a loose structural, low-ordered one. All of these actions can be illustrated by the following reaction: aquathermolytic catalysis
heavy oil + water 98 large molecule + (firm, close packed)
aromatic sulfonic iron
small molecule + (hydrocarbon,furan, thiophene,pyridine)
(loose, low-order)
gas
(sulferetedhydrogens,alkenes,alkyls, alcohols,ethers,hydroxybenzenes)
+ H2O
3.3. Results of Field Tests of Catalytic Aquathermolysis. The production parameters of the G61012 and G6606 oil wells can be seen in Figures 8 and 9. It is not difficult to see that, for G61012, the addition of production was 188.7 t in a period, the viscosity reduction was 79.66%, the ratio of oil to steam increased by 0.12, and the ratio of production to injection increased by 0.26 and that, for G6606, the addition of production was 217 t, the viscosity reduction was 82.25%, the ratio of oil to steam increased by 0.15, and the ratio of production to injection increased by 0.28, respectively. The results showed the evident effect of aquathermolysis technology, and the
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Figure 9. Production parameters of G6606.
aromatic sulfonic iron was a good aquathermolytic catalyst for exploitation of heavy oil. 4. Conclusion To sum up, the new catalyst aromatic sulfonic iron shows evident viscosity reduction. With its presence, the viscosities of heavy oils EX35, G540, Y3913, Zhen411, Sheng2-Re7, and Zhen6-Ping2 reduce at a rate of 90.66%, 80.67%, 92.66%, 82.56%, 93.30%, and 85.73%, respectively, at 200 °C in the optimum test conditions. This new catalyst also shows its superiority on viscosity reduction after comparison with several other efficient ones. Further analysis of EX35 shows that the heavy content was transfered to the light content at a rate of 14.66% in aquathermolysis and also proves that the compositions and structures of heavy oil have partly changed and that this change should lead to the (31) Liu, Y. J.; Zhong, L. G.; Jiang, S. J. Research Progress of Recovering Heavy Oil by Aquathermolysis. J. Fuel Chem. Technol. 2004, 32, 117–122.
viscosity reduction. In addition, the results of field tests show the evident effect of aromatic sulfonic iron in the aquathermolysis of G61012 and G6606 wells in the Henan oilfield. The production increased by 188.7 t in 14 d after the use of catalytic aquathermolysis technology, the viscosity reduced at a rate of 79.66% for G61012, and those values were 217 t and 82.25% for G6606. The results of both the laboratory experiments and the field tests demonstrate that aquathermolytic catalysis is effective for extra-heavy oil and prove that the aromatic sulfonic iron is a type of good catalyst in aquathermolysis for extra-heavy oil. Acknowledgment. The authors would like to thank Chen G. E, Xu G. Jun, and Hou A. Xin for FT-IR, TLC-FID, and 1H NMR characterization. We also are thankful for the financial support from the nature science foundation and for the technical support from the key laboratory-catalytic material sciences laboratory of the South-Central University of Nationalities. EF8000136
