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Possible contribution of carbon dioxide flooding to global environmental issues
Energy Convers. Mgmt Vol. 33, No. 5-8, pp. 587-593, 1992
0196-8904/92 $5.00+0.00 Copyright © 1992 Pergamon Press Ltd
Printed in Great Britain. All rights reserved
POSSIBLE C O N T R I B U T I O N OF CARBON D I O X I D E F L O O D I N G T O G L O B A L E N V I R O N M E N T A L ISSUES
S. Tanaka, The University of Tokyo, Japan T. Hakuta, National Chemical Laboratory for Industry, Ibaragi, Japan H. Haino, Engineering Advancement Association of Japan, Tokyo, Japan ENGINEERING ADVANCEMENT ASSOCIATION OF JAPAN (ENAA) Takagi Bldg., 7-2, Nishi-Shimbashi 1-chome, Minato-ku, Tokyo 105, Japan
ABSTRACT The problem of global wanning illustrates the serious interrelationship between the production of energy and environmental concerns. As part of the survey on the effective use of carbon dioxide, taking the global environment into consideration, a study was carded out on the application of CO2 in EOR as a countermeasure to global warming. This paper studies the feasibility of a total system for the stabilization of CO2 using EOR. This system involves separation and recovery of CO2 from fixed sources in Japan, liquefaction and transportation to the oil-fields in oil producing countries, injection to the reservoir and eventual recovery and recycling. Utilization of CO2 for EOR therefore, not only increases oil production but also results in the stabilization of CO2, thus preventing further global wanning. KEYWORDS Carbon Dioxide, Exhaust Gases, Enhanced Oil Recovery, Carbon Dioxide Injection, Carbon Dioxide Recycling PREFACE Global environmental problems can scarcely afford to wait for countermeasures to be formulated after scientific evidence of their causes is obtained. Practicable measures need to be implemented immediately. Even in the 21st century, energy, information, food and the environment will continue to be major issues that are interrelated. Among these, the environment has drawn much attention as the central issue, while energy is an issue that is closely related to the environment. Like other major countries, it is believed that Japan will continue to be dependent on oil and natural gas in the next century. Oil and natural gas are vital, not only as energy but also as industrial raw materials. Disposing of such resources in the form of carbon dioxide gas or plastic goods should be avoided for future generations. A recycle system which can regenerate such resources, will be required in the future. From this standpoint, a system that stabilizes carbon dioxide in a usable form is highly desirable. Carbon dioxide is commonly used in today's industries. One use is in the field of enhanced oil recovery (EOR) as carbon dioxide flooding (CO2 flooding). In the U.S., which is the advanced nation on EOR, the number of CO2 flooding projects is on the increase. The flooding is currently studied only from the standpoint of increasing oil production. In addition to this point, this study considers the CO2 flooding from a different angle of prevention of global warming by reducing emission of carbon dioxide to the atmosphere. The study was started in 1990 and conducted by experts in each company, after the Engineering Advancement Association of Japan contracted with the New Energy and Industrial Technology Development Organization (NEDO). The paper is a summary of the first year activity, and a more detailed study is being conducted now.
587
588
TANAKA et al.:
POSSIBILITIES OF CO 2 FLOODING
1, COs Emission~ Japan's CO2 emissions stood at approximately 280 million tonnes C (1,010 million tonnes of CO2) as of 1988, accounting for 4.7% of the entire world's emissions, which totaled 5,890 million tons C. Manufacturing and electric power-related industries represent about 60% of domestic CO2 emissions. These industries constitute fixed sources of emission. Since these sources are compact and closely related, CO2 can be recovered. However, it will be difficult to do so for other sources of emission (Figure- 1). Electric Power l
36.9~ Others
House Us
38.8~ iron Works
7.6~ Cement Plant 16.8X Petrochemical Plant
Fig. 1 Carbon Dioxide Sources in Japan (1986)
The majority of exhaust gases from these fixed sources of emission are produced as a result of buming fossil fuel. As part of the countermeasures against CO2-caused global warming, a wide range of industries centering on electric power companies are mounting efforts to make the recovery of CO2 from these combustion exhaust gases larger, more energy-conserving and cost efficient. 2. Status of EOR Usin~ Carbon Dioxide EOR is sometimes referred to as a tertiary recovery method, which recovers crude oil remaining in the oil reservoir after primary recovery by natural flow and secondary recovery by water flooding are performed. There are various EOR methods which are expected to show promise in raising the recovery of crude oil in the future: thermal, chemical, gas and other floodings. Carbon dioxide flooding is classified as one of the gas flooding methods. Among these methods, CO2 flooding is currently being widely used, particularly in the U.S. In 1990, this method contributed to a 100,000-barrels-a-day increase in crude oil production (Moritis, 1990). CO2 flooding is being performed primarily in the western part of Texas. CO2 is supplied to oil fields through a pipeline from CO2 gas fields developed in Colorado and New Mexico. In the U.S., the number of projects related to EOR using CO2 and the increase in oil production have been rising despite the drop in crude oil prices in the past several years. 3, Stabilization ofCO~ osin~ EOR and Estimation of Stabilizable Amount When CO2 injects into a reservoir under high pressure, the CO2 makes a miscible zone with reservoir oil, and pushs oil into the production well. A portion of the CO2 injected into the reservoir is produced with the oil at the surface as associated gas. The associated gas is released from the oil, and then separated into hydrocarbon gas and CO2. The recovered CO2 is reinjected into the reservoir (Figure-2). A completely closed system is created in this manner. Several large-scale CO2 recycling plants operate in the western part of Texas. These plants do not emit CO2 into the atmosphere, but store it in the oil reservoir. Since an impermeable layer always exists in the top part of the oil reservoir, crude oil and gas accumulates there over a period of millions of years. It can be said that the oil reservoir guarantees the prevention of CO2 leakage.
TANAKAet al.: POSSIBILITIESOF CO2 FLOODING
589
We computed the stabilizable amount of CO2 by estimating the amount of CO2 required for EOR. The estimation is carried out with data deduced from published papers (see Appendix). Based on such data, the amount of CO2 required for EOR worldwide is estimated at about 63.0 billion tonnes. It should be noted that this figure represents the total amount of CO2 required and that this is not the amount currently required. Also, it should be kept in mind that the Middle East accounts for roughly 50% of this amount. Further, this amount is expected to increase dramatically if the technology of CO2 flooding is improved from the standpoint of CO2 stabilization. C02 Recover,/ I CO 2 Recycle
>Natural Gas
T
Compresso~
Oi I/Gas Separat I on
>Crude 011
CO2fromoutside C02 InjectioJ Puma
C02Injectloe Well
Production
,'02 njection Well
Well
f f
oi,/co -41
~
ReservJor /
/
Fig. 2 Carbon Dioxide Injection and Recycling System
4. Total System Figure-3 and Table-1 describe the CO2 flooding total system for preventing global warming caused by CO2, as studied in this survey.
Middle
East
,,-~~
Japan ~ixed Sources
~'~
Oil ProducingCountry
SoutheastAsia
Liquid CO 2 Tanker
Fig. 3 Total System of EOR Using Carbon Dioxide from Flue Gas
6,336
CO2 Capacity
Note
.
-
Gas Production(MMSCF/da~)
(%)
CO2 Recovery Ratio
100
.
('C)
CO2 Temperature
1.03
(BBL/day)
(ata)
CO2 Pressure
EOR Capacity
(%)
CO2 Purity
8.55
6,336
Capacity of the Train (tonnes/day)
(tonnes/day)
19,008
2
Capacity of the Works (tonnes/day)
Number of Works
Fixed Source
Consid¢~ Chemical Absorption
.
.
90
50
1.3
99.9
5,882
5,882
17,646
2
CO2 Recovery
.
.
.
-50
7.0
99.9
5,882
5,882
17,646
2
CO2 Liquefaction
.
. .
.
CO2 Tank 20,000m 3 x 8
.
-50
7.0
99.9
32,000
32,000
32,000
1
COz Storage & Shipping
.
.
.
Southeast Asia 20 days/voyage Middle East 38 days/voyage
.
-50
7.0
99.9
32,000
80,000 (80,000)
9 (17)
-
CO2 Tanker
Table 1. Total System Study Base
CO 2 Tank 20,000m3 x 8
.
.
.
-50
7.0
99.9
32,00
32,000
32,000
1
CO~zReceiving
6MSCF/BBL
.
-50
180
99.9
32,000
6,400
32,000
1
COz Injection
GOR 3MSCF/BBL (COz: 2MSCF/BBL, H.C.Gas: 1MSCF/BBL)
300
100,000
50
10
66.7
10,510
10,510
10,510
I
Oil/Gas Production
CO~z Recovery: Membrane and Absorption Method 2MSCF/BBL
-
-
98
50
180
95.0
10,300
10,300
10,300
1
CO2 Recycling
¢~
~5
o~ O "n
o~
..
>
,.-1 > Z
TANAKA et aL: POSSIBILITIES,OF CO2 FLOODING
591
An enormous amount of CO2 is required for the aforesaid countermeasures. Thus, oil fields in Japan cannot be expected to make a great contribution toward such efforts. For this reason, it will be necessary to transport CO2 from Japan to oil-producing countries, in a direction opposite to the transportation route of crude oil. It is anticipated this will be to regions of SoUtheast Asia and Middle East. In order to ship CO2 to oil-producing countries, the CO2 is first separated and recovered from combustion exhaust gas and then liquefied. The liquefied CO2 is then transported by CO2 tankers and unloaded at oil producing countries. After the CO2 is transported to the oil fields through a pipeline, it is injected using pumps into the reservoirs. In the oil fields, crude oil production increases as CO2 is injected. With the passage of time, CO2 dissolved in the crude oil is produced at the surface. This CO2 is recycled into the reservoir as mentioned above. We conducted a case study on a 42,300 tonnes/day CO2 injecting system, in which an amount of 32,000 tonnes/day CO2 is carried from Japan, with remaining 10,300 tonnes/day CO2 being the recycled amount at the field. This amount of CO2 from Japan is equivalent to the amount of CO2 emitted by seven 600,000 kW LNG-firing boilers or four 600,000 kW coal-firing boilers. If an 80,000 tonnes tanker is used to transport this amount of liquid CO2, 9 such tankers will be required to transport this CO2 to Southeast Asia and 17 to Middle East. Further, by injecting the net amount of 32,000 tonnes of CO2 a day into the oil fields, it is likely that crude oil production can be increased by 100,000 barrels a day. 5. Economic Viability of Total System Table-2 shows the economic viability of the total system in terms of the cost of CO2 evaluated at the current price basis in Japan. As seen in the table, the cost of recovering and liquefying CO2 from fixed sources of emission on land and the cost of shipping CO2 occupy the largest shares in the cost of CO2 to be supplied to oil fields for EOR. Table 2.
Delivered Cost of CO2 at the field
Southeast Asia
(Unit: Yen/tonnes CO2) Middle East
4,000 ~ 8,000
4,000 ~ 8,000
2,600
2,600
450
450
4,000
7,500
CO2 Receiving
500
500
CO2 Transferring to the Field
350
350
11,900 ~ 15,900
15,400 ~ 19,400
3,300
3,300
CO2 Recovery CO2 Liquefaction CO2 Storage CO2 Sea Transportation
Total CO2 Cost from Japan Recycle CO2 Cost
The cost of recovering and liquefying CO2 in Japan, transportation to Southeast Asia and injection into oil fields there, totals to ¥11,900-15,900 a tonne. This cost is ¥15,400-19,400 a tonne for Middle East. This compares with ¥3,300-6,600 per tonne of CO2 used in EOR in the U.S. Considering today's crude oil prices, this total system is not economically viable. However, when this system is treated as a countermeasure against global warming caused by COz, i.e. if the cost of CO2 to be recovered, liquefied from fixed sources and stored in Japan is financed by such financial sources as a CO2 tax, the cost of COz, from shipment to injection, amounts to ¥5,200 a tonne to Southeast Asia and ¥8,250 a tonne to Middle East. Since this cost falls within the range of the cost of CO2 in the U.S. in the case of Southeast Asia, the total system studied in this survey is believed to be economically viable. Further, if crude oil prices go up, the economic viability of this total system increases. Naturally, when industrial sources of CO2 are near oil-producing countries, the distance of transportation is short, and the economical viability becomes more reliable.
592
TANAKA et
al.:
POSSIBILITIESOF CO2 FLOODING
6. Feasibility. and Technical Issues As a result of the study, the total system studied in this survey can be adequately handled by combining existing technologies. It has also been confirmed that the individual technologies have already been implemented, primarily in the U.S. Considering the amount of CO2 emissions (1,010 million tonnes a year) in Japan today and the demand for CO2 for EOR expected in the near future, EOR using CO2 (CO2 flooding) can be regarded as one of the leading countermeasures against global warming. Table-3 presents the technical tasks picked out from the study. Current technologies can adequately cope with the aforesaid problems. However, in general, issues such as energy conservation and cost reduction remain to be addressed. With regard to individual technical items, there are numerous technical factors that need to be developed by undergoing pilot tests at each oil field while establishing a solid performance. Commercial projects cannot be implemented without preparation. It is necessary to implement feasibility studies before commercialization. Since the total system will involve oil-producing countries, cooperation with these countries is indispensable. Table 3 Technical Tasks Item • CO2 Recovery
• CO2 Liquefaction • CO2 Storage, Shipping • CO2 Ship • CO2 Receiving, Transferring, Injection • CO2 Recycling •
CO2 EOR
Task Enlargement • Minimize Energy Consumption • CO2 Recovery from Dirty Gasses • Alternative of R22 • Effective Utilization of LNG Cold Energy • Enlargementof Liquid CO2 Tank •
General Task • Minimize Energy Consumption • Cost Down • Study the Priority of the Project of Each CO2 Source
• Ditto • Ditto
• Extend the life of Membrane • Optimize C02Recovery Process • Pilot Test for Each Oil Field • IncreaseEOR Efficiency
7, Conclusion As a countermeasure against global warming, EOR using CO2 (CO2 flooding) contributes to the stabilization of CO2 and increases crude oil production. For these reasons, EOR not only effectively produce oil, but also plays a role in the storing of CO2. In the future, it will be most desirable if CO2 can be extracted as industrial resources from reservoirs flooded by CO2. REFERENCES Moritis, G. (1990). CO2 and HC injection lead EOR production increase. In: Oil & Gas Journal, April 23, pp.49-82. APPENDIX Potential cumulative requirement on carbon dioxide for EOR of 63 billion tonnes CO2 all over the world is roughly estimated as a following way. A) Discovered oil in-place is estimated at 4,500 billion barrels. (R.E. Roadifer estimated 4,740 billions in his paper of OGJ, Feb. 24, 1986).
TANAKA et al.: POSSIBILITIESOF CO2 FLOODING
593
B) Oil for CO2 flooding is assumed to be lighter than 25 API from O. Moritis report on EOR (OOJ, April 23, 1990). C.D. Masters et al. submitted worldwide and regional distributions of crude oil API gravity to World Petroleum Congress (1987). They estimated that 89% ofoil fell in the range~ C) Van Poolen (1980) pointed out that it is necessary to be deeper than 2,500 ft to attain miscible conditions. From G. Moritis report (1990). 82% of CO2 flooding fell in depth range of 3,00011,000 ft. Depth distribution of oil was shown in M.T. Halbouty's AAPG Memoir 40 (1986). This is for giant or super giant fields, but there is no other data. It showed that 90% of fields fell in the range. D) NPC report (1984) said that CO2 share was 30% of EOR in the U.S. From above mentioned screenings of B and C, it is estimated that 54% of oil in the U.S. become to be candidates for CO2 flooding. An adoption factor is introduced to reflect company's preference for CO2 flooding. In the U.S., the factor is estimated at 56% (=30/54). The factor of 56% is assumed to be applied everywhere. E) An increases in oil recovery by EOR is estimated at 10% ofoil in-place. F) Target of CO2 flooding is obtained as follows: 4,500 billions x 0.89 × 0.90 x 0.56 x 0.1 = 200 billions oil G) An average amount of CO2 from outside into oil fields is estimated at 6 MSCF/STB from W.R. Brock et al. (SPE 18977, 1990). H) The weight of 1MSCF CO2 is equivalent to 52.6kg. I ) Potential cumulative requirement on CO2 for EOR is estimated as follows: 200 billion oil x 6 x 52.6 / 1000 = 63 billion tonnes
EC'~4 33-~f1*--v
0196-8904/92 $5.00+0.00 Copyright © 1992 Pergamon Press Ltd
Printed in Great Britain. All rights reserved
POSSIBLE C O N T R I B U T I O N OF CARBON D I O X I D E F L O O D I N G T O G L O B A L E N V I R O N M E N T A L ISSUES
S. Tanaka, The University of Tokyo, Japan T. Hakuta, National Chemical Laboratory for Industry, Ibaragi, Japan H. Haino, Engineering Advancement Association of Japan, Tokyo, Japan ENGINEERING ADVANCEMENT ASSOCIATION OF JAPAN (ENAA) Takagi Bldg., 7-2, Nishi-Shimbashi 1-chome, Minato-ku, Tokyo 105, Japan
ABSTRACT The problem of global wanning illustrates the serious interrelationship between the production of energy and environmental concerns. As part of the survey on the effective use of carbon dioxide, taking the global environment into consideration, a study was carded out on the application of CO2 in EOR as a countermeasure to global warming. This paper studies the feasibility of a total system for the stabilization of CO2 using EOR. This system involves separation and recovery of CO2 from fixed sources in Japan, liquefaction and transportation to the oil-fields in oil producing countries, injection to the reservoir and eventual recovery and recycling. Utilization of CO2 for EOR therefore, not only increases oil production but also results in the stabilization of CO2, thus preventing further global wanning. KEYWORDS Carbon Dioxide, Exhaust Gases, Enhanced Oil Recovery, Carbon Dioxide Injection, Carbon Dioxide Recycling PREFACE Global environmental problems can scarcely afford to wait for countermeasures to be formulated after scientific evidence of their causes is obtained. Practicable measures need to be implemented immediately. Even in the 21st century, energy, information, food and the environment will continue to be major issues that are interrelated. Among these, the environment has drawn much attention as the central issue, while energy is an issue that is closely related to the environment. Like other major countries, it is believed that Japan will continue to be dependent on oil and natural gas in the next century. Oil and natural gas are vital, not only as energy but also as industrial raw materials. Disposing of such resources in the form of carbon dioxide gas or plastic goods should be avoided for future generations. A recycle system which can regenerate such resources, will be required in the future. From this standpoint, a system that stabilizes carbon dioxide in a usable form is highly desirable. Carbon dioxide is commonly used in today's industries. One use is in the field of enhanced oil recovery (EOR) as carbon dioxide flooding (CO2 flooding). In the U.S., which is the advanced nation on EOR, the number of CO2 flooding projects is on the increase. The flooding is currently studied only from the standpoint of increasing oil production. In addition to this point, this study considers the CO2 flooding from a different angle of prevention of global warming by reducing emission of carbon dioxide to the atmosphere. The study was started in 1990 and conducted by experts in each company, after the Engineering Advancement Association of Japan contracted with the New Energy and Industrial Technology Development Organization (NEDO). The paper is a summary of the first year activity, and a more detailed study is being conducted now.
587
588
TANAKA et al.:
POSSIBILITIES OF CO 2 FLOODING
1, COs Emission~ Japan's CO2 emissions stood at approximately 280 million tonnes C (1,010 million tonnes of CO2) as of 1988, accounting for 4.7% of the entire world's emissions, which totaled 5,890 million tons C. Manufacturing and electric power-related industries represent about 60% of domestic CO2 emissions. These industries constitute fixed sources of emission. Since these sources are compact and closely related, CO2 can be recovered. However, it will be difficult to do so for other sources of emission (Figure- 1). Electric Power l
36.9~ Others
House Us
38.8~ iron Works
7.6~ Cement Plant 16.8X Petrochemical Plant
Fig. 1 Carbon Dioxide Sources in Japan (1986)
The majority of exhaust gases from these fixed sources of emission are produced as a result of buming fossil fuel. As part of the countermeasures against CO2-caused global warming, a wide range of industries centering on electric power companies are mounting efforts to make the recovery of CO2 from these combustion exhaust gases larger, more energy-conserving and cost efficient. 2. Status of EOR Usin~ Carbon Dioxide EOR is sometimes referred to as a tertiary recovery method, which recovers crude oil remaining in the oil reservoir after primary recovery by natural flow and secondary recovery by water flooding are performed. There are various EOR methods which are expected to show promise in raising the recovery of crude oil in the future: thermal, chemical, gas and other floodings. Carbon dioxide flooding is classified as one of the gas flooding methods. Among these methods, CO2 flooding is currently being widely used, particularly in the U.S. In 1990, this method contributed to a 100,000-barrels-a-day increase in crude oil production (Moritis, 1990). CO2 flooding is being performed primarily in the western part of Texas. CO2 is supplied to oil fields through a pipeline from CO2 gas fields developed in Colorado and New Mexico. In the U.S., the number of projects related to EOR using CO2 and the increase in oil production have been rising despite the drop in crude oil prices in the past several years. 3, Stabilization ofCO~ osin~ EOR and Estimation of Stabilizable Amount When CO2 injects into a reservoir under high pressure, the CO2 makes a miscible zone with reservoir oil, and pushs oil into the production well. A portion of the CO2 injected into the reservoir is produced with the oil at the surface as associated gas. The associated gas is released from the oil, and then separated into hydrocarbon gas and CO2. The recovered CO2 is reinjected into the reservoir (Figure-2). A completely closed system is created in this manner. Several large-scale CO2 recycling plants operate in the western part of Texas. These plants do not emit CO2 into the atmosphere, but store it in the oil reservoir. Since an impermeable layer always exists in the top part of the oil reservoir, crude oil and gas accumulates there over a period of millions of years. It can be said that the oil reservoir guarantees the prevention of CO2 leakage.
TANAKAet al.: POSSIBILITIESOF CO2 FLOODING
589
We computed the stabilizable amount of CO2 by estimating the amount of CO2 required for EOR. The estimation is carried out with data deduced from published papers (see Appendix). Based on such data, the amount of CO2 required for EOR worldwide is estimated at about 63.0 billion tonnes. It should be noted that this figure represents the total amount of CO2 required and that this is not the amount currently required. Also, it should be kept in mind that the Middle East accounts for roughly 50% of this amount. Further, this amount is expected to increase dramatically if the technology of CO2 flooding is improved from the standpoint of CO2 stabilization. C02 Recover,/ I CO 2 Recycle
>Natural Gas
T
Compresso~
Oi I/Gas Separat I on
>Crude 011
CO2fromoutside C02 InjectioJ Puma
C02Injectloe Well
Production
,'02 njection Well
Well
f f
oi,/co -41
~
ReservJor /
/
Fig. 2 Carbon Dioxide Injection and Recycling System
4. Total System Figure-3 and Table-1 describe the CO2 flooding total system for preventing global warming caused by CO2, as studied in this survey.
Middle
East
,,-~~
Japan ~ixed Sources
~'~
Oil ProducingCountry
SoutheastAsia
Liquid CO 2 Tanker
Fig. 3 Total System of EOR Using Carbon Dioxide from Flue Gas
6,336
CO2 Capacity
Note
.
-
Gas Production(MMSCF/da~)
(%)
CO2 Recovery Ratio
100
.
('C)
CO2 Temperature
1.03
(BBL/day)
(ata)
CO2 Pressure
EOR Capacity
(%)
CO2 Purity
8.55
6,336
Capacity of the Train (tonnes/day)
(tonnes/day)
19,008
2
Capacity of the Works (tonnes/day)
Number of Works
Fixed Source
Consid¢~ Chemical Absorption
.
.
90
50
1.3
99.9
5,882
5,882
17,646
2
CO2 Recovery
.
.
.
-50
7.0
99.9
5,882
5,882
17,646
2
CO2 Liquefaction
.
. .
.
CO2 Tank 20,000m 3 x 8
.
-50
7.0
99.9
32,000
32,000
32,000
1
COz Storage & Shipping
.
.
.
Southeast Asia 20 days/voyage Middle East 38 days/voyage
.
-50
7.0
99.9
32,000
80,000 (80,000)
9 (17)
-
CO2 Tanker
Table 1. Total System Study Base
CO 2 Tank 20,000m3 x 8
.
.
.
-50
7.0
99.9
32,00
32,000
32,000
1
CO~zReceiving
6MSCF/BBL
.
-50
180
99.9
32,000
6,400
32,000
1
COz Injection
GOR 3MSCF/BBL (COz: 2MSCF/BBL, H.C.Gas: 1MSCF/BBL)
300
100,000
50
10
66.7
10,510
10,510
10,510
I
Oil/Gas Production
CO~z Recovery: Membrane and Absorption Method 2MSCF/BBL
-
-
98
50
180
95.0
10,300
10,300
10,300
1
CO2 Recycling
¢~
~5
o~ O "n
o~
..
>
,.-1 > Z
TANAKA et aL: POSSIBILITIES,OF CO2 FLOODING
591
An enormous amount of CO2 is required for the aforesaid countermeasures. Thus, oil fields in Japan cannot be expected to make a great contribution toward such efforts. For this reason, it will be necessary to transport CO2 from Japan to oil-producing countries, in a direction opposite to the transportation route of crude oil. It is anticipated this will be to regions of SoUtheast Asia and Middle East. In order to ship CO2 to oil-producing countries, the CO2 is first separated and recovered from combustion exhaust gas and then liquefied. The liquefied CO2 is then transported by CO2 tankers and unloaded at oil producing countries. After the CO2 is transported to the oil fields through a pipeline, it is injected using pumps into the reservoirs. In the oil fields, crude oil production increases as CO2 is injected. With the passage of time, CO2 dissolved in the crude oil is produced at the surface. This CO2 is recycled into the reservoir as mentioned above. We conducted a case study on a 42,300 tonnes/day CO2 injecting system, in which an amount of 32,000 tonnes/day CO2 is carried from Japan, with remaining 10,300 tonnes/day CO2 being the recycled amount at the field. This amount of CO2 from Japan is equivalent to the amount of CO2 emitted by seven 600,000 kW LNG-firing boilers or four 600,000 kW coal-firing boilers. If an 80,000 tonnes tanker is used to transport this amount of liquid CO2, 9 such tankers will be required to transport this CO2 to Southeast Asia and 17 to Middle East. Further, by injecting the net amount of 32,000 tonnes of CO2 a day into the oil fields, it is likely that crude oil production can be increased by 100,000 barrels a day. 5. Economic Viability of Total System Table-2 shows the economic viability of the total system in terms of the cost of CO2 evaluated at the current price basis in Japan. As seen in the table, the cost of recovering and liquefying CO2 from fixed sources of emission on land and the cost of shipping CO2 occupy the largest shares in the cost of CO2 to be supplied to oil fields for EOR. Table 2.
Delivered Cost of CO2 at the field
Southeast Asia
(Unit: Yen/tonnes CO2) Middle East
4,000 ~ 8,000
4,000 ~ 8,000
2,600
2,600
450
450
4,000
7,500
CO2 Receiving
500
500
CO2 Transferring to the Field
350
350
11,900 ~ 15,900
15,400 ~ 19,400
3,300
3,300
CO2 Recovery CO2 Liquefaction CO2 Storage CO2 Sea Transportation
Total CO2 Cost from Japan Recycle CO2 Cost
The cost of recovering and liquefying CO2 in Japan, transportation to Southeast Asia and injection into oil fields there, totals to ¥11,900-15,900 a tonne. This cost is ¥15,400-19,400 a tonne for Middle East. This compares with ¥3,300-6,600 per tonne of CO2 used in EOR in the U.S. Considering today's crude oil prices, this total system is not economically viable. However, when this system is treated as a countermeasure against global warming caused by COz, i.e. if the cost of CO2 to be recovered, liquefied from fixed sources and stored in Japan is financed by such financial sources as a CO2 tax, the cost of COz, from shipment to injection, amounts to ¥5,200 a tonne to Southeast Asia and ¥8,250 a tonne to Middle East. Since this cost falls within the range of the cost of CO2 in the U.S. in the case of Southeast Asia, the total system studied in this survey is believed to be economically viable. Further, if crude oil prices go up, the economic viability of this total system increases. Naturally, when industrial sources of CO2 are near oil-producing countries, the distance of transportation is short, and the economical viability becomes more reliable.
592
TANAKA et
al.:
POSSIBILITIESOF CO2 FLOODING
6. Feasibility. and Technical Issues As a result of the study, the total system studied in this survey can be adequately handled by combining existing technologies. It has also been confirmed that the individual technologies have already been implemented, primarily in the U.S. Considering the amount of CO2 emissions (1,010 million tonnes a year) in Japan today and the demand for CO2 for EOR expected in the near future, EOR using CO2 (CO2 flooding) can be regarded as one of the leading countermeasures against global warming. Table-3 presents the technical tasks picked out from the study. Current technologies can adequately cope with the aforesaid problems. However, in general, issues such as energy conservation and cost reduction remain to be addressed. With regard to individual technical items, there are numerous technical factors that need to be developed by undergoing pilot tests at each oil field while establishing a solid performance. Commercial projects cannot be implemented without preparation. It is necessary to implement feasibility studies before commercialization. Since the total system will involve oil-producing countries, cooperation with these countries is indispensable. Table 3 Technical Tasks Item • CO2 Recovery
• CO2 Liquefaction • CO2 Storage, Shipping • CO2 Ship • CO2 Receiving, Transferring, Injection • CO2 Recycling •
CO2 EOR
Task Enlargement • Minimize Energy Consumption • CO2 Recovery from Dirty Gasses • Alternative of R22 • Effective Utilization of LNG Cold Energy • Enlargementof Liquid CO2 Tank •
General Task • Minimize Energy Consumption • Cost Down • Study the Priority of the Project of Each CO2 Source
• Ditto • Ditto
• Extend the life of Membrane • Optimize C02Recovery Process • Pilot Test for Each Oil Field • IncreaseEOR Efficiency
7, Conclusion As a countermeasure against global warming, EOR using CO2 (CO2 flooding) contributes to the stabilization of CO2 and increases crude oil production. For these reasons, EOR not only effectively produce oil, but also plays a role in the storing of CO2. In the future, it will be most desirable if CO2 can be extracted as industrial resources from reservoirs flooded by CO2. REFERENCES Moritis, G. (1990). CO2 and HC injection lead EOR production increase. In: Oil & Gas Journal, April 23, pp.49-82. APPENDIX Potential cumulative requirement on carbon dioxide for EOR of 63 billion tonnes CO2 all over the world is roughly estimated as a following way. A) Discovered oil in-place is estimated at 4,500 billion barrels. (R.E. Roadifer estimated 4,740 billions in his paper of OGJ, Feb. 24, 1986).
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B) Oil for CO2 flooding is assumed to be lighter than 25 API from O. Moritis report on EOR (OOJ, April 23, 1990). C.D. Masters et al. submitted worldwide and regional distributions of crude oil API gravity to World Petroleum Congress (1987). They estimated that 89% ofoil fell in the range~ C) Van Poolen (1980) pointed out that it is necessary to be deeper than 2,500 ft to attain miscible conditions. From G. Moritis report (1990). 82% of CO2 flooding fell in depth range of 3,00011,000 ft. Depth distribution of oil was shown in M.T. Halbouty's AAPG Memoir 40 (1986). This is for giant or super giant fields, but there is no other data. It showed that 90% of fields fell in the range. D) NPC report (1984) said that CO2 share was 30% of EOR in the U.S. From above mentioned screenings of B and C, it is estimated that 54% of oil in the U.S. become to be candidates for CO2 flooding. An adoption factor is introduced to reflect company's preference for CO2 flooding. In the U.S., the factor is estimated at 56% (=30/54). The factor of 56% is assumed to be applied everywhere. E) An increases in oil recovery by EOR is estimated at 10% ofoil in-place. F) Target of CO2 flooding is obtained as follows: 4,500 billions x 0.89 × 0.90 x 0.56 x 0.1 = 200 billions oil G) An average amount of CO2 from outside into oil fields is estimated at 6 MSCF/STB from W.R. Brock et al. (SPE 18977, 1990). H) The weight of 1MSCF CO2 is equivalent to 52.6kg. I ) Potential cumulative requirement on CO2 for EOR is estimated as follows: 200 billion oil x 6 x 52.6 / 1000 = 63 billion tonnes
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