Scholarly article on topic 'Methodology of CO2 aquifer storage capacity assessment in Japan and overview of the project'

Methodology of CO2 aquifer storage capacity assessment in Japan and overview of the project Academic research paper on "Earth and related environmental sciences"

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Abstract of research paper on Earth and related environmental sciences, author of scientific article — Shigetaka Nakanishi, Yasunobu Mizuno, Tadahiko Okumura, Hideaki Miida, Takumi Shidahara, et al.

Abstract A systematic Japanese nationwide saline-aquifer CO2 storage capacity assessment has been carried out. The project was subdivided into two parts (Missions 1 and 2). We first classified the candidate saline aquifers based on the type of geological structure and the abundance of available data. A total of 146 billion tons of CO2 storage capacity was estimated for the entire country based on oil and gas exploration data using the volumetric method in Mission 1. The potential areas considered in the Mission 1 program are mostly offshore and located far from large scale CO2 emission sources. Mission 2 involved storage capacity estimation for regions near large scale CO2 sources, and the Mission 2 study areas were excluded from the Mission 1 capacity assessments. A total of 27 areas that involve nearby CO2 sources were chosen for the study. A preliminary assessment was performed based on national-scale geological information, and promising sedimentary regions were selected for more detailed examination. Detailed studies were performed for 14 promising areas based on available existing geological data, and regional-scale storage capacities were estimated. A wide range of estimated storage capacities for the various areas emerged, from 10 million tons of CO2 for the Hakodate Bay area to 4.2 billion tons of CO2 for the Osaka Bay area, although the quantitative significance of these assessments must be considered to be only preliminary.

Academic research paper on topic "Methodology of CO2 aquifer storage capacity assessment in Japan and overview of the project"

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Energy Procedia 1 (2009) 2(539-2646

www.elsevier.com/locate/procedia

GHGT-9

Methodology of CO2 aquifer storage capacity assessment in Japan

and overview of the project

Shigetaka Nakanishia*, Yasunobu Mizunob, Tadahiko Okumurac, Hideaki Miidac, Takumi Shidaharad, Shin-ichi Hiramatsue

aElectric Power Development Company (J-Power), Tokyo, Japan bKansai Electric Power Co., Osaka, Japan (former Research Institute of Innovative Technology for the Earth (RITE), Japan) cEngineering Advancement Association of Japan (ENAA), Tokyo, Japan dNEWJEC, Tokyo, Japan (former Central Research Institute of Electric Power Industry (CRIEPI), Japan) eOyo Corporation, Saitama-shi, Saitama, Japan

Abstract

A systematic Japanese nationwide saline-aquifer CO2 storage capacity assessment has been carried out. The project was subdivided into two parts (Missions 1 and 2). We first classified the candidate saline aquifers based on the type of geological structure and the abundance of available data. A total of 146 billion tons of CO2 storage capacity was estimated for the entire country based on oil and gas exploration data using the volumetric method in Mission 1. The potential areas considered in the Mission 1 program are mostly offshore and located far from large scale CO2 emission sources. Mission 2 involved storage capacity estimation for regions near large scale CO2 sources, and the Mission 2 study areas were excluded from the Mission 1 capacity assessments. A total of 27 areas that involve nearby CO2 sources were chosen for the study. A preliminary assessment was performed based on national-scale geological information, and promising sedimentary regions were selected for more detailed examination. Detailed studies were performed for 14 promising areas based on available existing geological data, and regional-scale storage capacities were estimated. A wide range of estimated storage capacities for the various areas emerged, from 10 million tons of CO2 for the Hakodate Bay area to 4.2 billion tons of CO2 for the Osaka Bay area, although the quantitative significance of these assessments must be considered to be only preliminary. © 2009 Elsevier Ltd. All rights reserved.

Keywords: storage capacity; saline aquifer; regional assessment; methodology; countrywide; Japan

1. Introduction

A nationwide CO2 storage capacity assessment of deep saline aquifers in Japan was performed by Tanaka et al. [1] in 1993. The assessment was performed based on available oil and gas exploration data. Storage capacity was estimated by assuming that all of the injected CO2 would be dissolved in the in-situ aqueous phase. It was also

* Corresponding author. Tel.: +81-3-3546-9417; fax: +81-3-3546-9482. E-mail address: shigetaka_nakanishi@jpower.co.jp.

doi:10.1016/j.egypro.2009.02.031

recognized that the high-potential areas considered in the assessment were almost always offshore and distant from existing large scale CO2 emission sources. This source/sink mismatch creates an economic barrier to practical CO2 storage.

The Research Institute of Innovative Technology for the Earth (RITE) and the Engineering Advancement Association of Japan (ENAA) jointly initiated a new nationwide storage capacity assessment project for Japan in 2005, funded by the Ministry of Economy, Trade and Industry (METI). In this project, we revised the methodology for estimating storage capacity based on experience with several CO2 storage projects like the Nagaoka project in Japan.

The project can be divided to two parts - Missions 1 and 2. Mission 1 is a re-evaluation of the storage capacity assessments that were performed previously. We first classified the candidate saline aquifers into categories for storage capacity assessment based on the type of geological structure present and the amount of data available. Then, CO2 storage capacities were estimated using a revised calculation methodology based on the original data set together with newer data acquired between 1993 and 2005. The Mission 1 assessment was performed based on data from oil and gas exploration wells and seismic surveys, and therefore the areas considered are mostly offshore and far away from large scale CO2 emission sources.

Mission 2, on the other hand, involves storage capacity estimation for areas near large scale CO2 emission sources, and therefore these study areas were excluded from the Mission 1 capacity assessment. Several promising sedimentary areas were chosen for detailed study by a preliminary assessment based on a nationwide-scale examination of geological information. Then, geological structures suitable for CO2 storage were identified and characterized based on available existing geological data for each of the selected areas, and regional scale storage capacity was calculated using the same method as in the Mission 1. In the Mission 2 program, beyond just estimating capacity itself, we examined uncertainties in the estimated storage capacities by comparative evaluation of the storage capacities among the regions considered, numerical simulation studies for the inferred geological structure at the various specific areas, and development of a Monte Carlo simulation tool to take into account the effects of uncertainties in the various key parameter values. Guidelines for surveying and estimating storage capacity were also developed in the program.

This paper describes the methodology applied in the assessment and provides an overview of the whole project, focusing particularly on the Mission 2 program mentioned above. The data base system that was developed to provide background information for storage capacity estimation is also discussed.

2. CO2 storage capacity calculations

We used the following expression to calculate the CO2 storage capacity of a deep saline aquifer:

CO2 storage capacity = Sf x A x h x^x Sg xp / BgCO2 (1)

where A, h and ^are aquifer area, effective aquifer thickness and porosity respectively, so that (A x h x ifi) represents the total pore volume within the aquifer volume under consideration. Sg is the supercritical CO2 gas-phase volume fraction in the injected CO2 plume, which we assumed to be 0.50 for purposes of the assessment. p is CO2 density at standard conditions (= 1.976 kg/m3), and BgCO2 is the CO2 volume factor which depends on local pressure and aquifer temperature, so p / BgCO2 represents the in-situ density of pure CO2 at the local pressure and temperature. We introduced a parameter Sf ("storage factor"), the ratio of immiscible CO2 plume volume to total pore volume, which incorporates the combined effects of trap heterogeneity, CO2 buoyancy and displacement efficiency etc. In the calculation, we consider the entire aquifer below a depth of 800 meters where CO2 can be maintained at supercritical conditions, and no distinction is made between CO2 stored by the various mechanisms. It is assumed that injected CO2 may be trapped for extended periods of time by a combination of trapping mechanisms.

The parameter Sf is coincidentally similar to Cc: the "capacity coefficient" introduced in CSLF (Carbon Sequestration Leadership Forum) 2007 [2] (also, see Bachu et al. [3]) and also to E: the "storage efficiency factor" used in USDOE 2007 [4]. Although it is difficult to estimate an appropriate value of Sf for the nationwide assessment, we assumed Sf = 0.50 for "Category A" anticline structures (see discussion below) because such structures have limited areal extent so that CO2 buoyancy effects will predominate, and we assumed Sf = 0.25 for Category B, in consideration of probable heterogeneity effects in aquifer systems with relatively large areal extent. We clearly recognize that the appropriate values of the various parameters in Equation (1) are poorly established and

are likely to be site-specific, especially the storage factor. We decided, therefore, that the parameter values that were used in our calculations for each area would be clearly documented within the data base, so that improved estimates may be made in the future as new insights and field information emerge.

3. Re-evaluation of the previous assessment

Mission 1 of the project re-evaluated the results of the previous storage capacity assessment by Tanaka et al. [1] in 1993; the Mission 1 results are discussed in detail by Takahashi et al. [5], and briefly summarized below. We first subdivided the various areas to be considered into two broad groups (Categories A and B) based on geological structure. Category A represents a closed anticline system, suitable for structural CO2 trapping. Category A was subdivided into three sub-categories according to the quantity of the data available. Category A1 includes fully-developed and well-understood oil and gas fields with abundant subsurface geological data. Category A2 includes areas where results from exploratory drilling and seismic surveys are both available. Category A3 includes areas where only seismic survey data are available. Category B represents CO2 storage in the other geological structures, and was subdivided into two groups. Category B1 includes three dissolved-in-water type natural gas fields for which substantial subsurface measurements are available. Category B2 includes 16 large offshore areas from 1,000 km2 to 50,000 km2 in size with field information largely restricted to seismic surveys.

Table 1 summarizes the results of the re-evaluation based on the both the original data set and more recent data, using the revised methodology. A total of 146 Gt-CO2 of storage capacity (30 Gt-CO2 in Category A and 116 Gt-CO2 in Category B) was estimated. Figure 1 shows the locations for which storage capacities were appraised, as well as other pertinent information. Because the Mission 1 assessment was performed based on data from oil and gas exploration wells and seismic surveys, the areas considered are mainly offshore, at considerable distances from the coastline and from existing large-scale CO2 emission sources, which are generally located along the coast.

Table 1 Results of Mission 1 CO2 storage capacity assessment.

G eologjcaldata

C ategory A

Sjtorageh an antrIhalstructure)

C ategory B

(Storage ]h a geobgial structure with a stratfcpaphjc trapphg, etc.)

Existiig oí]/gas field

Exploiatry well and seism ic survey

Well and seism ic exploration

data is abundant.

3.5Gt-C0,

W ell and seism ic exploration

data is available.

A 2 5.2Gt-C0;

27.5Gt-C0,

Basic seisin ic exploration

Seism ic exploration data is available, but no w ell data.

A 3 21.4Gt-C0,

8 8.5G t-C 0,

C oncept of storage

Sub total

30. lGt-C0,

116.OGt-C0,

146.1Gt-C0;

N0 TE) ]hbnd basils, such as Seto iibnd sea, 0 saka Bay aie exclided. ^onfy thosebcated h offshore shalbwerthan 200m.

AfterRITE/ENAA (2006), Report on D evebpm ent of C albon Dioxide GeobgfcalStoiage th Japanese)

Northern _ Kyushu Area

Tokyo Bay Area Ise Bay Area

geophysical prospecting line A-2

(except

depth/lithofacies) Boundary of sea area

(natural gas field)

f. ;• (more than 800 m in thickness)

shallower than 200 m in depth

shallower than 1000 m in depth

100 2« M0

Figure 1 Locations of aquifers and geophysical prospecting lines.

4. Storage Capacity estimation of the regions near CO2 emission sources

4.1 Area selection and preliminary assessment

The aim of the Mission 2 program is to examine the possibility of CO2 aquifer storage in locations near CO2 emission sources, to minimize the cost of CO2 transport in the overall carbon-capture-and-storage chain. We first examined promising areas near CO2 emission sources as shown in Figure 2. These include four areas near large CO2 emission sources (Tokyo Bay, Ise Bay, the Osaka Bay area and northern Kyushu), and 23 other candidate areas near CO2 emission sources. A preliminary assessment of the possibility of CO2 storage in the latter 23 areas was performed based on nationwide-scale geological information. The result of this preliminary 23-area assessment is summarized in Table 2. In the table, the A and O symbols indicate that a suitable aquifer formation may be present at depth in the area. Candidate "aquifer" and "cap rock" formations in the area are also summarized in the table. The x symbol indicates that CO2 cannot be stored in the area for one reason or another. For example, Pre-Tertiary

basement rocks are present at shallow depths in the Seto Inland Sea, so that CO2 cannot be maintained in a supercritical condition in the aquifer in that area.

Legend

nildfe s

^^ Assessment are en issnn sources

NOTE: Seto Inland Sea is categorised in hrgescale en issrin sources essentially.

Assessn ent area near large scale em issiin soureces, that hed been assesed ii FY 2005.

©Uchiira ©Hakodate Bay

O Therm alpower station O Iron m anufecturing plant O C em ent plant

numbers indicate am ount of ^£,088 cq2 emission every prefecture

.[©Sendai Bay t-C02/year

nawa Island

Figure 2 Storage capacity assessment for areas near large and intermediate scale emission sources (M-2).

Table 2 Preliminary evaluation of 23 areas near CO2 emission sources.

Site name Target stratum Characteristic Judge Site name Target stratum Characteristic Judge

©Uchiura Bay Upper Kuromatsunai (siltstone) Lower Kuromatsunai (sandstone/tuff) Confined sediments distribution absence of offshore data A ©Offshore of Wakayama Tanabe group (ss/ms ), Sea sediments Equivalent of Osaka group Tanabe group is far from CO2 source Small basin under the sea A

©Hakodate Bay Tate formation (mudstone ) Assa member (coarse tuff) Kikonai formationsandstone) Confined sediments distribution Absence of offshore data A ©Offshore of Harima Tonosho group Kobe group Osaka group Thin lithofacies X

©Offshore of Hachinohe Kamanosawa formation i|mudstone/sandstone ) Marked change in lithofacies Unkown lithofacies A ©Seto Inland Sea Akitsu /Fukuyama fomation/ Maesima formation (Paleocene Thin lithofacies X

©Offshore of Noshiro Tentokuji formation fms/ss ) Funakawa formation Onnagawa formation Fold zone Thick Neogene stratum o ©Offshore of Suo Hatabu formation (Neogene ) Ube Group, etc. (Paleogene ) Thin Neogene Possibility existing Paleogene -

©Offshore of Akita Lower Tentokuji formation Katsurane phase (siltstone (ss predominant layers ) Fold zone Thick Neogene stratum o ©Offshore of Misumi Josoji formation (ns) Kour formation (ss/ms ) Volcanic rock dominant (onshore) Under the sea A

©Offshore of Sakata Tentokuji formation fms/ss ) Funakawa formation (tuff/ms ) Onagawa formation (ms/ss ) Fold zone Thick Neogene stratum o ©Tachibana Bay Stratum of Continental sherf/continental sloop from Neogene to Plistocene Shallow depth X

©Sendai Bay Otsuka formation (siltstone Below Matsushima formation Sandstone ) Half graben Confined sediments distribution o ©Beppu Bay Equivalent of Sekinan formation ^volcanic sediments/sand/gravel ) Confined rese^oir distribution A lot of active fault A

©Offshore of Soma-Kashima (north) Taga group fmudstone ) Takaku group/sirado group/ yunagaya group (sandstone) Homoclinic structure Broad distribution , Thick layer o ©Offsore of Matsushima Sakitoformation Matsushima, etc Nakato ,Terashima, Akasaki formetion, etc. Sediments of Paleogene Coal field A

©Offshore of Kashima same same o q Offshore of Amakusa Equivalent of Kuchinotsu group (mud ,sand ) Sediment filling graben Lack of data A

©Toyama Bay (onshore ) Higashi bessyo formation (siltstone predominant layers Kurosetani formation ^s ) Marked change in lithofacies Deep depth of the sea o 0 Offshore of Sendai Neogene sediments in the broad continental shelf Possibility distributing under the sea Unknown lithofacies -

©Wakasa Bay Hokutan group (volcanic rock/ss ) Uchiura grou (same ) Volcanic rocks dominant Out of adequate depth X Okinawa 0 Island Yonabaru formation (ms ) Tomigusuku formation (ss Alternation of sandstone and mudstone Lack of date in the sea O

©Offshore of Kumano Stratum of continental slope from Neogene to Pleistocene (unknown lithofacies ) Increasing depth rapidly X Jud iikely ,A possible ,x impossible , - unknown Yellow storage capacity was estimated so far.

4.2 Storage capacity estimation of selected area

After the preliminary assessment, fourteen study areas were selected for more detailed investigation based on available existing geological data. The fourteen areas include four areas near particularly large CO2 sources (the Tokyo Bay area, the Ise Bay area, the Osaka Bay area and northern Kyushu), and ten other areas (Uchiura Bay area, Hakodate Bay area, offshore near Akita, Sendai Bay area, offshore near Soma-Kashima, Toyama Bay area, Beppu Bay area, offshore near Matsushima, offshore near Amakusa, and Okinawa Island).

In this part of the study, we first collected as much existing geological data as possible, including seismic survey data, gravity data, deep well data and so on. Then the geological structure suitable for CO2 storage was delineated based on various studies. The idealized geological structure to be quantified is illustrated in Figure 3. The caprock/aquifer geometry below 800 meters depth was estimated for each study area, and a regional-scale storage capacity was calculated using the same volumetric method. The analysis of the Osaka bay area is discussed in detail by Hashimoto et al. [6], and is a representative example. The geometric parameters (aquifer area, effective thickness and porosity) for the storage capacity calculation were assigned based on the best geological information available, and the CO2 volume factor was determined using the average temperature and depth (i.e. pressure) within the aquifer. A storage factor of 0.25 was tentatively adopted. Figure 4 shows the areal extent of the Osaka Bay aquifer.

The same kind of analysis was performed for each of the fourteen areas studied, which resulted in a wide range of estimated storage capacities (from 10 million tons of CO2 for the Hakodate Bay area to 4.2 billion tons of CO2 for the Osaka Bay area). Table 3 lists representative results of the Mission 2 assessment. These results must be regarded as preliminary, since available data sets are insufficient to provide good quantitative estimates of all of the unknown parameter values.

5. Comparative evaluation among areas considered near CO2 sources

The quality and quantity of the existing data set available for purposes of the study varied substantially from one study area to the next, so the quantitative reliability of the capacity estimates presumably varies in a similar fashion from site to site. To evaluate differences of the accuracy of storage capacity calculated for each area, Ogawa et al. [7] examined the data quality and quantity for the different areas. Then they tried to perform a comparative evaluation of the estimated CO2 capacities among these regions.

6. Numerical simulation study

The geological structure of the potential storage areas near CO2 sources is not necessarily anticlinal, but will often be monoclinal. A numerical simulation study of CO2 migration in a monocline structure was performed to obtain insights concerning lateral migration distance after CO2 injection ceases and how it influences storage capacity estimates. CO2 migration distances should be considered in the definition of effective aquifer volume, especially in identifying lateral boundaries. Kawata et al. [8] describe such a sensitivity study performed for the Ise Bay area. Their simulation study helped identify parameters to which CO2 migration distances are sensitive.

7. Data base system

A data base system was developed to aid in storage capacity estimation. The system provides background information about the storage capacity assessment, so that one can trace the path of the storage capacity estimation process and gain insights into the uncertainties involved. The data base system incorporates the compiled map of GIS data from the Mission 1 program, geological data and definition of parameters for storage capacity estimation from the Mission 2 program, basin data catalogs for each basin and the relevant literature list. Figure 5 shows some images from the data base system.

• Distribution of Tertiary - Quaternary sedimentary rocks

• Geological structure with cap rock and aquifer

Geological conditions of the reservoir for CO2 storage

{■ deeper than 800m depth

■ shallower than 200m of water depth

■ fault, etc.

~ T ■

Depth:

800m or more

Cap rock

(mudstone predominant layer)

Aquifer

(sandstone predominant layer)

Figure 3 Conceptual reservoir model for CO2 storage in the Mission 2 assessment.

Table 3 Representative results of Mission 2 CO2 storage capacity assessments.

S ie nam e Sie bcation Detail class ifcatim A;Area t»!> h; Effective thickness 60 4>; Porosity A verage temperature in the reservoir eco A verage depth of the re servo ir 60 BgC02 Volum e iactor Sf; Storage iactor io; CO 2densiy Estin ated storage capacity Ot-co2) Rem arks

H akodate B ay ofEshore 37 30 0.12 70 1500 0.00397 0.25 0.001976 0.01

0 saka B ay ofEshore 400 600 0.25 60 1400 0.00353 0.25 0.001976 4.20

0 fEshore of M atsushm a ofEshore Sakito-M atsushm a coalfeB 373 532 0.08 90 2000 0.00371 0.25 0.001976 1.06

Takashm a coalfeB 24 462 0.08 80 1800 0.00376 0.06

0 khaw a Isknd ofEshore Tom igusuku fern at:bn 143 98 0.39 45 1200 0.00307 0.25 0.001976 0.44 ConcBerhgTl sub group

The area where >Ma-1 layer are distributed at -800m ASL : about 400km2

Figure 4 Geological map of Osaka Bay (one of the areas near large scale emission sources).

National scale sites map

Regional scale geologic map graphic map and geologic column of a site

fWB w ¿H*iim№i8H a« fMiau ■

I J I_=_I

Figure 5 Representative unfolded image of the database system for a sedimentary basin near a CO2 emission source (Hakodate Bay area).

8. Conclusions

A systematic nationwide storage capacity assessment for saline aquifers in Japan was performed. The results may be summarized as follows:

• A total of 146 billion tons of CO2 storage capacity was estimated based on available oil and gas exploration data.

• Moreover, the CO2 storage capacities of 14 specific sites located near CO2 emission sources were estimated, based on available data. These 14 study areas are not included in the above 146 Gt-CO2 capacity assessment.

• These are regional-scale assessments, and due to inadequacy of the existing data, the probable accuracy of the estimated storage capacities is fairly low. In another words, these storage estimates represent "resources", not "reserves", in the sense that these terms are used in the energy and mining industries.

• These storage capacity estimates should be refined by additional study and acquisition of new data.

• Further work is needed to improve the estimate of average "storage factor".

References

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2. CSLF (Carbon Sequistration Leadership Forum): Estimation of CO2 storage capacity in geological media-Phase II-, CSLF-T-2007-04, 2007.

3. S. Bachu, D. Bonijoly, J. Bradshaw, R. Burrruss, S. Holloway, N.P. Christensen and O.M. Mathiassen. CO2 storage capacity estimation:

Methodology and gaps. International Journal of Greenhouse Gas Control. V.1, no.4, 2007, 430.

4. USDOE (U.S. Department of Energy, Office of Fossil Energy), Carbon Sequestration Atlas of United States and Canada, 2007, 86

5. T. Takahashi, T. Ohsumi, K. Nakayama, K. Koide and H. Miida. Estimation of CO2 aquifer storage potential in Japan, Proceedings of GHGT-9.

6. T. Hashimoto, S. Hiramatsu, T. Yamamoto, H. Takano, M. Mizuno and H. Miida, Evaluation of CO2 aquifer storage capacity in the vicinity of

a large emission area in Japan: Case history of Osaka Bay, Proceedings of GHGT-9, 2008.

7. T. Ogawa, T. Shidahara, S. Nakanishi, T. Yamamoto, K. Yoneyama, T. Okumura and T. Hashimoto. Storage capacity assessment in Japan:

Comparative evaluation of CO2 aquifer storage capacities across regions. Proceedings of GHGT-9, 2008.

8. Y. Kawata, H. Ohkuma, S. Yokoi, S. Nakanishi, K. Yoneyama and T. Hashimoto. Sensitivity analysis of CO2 migration in deep saline aquifer

of Ise Bay, Japan, using heterogeneous and homogeneous 2D models based on depositional facies analysis, Proceedings of GHGT-9, 2008.