Geochemistry of formation waters from oil and gas fields in Akita and Yamagata Prefectures, northeastern Japan.

進, 加藤; 善雄, 安田; 英毅, 西田

doi:10.3720/japt.65.229

Cited by 10 publications

(4 citation statements)

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“…(b) A profile of the groundwater salinities showing that the saline zone becomes shallower toward the hilly area (Yoshimura et al, 2004). (c): Distribution of mud volcanoes (Shinya & Tanaka, 2005), NaCl-rich hot spring (Watanabe, Oki, Sato, & Kusakabe, 1996), NaCl-rich groundwater in landslide (Tiwari & Ajmera, 2015;Watanabe et al, 2009), deep well (Japan National Oil Corporation, 1991, 1996, and CSAMT survey areas (Sato, 2014;Sato et al, 2017;Suzuki, Tokuyasu, & Tanaka, 2009) data for the oil fields of Yamagata and Akita (Figure 14) (Kato, 1990;Kato et al, 2000;Kato & Kajiwara, 1986;Sasaki, 1962). These vertical distributions of salinity are based on the water chemistry data obtained for each formation from a large number of deep wells in both oil fields and show the tendency of the salinity depth distribution in each oil field.…”

Section: Discussionmentioning

confidence: 99%

“…The formation names are from the Niigata area F I G U R E 1 4 Schematic diagram showing the vertical distribution of the groundwater Cl − concentration in the oil fields, eastern marginal region of the Japan Sea. We collected data on the Cl − distribution in Niigata (Kato & Kajiwara, 1986), Yamagata (Kato, Yasuda, & Nishida, 2000;Sasaki, 1962), and Akita (Kato, 1990;Kato et al, 2000) water from the data on the groundwater chemistry and deep well logging.…”

Section: Discussionmentioning

confidence: 99%

“…Among the Neogene distribution areas, the eastern marginal region of the Japan Sea has the highest density of landslides (Doshida, 2015), and as described thus far, one of the causes of landslides in Higashi‐Kubiki is presumed to be groundwater with high salinity. Other areas of Neogene rocks in the eastern marginal region of the Japan Sea are also inferred to have saline water at depth from data for the oil fields of Yamagata and Akita (Figure 14) (Kato, 1990; Kato et al, 2000; Kato & Kajiwara, 1986; Sasaki, 1962). These vertical distributions of salinity are based on the water chemistry data obtained for each formation from a large number of deep wells in both oil fields and show the tendency of the salinity depth distribution in each oil field.…”

Section: Discussionmentioning

confidence: 99%

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Distribution of fossil seawater and its role in Neogene sedimentary rock landslides in Niigata, eastern marginal region of the Japan Sea

et al. 2020

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The Neogene marine sedimentary rock area in the eastern marginal region of the Japan Sea is an area with some of the highest landslide densities in Japan. Some of the landslides in this area have been known to involve saline groundwater, which can be the cause of these landslides. In order to demonstrate the relationships between landslides and saline water, topographic, geological, groundwater, and electromagnetic surveys were performed in the eastern marginal region of the Japan Sea. Many landslides and gravitational slope deformations with linear depressions and small scarps were recognized in the study area. The resistivity profile obtained by an electromagnetic survey suggests that there is a wide zonal distribution of saline water with salt concentrations equivalent to seawater at depths of 50-100 m or more and that the groundwater shallower than 50 m has an electrical conductivity of less than 100 mS/m. The shallow resistive groundwater is inferred to be meteoric water that replaced the saline groundwater, which likely weakened the bedrock, resulting in landslides. A ridge of competent tuff overlying mudstone has many linear depressions from gravitational slope deformation and low-resistivity water to a depth of 600 m, which suggests that the mudstone was weakened by water replacement and deformed under the tuff caprock. The saline groundwater is inferred to be fossil seawater trapped in pores during sediment deposition, which is brought near the ground surface along with rocks by tectonic movement in the hills. Thus, the saline water and its fresh water replacement are among the important basic causes of the landslides. The oil well data obtained in the eastern marginal region of the Japan Sea suggest that such saline water replacement has occurred widely and that replacement is likely one of the predispositions for the frequent landslides there. K E Y W O R D S eastern marginal region of the Japan Sea, fossil seawater, landslide, Neogene sedimentary rock 1 | INTRODUCTION Landslides occur in various ways depending on geology and environment (Hungr, Leroueil, & Picarelli, 2014; Varnes, 1978). Rock weathering is one of the major causes of landslides because it produces a considerable decay of the physical-mechanical properties of the original rock, predisposing the slope to instability processes

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Distribution of fossil seawater and its role in Neogene sedimentary rock landslides in Niigata, eastern marginal region of the Japan Sea

et al. 2020

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“…Although the δ 18 O of the KDE is close to 0, δD is much lower than in current seawater. Fossil seawater and oilfield brine often has a lighter hydrogen isotope ratio than current seawater (Kato and Kajiwara 1986;Kato et al 2000;Muramatsu et al 2012). However, the δD of fossil seawater and oilfield brine is approximately − 20‰ at minimum, and an isotope ratio shift up to − 50‰ has not been reported yet.…”

Section: (A) Meteoric Watermentioning

confidence: 99%

Original composition and formation process of slab-derived deep brine from Kashio mineral spring in central Japan

Kusuhara

Kazahaya

Morikawa

et al. 2020

Earth Planets Space

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Brine samples from the wells in the Kashio mineral spring (an “Arima-type” hot spring at Ooshika-Mura, central Japan) were analyzed to determine the original chemical and isotopic compositions of the deep brine end-member before its dilution by meteoric water and to elucidate the origin of the end-member. The trends of variation between Cl, δD, and δ18O indicated the existence of a two-component mixing system and a systematic variation in the mixing ratio, which were mentioned in previous studies. By carefully tracking the variation in tritium (3H) and atmospheric noble gas in the brine, the Cl concentration in the end-member was determined to be 24,000 mg/L. This value is consistent with the result of previous studies. Based on the estimated composition and other related data, we inferred that the end-member originated from slab-derived fluid, which in turn may have undergone oxygen isotope exchange reactions with minerals. Although both the Arima and Kashio brines are considered to be derived from fluid dehydrated from the Philippine Sea slab, the chemical and isotopic compositions of the Kashio end-member are different from those of the Arima end-member. In particular, the Kashio end-member is characterized by low Cl concentration (~ 40% lower than that in the Arima end-member), low hydrogen isotope ratio, and low 3He/4He ratio (1.4 Ra). These results indicate that the chemical and isotopic compositions of the slab-derived fluid are different for each location. The significant difference in δD could reflect the difference in the dehydration depth. Finally, the low temperature and relatively low 3He/4He ratio of the brine end-member could be explained by its long residence time within the crust.

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Lithium isotope systematics of methane-seep carbonates as an archive of fluid origins and flow rates

Miyajima,

Araoka,

Yoshimura

et al. 2023

Geochimica et Cosmochimica Acta

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Geochemistry of formation waters from oil and gas fields in Akita and Yamagata Prefectures, northeastern Japan.

Cited by 10 publications

References 9 publications

Distribution of fossil seawater and its role in Neogene sedimentary rock landslides in Niigata, eastern marginal region of the Japan Sea

Distribution of fossil seawater and its role in Neogene sedimentary rock landslides in Niigata, eastern marginal region of the Japan Sea

Original composition and formation process of slab-derived deep brine from Kashio mineral spring in central Japan

Lithium isotope systematics of methane-seep carbonates as an archive of fluid origins and flow rates

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