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Article: Salinity variation of formation water and diagenesis reaction in abnormal pressure environments

TitleSalinity variation of formation water and diagenesis reaction in abnormal pressure environments
Authors
KeywordsAbnormally Pressured System
Diagenesis Reaction
Formation Water
Shiwu Depression
Yinggehai Basin
Issue Date2003
Publisher中國科學院. The Journal's web site is located at http://jdxg.chinajournal.net.cn/
Citation
Science In China, Series D: Earth Sciences, 2003, v. 46 n. 3, p. 269-284 How to Cite?
AbstractAn understanding to the chemistry of formation waters in sedimentary basins is important for many geological processes, such as the fluid-rock interaction, the migrating paths of fluid and the entrapment mechanisms of hydrocarbon. This paper deals with the salinity variation of formation water and diagenesis reaction in the abnormally pressured system. The Shiwu depression of the Songliao basin and the Yinggehai basin are selected for case studies. The studies indicate that there is a distinct difference in the chemistry of subsurface water between hydropressured and abnormally pressured systems. The Shiwu depression of the Songliao basin is composed of terrigeneous clastics in fluvial-lacustrine environments, which contain brackish water with salinity ranging from less than 1000 mg/L to 12000 mg/L. Water composition varies with depth and hydrochemical regions. In the underpressured strata deposited during the rifting periond, the formation water is characterized by CaCl2 type water with high salinity. NaHCO3-dominanted water with lower salinity occurs at the hydropressured strata deposited during the post-rifting period. In this halite-free basin, brackish water may be attributed to the condensation of meteoric water and water-rock interaction. In the deeply buried underpressured water, a predominated diagenesis reaction resulting in enrichment of Ca and Cl and reduction of Na may be related to the albitization of plagioclase following the basinal fluid line (BFL). The Yinggehai basin constitutes clastic deposits in nearshore, neritic, shelf environments and contains brackish and saline water with salinity ranging from less than 15000 mg/L to 50000 mg/L. Pore water in these marine deposits must have originated from seawater. In the overpressured system, however, the formation water has much lower salinity and ion concentrations (except bicarbonate and carbonate) than normal seawater. The low salinity indicates that interstitial connate seawater is diluted by the water released from the transformation of smectite to illite. High bicarbonate and carbonate concentrations may contribute to mineral dehydration and kerogen-cracking reactions. Furthermore, low salinity water also occurs near and above the top of the geopressured zone in the diapiric structures, which may indicate that pore water with normal seawater salinity has been mixed by fresher saline water from deeper portions of the overpressured stratigraphic section. This study indicates that there are different hydrochemical environments and distinct diagenesis reactions within the abnormally pressured systems. Variation of salinity in different pressured systems may provide information of fluid flow and hydrocarbon accumulation. Recent exploration has confirmed that the area near or above the top of abnormally pressured compartment was a fluid release zone, and also an available hydrocarbon accumulation zone, where plenty of commercial hydrocarbon has been discovered.
Persistent Identifierhttp://hdl.handle.net/10722/151104
ISSN
2011 Impact Factor: 1.588
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorXie, Xen_US
dc.contributor.authorJiao, JJen_US
dc.contributor.authorLi, Sen_US
dc.contributor.authorCheng, Jen_US
dc.date.accessioned2012-06-26T06:17:07Z-
dc.date.available2012-06-26T06:17:07Z-
dc.date.issued2003en_US
dc.identifier.citationScience In China, Series D: Earth Sciences, 2003, v. 46 n. 3, p. 269-284en_US
dc.identifier.issn1006-9313en_US
dc.identifier.urihttp://hdl.handle.net/10722/151104-
dc.description.abstractAn understanding to the chemistry of formation waters in sedimentary basins is important for many geological processes, such as the fluid-rock interaction, the migrating paths of fluid and the entrapment mechanisms of hydrocarbon. This paper deals with the salinity variation of formation water and diagenesis reaction in the abnormally pressured system. The Shiwu depression of the Songliao basin and the Yinggehai basin are selected for case studies. The studies indicate that there is a distinct difference in the chemistry of subsurface water between hydropressured and abnormally pressured systems. The Shiwu depression of the Songliao basin is composed of terrigeneous clastics in fluvial-lacustrine environments, which contain brackish water with salinity ranging from less than 1000 mg/L to 12000 mg/L. Water composition varies with depth and hydrochemical regions. In the underpressured strata deposited during the rifting periond, the formation water is characterized by CaCl2 type water with high salinity. NaHCO3-dominanted water with lower salinity occurs at the hydropressured strata deposited during the post-rifting period. In this halite-free basin, brackish water may be attributed to the condensation of meteoric water and water-rock interaction. In the deeply buried underpressured water, a predominated diagenesis reaction resulting in enrichment of Ca and Cl and reduction of Na may be related to the albitization of plagioclase following the basinal fluid line (BFL). The Yinggehai basin constitutes clastic deposits in nearshore, neritic, shelf environments and contains brackish and saline water with salinity ranging from less than 15000 mg/L to 50000 mg/L. Pore water in these marine deposits must have originated from seawater. In the overpressured system, however, the formation water has much lower salinity and ion concentrations (except bicarbonate and carbonate) than normal seawater. The low salinity indicates that interstitial connate seawater is diluted by the water released from the transformation of smectite to illite. High bicarbonate and carbonate concentrations may contribute to mineral dehydration and kerogen-cracking reactions. Furthermore, low salinity water also occurs near and above the top of the geopressured zone in the diapiric structures, which may indicate that pore water with normal seawater salinity has been mixed by fresher saline water from deeper portions of the overpressured stratigraphic section. This study indicates that there are different hydrochemical environments and distinct diagenesis reactions within the abnormally pressured systems. Variation of salinity in different pressured systems may provide information of fluid flow and hydrocarbon accumulation. Recent exploration has confirmed that the area near or above the top of abnormally pressured compartment was a fluid release zone, and also an available hydrocarbon accumulation zone, where plenty of commercial hydrocarbon has been discovered.en_US
dc.languageengen_US
dc.publisher中國科學院. The Journal's web site is located at http://jdxg.chinajournal.net.cn/zh_HK
dc.relation.ispartofScience in China, Series D: Earth Sciencesen_US
dc.subjectAbnormally Pressured Systemen_US
dc.subjectDiagenesis Reactionen_US
dc.subjectFormation Wateren_US
dc.subjectShiwu Depressionen_US
dc.subjectYinggehai Basinen_US
dc.titleSalinity variation of formation water and diagenesis reaction in abnormal pressure environmentsen_US
dc.typeArticleen_US
dc.identifier.emailJiao, JJ:jjiao@hku.hken_US
dc.identifier.authorityJiao, JJ=rp00712en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1360/03yd9025en_US
dc.identifier.scopuseid_2-s2.0-0041470365en_US
dc.identifier.hkuros81062-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0041470365&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume46en_US
dc.identifier.issue3en_US
dc.identifier.spage269en_US
dc.identifier.epage284en_US
dc.identifier.isiWOS:000181672200008-
dc.publisher.placeChinaen_US
dc.identifier.scopusauthoridXie, X=7402761346en_US
dc.identifier.scopusauthoridJiao, JJ=7102382963en_US
dc.identifier.scopusauthoridLi, S=7409237578en_US
dc.identifier.scopusauthoridCheng, J=7405937829en_US

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