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Shengli Oilfield, China as a natural analogue of CO 2 storage: Diagenetic fluid evolution mode and potentials for carbon sequestration
Author(s) -
Li Fulai,
Li Wenshuai
Publication year - 2017
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.3024
Subject(s) - calcite , ankerite , geology , diagenesis , authigenic , fluid inclusions , meteoric water , siderite , geochemistry , pyrite , chlorite , illite , mineralogy , carbonate , quartz , clay minerals , hydrothermal circulation , chemistry , paleontology , organic chemistry
The Shengli Oilfield is discussed to investigate CO 2 trapping mechanisms involved in geothermal oil reservoir systems. Diagenetic fluid evolution of the dawsonite‐bearing sandstones from the Dongying Sag, Bohai Bay Basin, China, was studied to understand the CO 2 migration and accumulation and the formation of dawsonite, as a possible mechanism for mineral trapping of CO 2 in geothermal fields. Information about the petrology, dawsonite‐forming fluid, authigenic mineral associations, and diagenetic fluid evolution mode was analysed using techniques including thin‐section identification, scanning electron microscope observation, X‐ray diffraction analysis, X‐ray fluorescence spectrum analysis, hydrochemistry, and stable isotope analyses. The paragenetic sequence, from early to late, is early calcite (A)–compaction–dissolution–quartz overgrowth–late calcite (B 1 )–ferrocalcite (A)–dawsonite–late calcite (B 2 )–ferrocalcite (B)–ankerite–siderite or pyrite. The current in situ formation water type of the dawsonite‐bearing sandstone strata is NaHCO 3 , with the typical characteristics of weak alkaline, high mineralization, and high Na + + K + and HCO 3 − content. The formation fluid from which the dawsonite forms is mainly sealed underground brine, which has been affected by atmospheric precipitation and magmatic activity, and is thus mixed with surface meteoric water and subsurface hydrothermal fluid. The fluid evolution process sequence is alkaline fluid environment prior to CO 2 influx, an early micritic or sparry calcite (A) association; acidic fluid environment after CO 2 influx, a quartz overgrowth and kaolinite association; alkalescent fluid environment, an association of late calcite (B 1 ), ferrocalcite (A), and illite; alkaline fluid environment, a dawsonite and late calcite (B 2 ) association; and weak‐alkaline fluid environment, an association of ferrocalcite (B), ankerite, siderite, and pyrite.