TY - JOUR
T1 - Diagenesis and reservoir quality evolution of palaeocene deep-water, marine sandstones, the Shetland-Faroes Basin, British continental shelf
AU - Mansurbeg, H.
AU - Morad, S.
AU - Salem, A.
AU - Marfil, R.
AU - El-ghali, M. A.K.
AU - Nystuen, J. P.
AU - Caja, M. A.
AU - Amorosi, A.
AU - Garcia, D.
AU - La Iglesia, A.
N1 - Funding Information:
This research work has been conducted within the framework of the EUROMARGIN project, which was launched and organized by the European Science Foundation (ESF). Former Saga petroleum is gratefully acknowledged for providing core samples and other useful data.
PY - 2008/6
Y1 - 2008/6
N2 - The Palaeocene, deep-water marine sandstones recovered from six wells in the Shetland-Faroes Basin represent lowstand, transgressive and highstand systems tract turbiditic sediments. Mineralogic, petrographic, and geochemical analyses of these siliciclastics are used to decipher and discuss the diagenetic alterations and subsequent reservoir quality evolution. The Middle-Upper Palaeocene sandstones (subarkoses to arkoses) from the Shetland-Faroes Basin, British continental shelf are submarine turbiditic deposits that are cemented predominantly by carbonates, quartz and clay minerals. Carbonate cements (intergranular and grain replacive calcite, siderite, ferroan dolomite and ankerite) are of eogenetic and mesogenetic origins. The eogenetic alterations have been mediated by marine, meteoric and mixed marine/meteoric porewaters and resulted mainly in the precipitation of calcite (δ18OV-PDB=-10.9‰ and -3.8‰), trace amounts of non-ferroan dolomite, siderite (δ18OV-PDB=-14.4‰ to -0.6‰), as well as smectite and kaolinite in the lowstand systems tract (LST) and highstand systems tract (HST) turbiditic sandstone below the sequence boundary. Minor eogenetic siderite has precipitated between expanded and kaolinitized micas, primarily biotite. The mesogenetic alterations are interpreted to have been mediated by evolved marine porewaters and resulted in the precipitation of calcite (δ18OV-PDB=-12.9‰ to -7.8‰) and Fe-dolomite/ankerite (δ18OV-PDB=-12.1‰ to -6.3‰) at temperatures of 50-140 and 60-140 °C, respectively. Quartz overgrowths and outgrowth, which post- and pre-date the mesogenetic carbonate cements is more common in the LST and TST of distal turbiditic sandstone. Discrete quartz cement, which is closely associated with illite and chlorite, is the final diagenetic phase. The clay minerals include intergranular and grain replacive eogenetic kaolinite, smectite and mesogenetic illite and chlorite. Kaolinite has been subjected to mesogenetic replacement by dickite. The K-feldspar and plagioclase grains have been albitized. Dissolution of calcite cement and of framework grain (feldspar, volcanic fragments and mud intraclasts) has resulted in a considerable enhancement of reservoir quality.
AB - The Palaeocene, deep-water marine sandstones recovered from six wells in the Shetland-Faroes Basin represent lowstand, transgressive and highstand systems tract turbiditic sediments. Mineralogic, petrographic, and geochemical analyses of these siliciclastics are used to decipher and discuss the diagenetic alterations and subsequent reservoir quality evolution. The Middle-Upper Palaeocene sandstones (subarkoses to arkoses) from the Shetland-Faroes Basin, British continental shelf are submarine turbiditic deposits that are cemented predominantly by carbonates, quartz and clay minerals. Carbonate cements (intergranular and grain replacive calcite, siderite, ferroan dolomite and ankerite) are of eogenetic and mesogenetic origins. The eogenetic alterations have been mediated by marine, meteoric and mixed marine/meteoric porewaters and resulted mainly in the precipitation of calcite (δ18OV-PDB=-10.9‰ and -3.8‰), trace amounts of non-ferroan dolomite, siderite (δ18OV-PDB=-14.4‰ to -0.6‰), as well as smectite and kaolinite in the lowstand systems tract (LST) and highstand systems tract (HST) turbiditic sandstone below the sequence boundary. Minor eogenetic siderite has precipitated between expanded and kaolinitized micas, primarily biotite. The mesogenetic alterations are interpreted to have been mediated by evolved marine porewaters and resulted in the precipitation of calcite (δ18OV-PDB=-12.9‰ to -7.8‰) and Fe-dolomite/ankerite (δ18OV-PDB=-12.1‰ to -6.3‰) at temperatures of 50-140 and 60-140 °C, respectively. Quartz overgrowths and outgrowth, which post- and pre-date the mesogenetic carbonate cements is more common in the LST and TST of distal turbiditic sandstone. Discrete quartz cement, which is closely associated with illite and chlorite, is the final diagenetic phase. The clay minerals include intergranular and grain replacive eogenetic kaolinite, smectite and mesogenetic illite and chlorite. Kaolinite has been subjected to mesogenetic replacement by dickite. The K-feldspar and plagioclase grains have been albitized. Dissolution of calcite cement and of framework grain (feldspar, volcanic fragments and mud intraclasts) has resulted in a considerable enhancement of reservoir quality.
KW - Diagenesis
KW - Reservoir quality
KW - Sequence stratigraphy
KW - Shetland-Faroes Basin
KW - Tertiary
KW - Turbidites
UR - http://www.scopus.com/inward/record.url?scp=44649099508&partnerID=8YFLogxK
U2 - 10.1016/j.marpetgeo.2007.07.012
DO - 10.1016/j.marpetgeo.2007.07.012
M3 - Article
AN - SCOPUS:44649099508
SN - 0264-8172
VL - 25
SP - 514
EP - 543
JO - Marine and Petroleum Geology
JF - Marine and Petroleum Geology
IS - 6
ER -