Diagenesis and reservoir-quality evolution of fluvial sandstones during progressive burial and uplift: Evidence from the Upper Jurassic Boipeba Member, Reconcavo basin, northeastern Brazil
Am. Salem et al., Diagenesis and reservoir-quality evolution of fluvial sandstones during progressive burial and uplift: Evidence from the Upper Jurassic Boipeba Member, Reconcavo basin, northeastern Brazil, AAPG BULL, 84(7), 2000, pp. 1015-1040
Citations number
54
Categorie Soggetti
Earth Sciences
Journal title
AAPG BULLETIN-AMERICAN ASSOCIATION OF PETROLEUM GEOLOGISTS
The reservoir quality of fluvial sandstones of the Upper Jurassic Boipeba M
ember, Reconcavo basin, northeastern Brazil, is highly heterogeneous and co
ntrolled by eodiagenesis under semiarid climate, mesodiagenesis during buri
al to a depth of 3500 m, and telodiagenesis due to local uplift. Eodiagenes
is resulted in mechanical compaction, calcite cementation, clay infiltratio
n, and limited grain dissolution, whereas mesodiagenesis resulted in the pr
ecipitation of calcite cement and quartz overgrowths, intergranular quartz-
grain dissolution, chloritization and illitization of smectite, and albitiz
ation of feldspars. Sandstones continuously buried at maximum burial depths
of about 1600 m (T = 65 degrees C) since 125 Ma display a relatively great
er degree of mesogenetic modifications and, on average, poorer reservoir qu
ality than sandstones that were buried deeper (2100 m, T = 75 degrees C) pr
ior to uplift, but only since 13 Ma. Uplift, which affected the sequence al
ong the western border of the basin, has resulted in telogenetic dissolutio
n of framework silicates and formation of kaolinite. Relatively good reserv
oir quality in the deeply buried sandstones occurs when (1) the grains are
coated with a thin layer of chloritized infiltrated smectite, (2) there is
little or no pseudomatrix, and (3) there are widely scattered patches of eo
genetic calcite cement that supported the framework of sandstones against c
ompaction.