Publication Name: The Cooper & Eromanga Basins Australia
Authors: P.J. Eadington, P.J. Hamilton and P. Green
Date Published: June 1989
Number of Pages: 32
Reference Type: Book Section
Abstract:
Stable isotope, fluid inclusion and chemical kinetic studies of diagenetic cements have been used to investigatethe thermal and liquid hydrocarbon history of Hutton Sandstone samples from eight wells in south-west
Queensland.
Fluid inclusion data, the current geothermal gradient and maturity measurements have been used as multiple
constraints to deduce a geothermal gradient of about 45 C in Cretaceous time for the Jackson-1 and Challum-1 wells. Chemical kinetic modelling of oil generation using the same gradient indicates Late Cretaceous to Early Tertiary oil migration. This is consistent with the occurrence of liquid hydrocarbon inclusions in quartz overgrowths indicating that oil migration was simultaneous with quartz cementation.
Isotope measurements show that siderite, the earliest formed cement, precipitated at 2o?c from parental
groundwater that was little modified in oxygen isotope composition from surface water at the time (o1BQ =
-13 ). The o1BQ composition of formation waters increased during subsequent kaolin formation and reached
-4.5 at 91 to ns?c during formation of quartz overgrowths. Subsequent uplift has changed fluid flow patterns as evidenced by the reversal in the 180 content of modern groundwaters to o180 about -7 at the present day.