VIMP Report 54 - Cretaceous source rocks of the onshore Gippsland Basin, Victoria
 |
| |||||
Product description:Download The downloadable version of this report is supplied in PDF format. Abstract This report documents the results of geochemical analyses and burial history reconstructions of Cretaceous source rocks in 10 Victorian onshore wells (sampled as part of the VIMP onshore Gippsland Basin Project). Although several organic rich horizons exist, the potential of Cretaceous source rocks to generate oil and gas onshore Gippsland has been found to be generally lower than offshore. The maturity of the Cretaceous source rocks in the onshore region, generally increases basinward within the Seaspray Depression. Gas-prone macerals usually predominate in the Strzelecki and Golden Beach Groups. Oil-prone macerals tend to be more abundant in the thicker, marginally-mature sediments. The peak time for the generation and expulsion of hydrocarbons within the onshore region of the basin was during the mid-Cretaceous. In general, there was only one distinct pulse of hydrocarbon expulsion, around 100 Ma. This is due to regional uplift during the Early Cretaceous, which hindered sedimentation during Late Cretaceous time. By contrast, towards the offshore area (Golden Beach West 1), two distinct phases of hydrocarbon expulsion occurred. The first event occurred between 115 to 95 Ma (late Early Cretaceous), and the second one during the 80 to 40 Ma period. This was due to rapid subsidence and associated structuring in the offshore area, resulting in a thicker Late Cretaceous and Tertiary section being deposited. These thick Tertiary units acted as a regional seal, and prevented the loss of hydrocarbons to the surface. Bibliographic reference Mehin, K. & Bock, M.P., 1998. Cretaceous source rocks of the onshore Gippsland Basin, Victoria. Victorian Initiative for Minerals and Petroleum Report 54. Department of Natural Resources and Environment. | ||||||
