Abstract
High-pressure/high-temperature wells are traditionally very challenging for biostratigraphical analyses. The temperatures achieved cause the organic matter to become highly mature and palynomorphs are altered, to an extent that can make identification extremely challenging. This study compares two wells and shows that the type of drilling bit and the control of drilling parameters can have a positive impact in the palynology recovery. Both wells are studied for palynology and the well with the best drilling parameters yielded generally good recovery, and although the palynomorphs also exhibit a high thermal maturity, it was possible to confidently identify enough palynomorphs to define the age of the penetrated sediments. The biostratigraphy study reveals a Rhaetian – Early Toarcian dataset from a complete stratigraphic succession that wasn't previously recorded in the Central North Sea. A lithostratigraphic unit is yet to be defined to characterise the sediments interpreted in this paper. The ecological analyses, using statistical methods, assessed the temporal and spatial variations in vegetation and palaeoenvironments. They focused on the Early Jurassic and indicate that during this time the landscape was diverse with a variety of habitats occupied by terrestrial plants dominated primarily by swamp and xerophyte types living near the coastal area.
Original language | English |
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Article number | 105249 |
Number of pages | 10 |
Journal | Marine and Petroleum Geology |
Volume | 132 |
Early online date | 26 Jul 2021 |
DOIs | |
Publication status | Published - 1 Oct 2021 |
Bibliographical note
Funding Information:Permission to publish the data and interpretations herein was kindly provided by Shell UK Ltd. and their partners Esso Exploration and Production UK Ltd. and BP. The interpretations and opinions presented here are those of the authors only and do not in any way represent the views of Shell UK Ltd. or Esso Exploration and Production UK Ltd. Also thank you to James Watson, Peter Nash and Matthew Hale for their help with interpreting drilling data, Tom McKie for the sedimentology information, Malcolm Jones for the sample processing and Marc Gordon for support with Arc GIS. Many thanks also to the referees for their constructive comments and suggestions for improvement.
Data Availability Statement
Supplementary data:Supplementary data to this article can be found online at https://doi.org/10.1016/j.marpetgeo.2021.105249.
Keywords
- Detrended correspondence analysis (DCA)
- Drilling
- Jurassic
- Palynology
- Stratigraphy
- Triassic