Oligocene and Miocene sedimentation in NW Borneo

Yasir Said, Robert Hall & Peter Lunt (Petronas)

Aims

This project began in October 2016 and is concerned with sediments and stratigraphy of offshore Sarawak, Malaysia and correlations with onshore Sarawak. It will use seismic data to review basin models and use well samples to characterise light mineral and heavy mineral assemblages of sand samples. Detrital zircons will be dated. The main aim is to determine the provenance of Oligocene to Lower Miocene sediments and improve palaeogeographic models for the region.

Background

Thick Oligocene sands offshore have been interpreted as part of a delta system. However, it is implausible to have a delta prograde over 250 km in a very short time interval or for a delta to be almost 300 km from one end of the coastal plain to the other. A new model is required for these sediments, which were the reservoir and source rocks for recent discoveries, but we lack the basic data with which to build it.

Analysing samples from old and well-known wells will shed important light on the problem. Other plays that will be impacted by this research are the Stage III clastics of Sabah, usually thought of as sand-poor, but locally with oil and gas shows. If a model could indicate where these clastics are richer in sands, it may open up new plays. Some turbidite sand plays on the Sarawak border have never been properly evaluated, again due to lack of basic data.

Recent Papers –

Max Webb et al., 2020. Isotopic mapping reveals the location of crustal fragments along a long-lived convergent plate boundary. Lithos.

https://doi.org/10.1016/j.lithos.2020.105687

Max Webb et al., 2020. The history of Cenozoic magmatism and collision in NW New Guinea – New insights into the tectonic evolution of the northernmost margin of the Australian Plate. Gondwana Research.

https://doi.org/10.1016/j.gr.2019.12.010

Amy Gough et al., 2020. Mid-Cenozoic fluvio-deltaic to marine environments of the Salin Sub-basin, Central Myanmar. Journal of Asian Earth Sciences.

https://doi.org/10.1016/j.jseaes.2019.104143

Recent News –

Amy Gough and Max Webb attended the Restech 2.0 Virtual Reservoir Conference. Amy Gough presented new SEARG research on the pitfalls of light mineral studies for sedimentary provenance in tropical climates.

Amy Gough was awarded an honorary research fellowship of the British Geological Survey and continues to foster collaborative relationships between SEARG and the BGS.