Origin of the Magnetic Signature of Hydrocarbons

From aeromagnetic surveys there is evidence of large magnetic anomalies around some hydrocarbon reservoirs. Direct sampling of cores from Venezuela, China and the US has revealed the presence of an abundance of distinctive magnetite framboids at these anomalies, however, we still do not understand how these magnetic minerals form and how they relate to the hydrocarbons.
If we can understand the formation mechanisms and environment, and the migration behaviour of these magnetite framboids, then this has the potential to will help us to better understand hydrocarbon reservoirs. This cross-disciplinary proposal aims to understand these processes.
In a preliminary study, to test for the universality of these magnetic signatures, we have already studied samples from the oil sand out-crops near Wytch Farm oil field, Dorset, from the North Sea core repository at the BGS in Edinburgh, from Athabasca, the Alberta basin, Canada, and Llanos Foreland, Columbia. Within these samples we have found magnetic framboids and a direct correlation between the abundance of magnetic minerals determined by the magnetic susceptibility and organic matter content.
However, there are a number of key questions, which as yet remain unanswered, which are important if we are to apply mineral magnetic techniques to hydrocarbon research: 1) What is the origin of the magnetic minerals?, 2) What is the relationship between the biodegradation state of oil and the magnetic signature?, and 3) Do the magnetic minerals migrate, and if so, 4) can we identify the migration distance? As part of this proposal we plan to answer these questions.
To address our objectives, we aim to complement our suite of samples with samples Wytch Farm drill cores (BGS core store at Keyworth) and with bitumen from the celebrated Tar Tunnel in Shropshire, UK. The samples from Shropshire will be collected from a different sections so that migration paths can be assessed.
The plan of research plan combines magnetic and scanning and transmission electron microscopy of the samples to determine the abundance, morphology, size and mineralogy of the magnetic minerals, with gas-chromatography mass spectrometry and other chemical analysis.
Migration processes will be determined by sampling through an oil reservoir. If the magnetic minerals migrate, then it is likely that the greater framboids will travel a greater distance than the smaller ones. Given that magnetic properties are highly dependent on magnetic grain-size, we aim to determine a magnetic proxy to identify migration distance.

Main Beneficiaries

The main beneficiaries are likely to be academics and companies working in hydrocarbon extraction and recovery, though an improved understanding of oil biodegradation and migration.
Other potential beneficiaries are scientists who study bacteria and biodegradation process in sediments. This group includes palaeoclimatologists, life scientists, ecologists, geologists etc.
Lastly, scientists studying remagnetisation processes, which can be used to understand a wide range of geological events from ore deposit formation to 'Snowball' earth.

Engagement activities

We will engage with these beneficiaries using the standard channels, i.e., presentation of our research at specific conferences like the American Association of Petroleum Geologists (AAPG) annual meeting, and peer-reviewed journals.

We will also use the established links between The Department of Earth Science and Engineering at Imperial College London and a number of oil companies. We will discuss our project with our contacts, and if there are potential economic benefits from this research, then with the help of Imperial Innovations we will apply for appropriate patents. Co-I Prof. Mark Sephton has already successfully applied for a number of patents.

We also intend to publicise our results via a freely distributed newsletter. Such a publication is already exists, called the 'IRM Quarterly' that is edited and freely distributed worldwide to the palaeomagnetic and geomagnetic community by the Institute of Rock-Magnetism at the University of Minnesota. Additional advertising of the projects aims and objectives, and the presence of the rockmag.net website will be done through the Geomagnetic and Palaeomagnetic community list server (https://mailman.ucsd.edu/mailman/listinfo/gpmag-l).

Other methods to disseminate information:

1) In year two we will submit a proposal to the Royal Society Summer Science Exhibition.

2) Day-to-day aspects of the project will feature on Imperial College's Department of Earth Science and Engineering's "Hot Topics" website articles page: http://www3.imperial.ac.uk/earthscienceandengineering/aboutese/hottopic.
and the palaeomagnetism website:
http://www3.imperial.ac.uk/earthscienceandengineering/research/geophysics/palaeomagnetism

3) Major findings will be disseminated through the Imperial College London press office.