12/11/18

David Gardiner from IGI to present a poster at the “PETEX 2018" Conference in London on 27 -29 November 2018

The poster is entitled: “Calculated Radioactive Heat Production From Basement & Sediments: Implications For Basin & Petroleum System Modelling”

This work is in collaboration with Chemostrat Ltd., Siccar Point Energy, Global Exploration Services Ltd. and Portsmouth University.

Abstract: 

Current basin modelling methods have multiple uncertainties, of which calculating the amount of radioactive heat generation is a small but still important contribution to the thermal history of a basin.  Current techniques derive temperatures based on depth and heat generated from radioactive decay, dominated by the decay of isotopes of Potassium (40K), Thorium (232Th) and Uranium (238U&235U), combined with conduction and convection.  Basin modelling studies undertaken by the hydrocarbon industry within the UK often use a crustal heat flow value for the Paleozoic continental crust of c. 2.8 μW/m3. While this has been shown to be appropriate for hydrocarbon provinces such as the North Sea, in other areas of the UKCS the crust may be Proterozoic in age and consequently significantly colder. For example, onshore Lewisian rocks, analogous to the basement rocks found in Hurricanes Lancaster Field, West of Shetland, measured heat flow is closer to 1.7 μW/m3 (Khutorskoi & Polyak, 2016).  

It is, however, possible to model radioactive heat production when the concentration of K, Th, U and the rock density is known (e.g. Burton-Johnson et al., 2017 and references therein).  The abundance of these elements in nearly all lithologies is produced by standard laboratory analysis during the production of chemostratigraphic studies, therefore radioactive heat production can be calculated both quickly and cost effectively as a by-product of chemostratigraphy, helping maximise its value.  The impact of variable heat flow on hydrocarbon generation is yet to be extensively quantified in the Literature, although some studies are being undertaken (Mark et al., 2018). 

This paper seeks to demonstrate this by applying the published methods of establishing radioactive heat production (e.g. Burton-Johnson et al., 2017 and Rybach, 1988) from current elemental data across a variety of lithologies. Furthermore, where possible, this data will be compared to that calculated from wireline logs and assumed values to demonstrate the variation in both scale and data achieved by these methods and so reduce the error in basin modelling from uncertain radioactive heat data.  Revision of basin models with access to crustal heat flow values that are representative of the true geology, calculated in this study, may have an impact on the timing of generation and migration.  Thus helping to explain away some of the uncertainties and complexities of previous models that have been restrictive to risking exploration prospects in some areas of the UKCS, and indeed globally.”

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