Exhumed hydrocarbon traps in East Greenland: A comment on Andrews et al. (2020)

Abstract

In a recent study, Andrews et al. (2020) describe "exhumed hydrocarbon traps" in NorthEast Greenland. The basic premise for their interpretation is that dark-coloured, pyrobitumen-bearing sandstones represent the remnants of once buried petroleum reservoirs. We do not see the necessary field or analytical evidence to support a model that has strong implications for resource evaluations. Andrews et al. (2020) have not considered previous published information on diagenetic and thermal maturity history of the area. A more probable model would include the intrusion of dykes and sills into a sedimentary succession with immature petroleum source rocks and reservoir-quality sandstones. The heating caused rapid generation of petroleum components and local hydrothermal circulation systems in adjacent porous sandstones. Any petroleum was rapidly destroyed leaving essentially only black grain-coatings and minor particles of pyrobitumen-essentially in one short-lived continuous process. The existence of new plays in the North Atlantic as proposed by Andrews et al. (2020) is in our opinion not substantiated as this requires analytical data from unaltered oils from the less mature parts of the sedimentary succession and considerations of thermal maturity and basin evolution. To draw conclusions that have a serious impact on resource evaluations based on the dark colouration of sandstones without comprehensive analytical data is, in our opinion, ill advised.

Exhumed hydrocarbon traps in East Greenland: Reply to Christensen et al.'s comment on Andrews et al. (2020)

“…Christansen et al. (2020) have raised concerns over the validity of the data and interpretation in our study of the exhumed hydrocarbon traps of East Greenland. Furthermore, they have put forward a model which they suggest that better suits their data.…”

“…These areas of investigation, concerning the maturity of source rock intervals, the effect of intrusive heating and the timing of proposed migration events are certainly worthy of further perusal but they do not rule out the proposed exhumed hydrocarbon trap model, indeed, many of the same points could be levelled at the model proposed by Christansen et al. (2020). What evidence exists that ties the alleged patchy pyrobitumen occurrences to intrusive activity?…”

“…Christansen et al. (2020) discount the evidence presented for the distribution of pyrobitumen (Andrews et al., 2020, figure 8), noting that they have not recognised this distribution elsewhere in Traill Ø. This is put forward from ‘decade‐long experience’, but unpublished accounts, of the region and primarily the work of Therkelsen (2016).…”

“…The need for a detailed diagenetic study as suggested by Christansen et al. (2020) is undoubted. This is a key in understanding the genesis of the palaeo‐hydrocarbon accumulations that we document but does not alter the evidence presented that these accumulations existed.…”

“…A number of points made by Christansen et al. (2020) can be considered as relating to the maturity of the proposed source rocks and the degraded hydrocarbons recognised in the reservoir rocks. First, it is suggested that traces of non‐degraded hydrocarbons should be present out with the areas of igneous impact.…”