Impact of Magmatism on Petroleum Systems in the Sverdrup Basin, Canadian Arctic Islands, Nunavut: A Numerical Modelling Study

Abstract

Numerical modelling is used to investigate for the first time the interactions between a petroleum system and sill intrusion in the NE Sverdrup Basin, Canadian Arctic Archipelago. Although hydrocarbon exploration has been successful in the western Sverdrup Basin, the results in the NE part of the basin have been disappointing, despite the presence of suitable Mesozoic source rocks, migration paths and structural/stratigraphic traps, many involving evaporites. This was explained by (i) the formation of structural traps during basin inversion in the Eocene, after the main phase of hydrocarbon generation, and/or (ii) the presence of evaporite diapirs locally modifying the geothermal gradient, leading to thermal overmaturity of hydrocarbons. This study is the first attempt at modelling the intrusion of Cretaceous sills in the east-central Sverdrup Basin, and to investigate how they may have affected the petroleum system.A one-dimensional numerical model, constructed using PetroMod9.0 ® , investigates the effects of rifting and magmatic events on the thermal history and on petroleum generation at the Depot Point eastern Axel Heiberg Island (79 o 23'40"N, 85 o 44'22"W). The thermal history is constrained by vitrinite reflectance and fission-track data, and by the tectonic history. The simulation identifies the time intervals during which hydrocarbons were generated, and illustrates the interplay between hydrocarbon production and igneous activity at the time of sill intrusion during the Early Cretaceous. The comparison of the petroleum and magmatic systems in the context of previously proposed models of basin evolution and renewed tectonism was an essential step in the interpretation of the results from the Depot Point L-24 well.The model results show that an episode of minor renewed rifting and widespread sill intrusion in the Early Cretaceous occurred after hydrocarbon generation ceased at about 220 Ma in the Hare Fiord and Van Hauen Formations. We conclude that the generation potential of these deeper formations in the eastern Sverdrup Basin was not likely to have been affected by the intrusion of mafic sills during the Early Cretaceous. However, the model suggests that in shallower source rocks such as the Blaa Mountain Formation, rapid generation of natural gas occurred at 125 Ma, contemporaneous with tectonic rejuvenation and sill intrusion in the east-central Sverdrup Basin. A sensitivity study shows that the emplacement of sills increased the hydrocarbon generation rates in the Blaa Mountain Formation, and facilitated the production of gas rather than oil. INTRODUCTIONExploration geologists commonly develop numerical models based on source-rock properties such as thickness, thermal conductivity, porosity, permeability,

Numerical modelling of the hydrocarbon generation of Tertiary source rocks intruded by doleritic sills in the Zhanhua depression, Bohai Bay Basin, China

“…Igneous intrusions can remarkably change the generation, migration and accumulation of hydrocarbon in a petroleum‐bearing basin. The heat released from the igneous intrusion can trigger hydrocarbon generation at a very shallow burial depth (Galushkin, ; Wu et al ., ; Jones et al ., ; Fjeldskaar et al ., ), and the processes would be complete in several thousand years (Simoneit & Kvenvolden, ; Simoneit et al ., ), which is much faster than the common behaviour in basins with a normal geothermal gradient. Furthermore, the fractures and various pores develop in the intrusive during the magma cooling, and the metamorphic pores in the hornfels provide abundant space for oil accommodation (Wu et al ., ).…”

Stratigraphic and Spatial Extent of HALIP Magmatism in Central Spitsbergen

“…Jones et al. (2007) conduct 1D basin modeling and illustrate that enhanced heat flow related to HALIP magmatism contributed to enhanced hydrocarbon production in otherwise immature shallower source rocks, contributing primarily to gas production within the metamorphic aureoles.…”

Intrusion of Magmatic Bodies Into the Continental Crust: 3‐D Numerical Models

“…Magma emplacement in the shallow crust is of major importance for secondary effects such as the formation of mineral deposits (e.g., of porphyry‐copper type), geothermal fields, the maturation of hydrocarbon reservoirs in sedimentary basins (e.g., Jones et al, ), and even climate change through the release of significant volumes of greenhouse gases (Svensen et al, ). In the uppermost kilometers of the crust, magma emplacement reflects the brittle behavior of crustal rocks (Fyfe, ) influenced by the closeness to the free surface (Hutton, ).…”