New insights into salt tectonics in the northern Dutch offshore: a framework for hydrocarbon exploration

Abstract

The northern Dutch offshore is an area that has seen less hydrocarbon exploration activity than other areas of The Netherlands. Acquisition of a new regional 3D seismic dataset allowed further testing and re-evaluation of established geological concepts in this area. It is recognized that the presence and movement of Upper Permian Zechstein evaporites had a major impact on depositional patterns in Mesozoic sediments, structural development and hydrocarbon migration. As such, this study looks specifically at the role of salt tectonics in tectonosedimentary development. To assess this salt tectonic evolution within its structural context, a restoration of the Step Graben and Dutch Central Graben was performed. It follows that depositional patterns are closely linked to the nature of salt structure movement and the timing of regional tectonism. For example, during Late Triassic rifting, salt pillows developed and sedimentation focused away from salt structures into depocentres along regional fault trends. Restoration results show that this interplay between salt movement and tectonism is needed to accommodate the sedimentation patterns associated with the formation of the Step Graben and Central Graben during the Triassic and Jurassic, and later during Late Cretaceous and Cenozoic inversion tectonics.

Tectonostratigraphy of a rift basin affected by salt tectonics: synrift Middle Jurassic–Lower Cretaceous Dutch Central Graben, Terschelling Basin and neighbouring platforms, Dutch offshore

“…These minibasins are either due to Early Triassic progradational fluvial systems or to the relative proportion of marginal Zechstein facies compared to the amount of salt (as proposed for the UK sector minibasins by Stewart & Clark 1999). The main period of salt movement in the study area was the Middle and Late Triassic (Geluk 2007), and continued during the Jurassic and Early Cretaceous (van Winden et al 2018). The original depositional thickness of the salt layer was likely variable across the study area, with thicknesses ranging from 400 m in the south to a maximum of 900 m in the north Hernandez et al 2018).…”

“…The original depositional thickness of the salt layer was likely variable across the study area, with thicknesses ranging from 400 m in the south to a maximum of 900 m in the north Hernandez et al 2018). van Winden et al (2018) places the original thickness of the salt as high as 1500 m within the central part of the Dutch Central Graben. Thin-skinned normal faults formed during the Middle Triassic, detaching on the Zechstein salt.…”

“…salt bodies SB2 and SB3, Fig. 7; SB2 and SB3, Figs 10, 11) (see De Jager 2012;van Winden et al 2018).…”

“…Salt pillows, stocks and walls developed along the main bounding faults of the Dutch Central Graben during this period, and created a complex basin configuration and stratigraphy (e.g. van Winden et al 2018).…”

Mesozoic resource potential in the Southern Permian Basin area: the geological key to exploiting remaining hydrocarbons whilst unlocking geothermal potential

“…Ziegler 1990a;Verdier 1996;Geluk 2005;Peryt et al 2010;Fryberger et al 2011;McKie 2017). These evaporite sequences later (typically, from the Early-Mid Triassic onwards) mobilized into significant salt pillows, walls and diapirs which impacted Mesozoic depocentres and allowed hydrocarbon trap formation (as discussed by Bouroullec et al 2018;Hernandez et al 2018;van Winden et al 2018).…”