Abstract Enormous volumes of gas (>30 Tcf) are contained within the deepest portions of the Western Canada Foreland Basin, where tight gas-saturated Cretaceous sandstones grade updip into porous water-saturated sandstones. Production has occurred from coarse-grained shoreline sands both near the updip gas–water interface, such as those found in the Elmworth Field, and from low-porosity–permeability reservoirs found deeper in the basin. These basin-centred gas (BCG) reservoirs are characterized by regionally pervasive gas-saturated lithologies, abnormal pressures and no downdip water contact, and occur in low-permeability reservoirs. The keys to Shell's exploration success were an understanding of the stratigraphy, sedimentology and rock properties of the basin, the development of structural, petrophysical and geomechanical models, development of an understanding of the desiccation or dewatering process, the distribution of water within the basin and how the pressure regime evolved, interpretation of 3D seismic, and an aggressive land strategy. The evaluation of structural leads was aided when seismic and geomechanical modelling were combined, thereby aiding in the prediction of zones with a higher probability of encountering favourable reservoir producibility characteristics, that is, areas where a well developed, well connected open fracture network is expected. This multidisciplinary approach has resulted in economic success in regions once thought to be non-productive, and where it was once said, ‘People go broke chasing the Nikanassin’.

Sediment provenances and magmatic events of Late Neoproterozoic (Ediacaran) and Cambro-Ordovician rock complexes from the Saxo-Thuringian zone are constrained by new laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U-Pb dating of detrital zircons from five sandstones and magmatic zircons from an ignimbrite and one tuffite. These geochronological results in combination with the analysis of the plate-tectonic setting constrained from field observations, sedimentological and geochemical data, and trends of the basin development are used to reconstruct Cadomian orogenic processes during the Late Neoproterozoic and the earliest Cambrian. A continuum between Cadomian orogenesis and the opening of the Rheic Ocean in the Cambro-Ordovician is supported by the data set. In our model, the early stage of the Cadomian evolution is characterized by a Cordilleran-type continental magmatic arc, which was established at the periphery of the West African craton between ca. 650 and 600 Ma. Subsequently, at ca. 590–560 Ma, a back-arc basin was formed behind the Cadomian magmatic arc. The back-arc basin was closed between ca. 545 and 540 Ma, leading to the development of a short-lived Cadomian retroarc basin. Subsequently, a mid-oceanic ridge was subducted underneath the Cadomian orogen. Slab break-off of the subducted oceanic plate resulted in increased heat flow, leading to voluminous magmatic and anatectic events that culminated at ca. 540 Ma. Oblique incision of the oceanic ridge into the continent caused the formation of rift basins during the Lower to Middle Cambrian. This process continued from the Middle to Upper Cambrian, finally caused the opening of the Rheic Ocean in the Lower Ordovician.