Abstract The Volund Field lies in the Norwegian sector of the North Sea (Quad 24/9). This field produces from a ‘classic’ large-scale sandstone injection complex located in Lower Eocene strata. The sandstone reservoir has been injected into the lower permeability surrounding mudstones of the Sele and Balder formations and Hordaland Group to create an ‘intrusive trap’. The Volund Field consists of a deeper central unit of stacked sandstone sills, surrounded by shallower, steeper-dipping injected sandstone dykes, which make excellent reservoirs with consistently high porosity and permeability. Many of the steeply-dipping injected dykes appear to have excellent connectivity from the water leg through the oil leg and into the gas cap. The complex was identified on seismic data that exhibit a Class 3 amplitude versus offset (AVO) signature on the far-offset stack reflection seismic volume. The seismic data have been used to successfully locate horizontal production wells. Volund seismic geobodies have been extracted and incorporated into the reservoir geomodel to determine the geometry of the injectite features and to populate sands within the injection complex. Volund Field (estimated mean gross resource of 54 mmboe (million barrels oil equivalent)) is producing oil from four horizontal branches (end December 2012), with one water injector well, and has a common oil–water contact and gas–oil contact.

Abstract Although the southern Front Range in Colorado Springs and Manitou Springs contains a near-complete record of Rocky Mountains geological evolution from Proterozoic to Present, there nevertheless are persistent geological problems that have eluded understanding for as much as 125 years. In keeping with the 2013 GSA Annual Meeting theme, “Celebrating Advances in Geoscience,” this field trip visits long-known elements of Front Range geology that merit reexamination within the context of new paleoenvironmental and geochronology data. Of note are: (1) the Great Unconformity and its chemically weathered substrate that correspond to a time of profound changes in global ocean chemistry; (2) lower Paleozoic strata that record sea-level fluctuations, attributable in part to regional tectonism; (3) an array of granite-hosted sandstone dikes, for which a new emplacement model is proposed; and (4) the Front Range monocline at Garden of the Gods Park, examined from the standpoint of its temporal evolution, newly bracketed by results of 40 Ar/ 39 Ar age analysis of illite generated by shear upon bedding-parallel faults.