Volund Field: development of an Eocene sandstone injection complex, offshore Norway

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.

An integrated model of clastic injectites and basin floor lobe complexes: implications for stratigraphic trap plays

“…Additionally, many of the large‐scale injectite networks in the Tertiary of the North Sea have maintained excellent reservoir properties (Hurst & Cartwright, ) and outcrop examples such as the Panoche Giant Injection Complex have been shown through fluid inclusion analysis to have maintained migration of fluid for almost 2 Ma post injection (Minisini & Schwartz, ; Hurst et al ., ). Besides acting as fluid migration pathways, clastic injectites can connect otherwise separate reservoirs, and form traps when injected solely into—or capped by—impermeable strata (Frey‐Martínez et al ., ; Schwab et al ., ).…”

Sedimentological evolution of Sele Formation deep-marine depositional systems of the Central North Sea

“…Hurst et al 2005Hurst et al , 2011. These features, where net rock volume is large enough, can form viable reservoirs (Schwab et al 2014). …”

Tertiary deep-marine reservoirs of the North Sea region: an introduction

“…Merganser: Charles & Ryzhikov 2015;Jones et al 2015); large-scale sand injection complexes (cf. Dixon et al 1995;Hurst et al 2005;Schwab et al 2014); isolated channel-form sandstones encased in shale (e.g. Alba: Moore 2014); large-scale compactional relief of the entire basin-floor fan (e.g.…”

“…At the extreme end of the scale are fields where the reservoir is entirely composed of injected dykes and sills. Schwab et al (2014) describe such an intrusive trap arising from the large-scale remobilization of Hermod Formation sandstones. Imaging of individual injected sandstones is an issue, but larger-scale intrusive complexes can be resolved.…”

“…Large-scale injection features have been identified in a number of fields (Dixon et al 1995;Huuse et al 2004;Schwab et al 2014) and outcrop descriptions enable some prediction of what subseismic architectures might be anticipated (Hurst et al 2003;Surlyk et al 2007;Vigorito et al 2008;Scott et al 2009). However, as mentioned above, the anomalous connectivity of some reservoirs that were expected to be stratigraphically compartmentalized could be the result of smaller-scale injection processes able to breach thin shale drapes and connect discrete sandbodies (Hurst & Cartwright 2007).…”