AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Development of a Sand Injection Complex: Volund Field, Offshore Norway
(1) Marathon International Petroleum (G.B.) Limited, Aberdeen, United Kingdom.
The Volund Field lies in the Norwegian sector of the North Sea (Block 24/9). This field produces from a large-scale hydrocarbon-bearing sandstone injection complex in the Early Eocene section. The complex was identified from the seismic, which exhibits a Class 3 bright negative amplitude AVO anomaly. The first exploration well was drilled in 2004 on the Hamsun Prospect, and development drilling was completed in 2010. Volund Field is currently producing oil from four horizontal branches, with one water injector well, and has a common OWC and GOC.
Volund Field is unique in that the entire field is composed of a large-scale sandstone injection complex. The sandstone reservoir was originally deposited in a deep marine setting within the intra-Sele Formation Hermod Sand Member, and became re-mobilised and subsequently injected into the overlying stratigraphy. The lateral and vertical seal of the ‘Injection Trap’ are created by the juxtaposition of the injected sands against impermeable surrounding shale and mudstones of the Balder and Hordaland Formations. The Volund Field consists of a deeper central unit of stacked sandstone sills, which are surrounded by shallower, steeper dipping injected sandstone dikes (>20°, often called ‘wings’), such that the overall field shape resembles a large-scale ‘bathtub’ open to the west. The injected sands are an excellent reservoir with consistently high porosity and permeability. Many of the steeply dipping injected dikes appear to have excellent connectivity from the water leg up through the oil leg and into the gas cap.
The hydrocarbon-filled injectite sands at Volund exhibit a Class 3 AVO signature on the Far Offset reflection seismic volume. The seismic has been successfully used to locate horizontal production wells. Seismic geobodies have been extracted and incorporated into the reservoir geomodel to drive the geometry of the injectite features and to populate sands within the injection complex. The current reservoir geomodel also incorporates the vast horizontal well control (~5500m of reservoir section), available core, and outcrop analogue parameters. This Volund Field case study is an excellent, unique example of an economic producing sandstone injection complex.