The Volund Field - Developing a Unique Sand Injection Complex in Offshore Norway (SPE 154912)

The Volund Field, in offshore Norway, is unique in being composed entirely of a large-scale sandstone injection complex. It consists of stacked sandstone sills, surrounded by shallower, steeper dipping injected sandstone dykes (>20CB0). The sands are excellent reservoir with consistently high porosity and permeability. Based on seismic, good connectivity was expected within the injectites from the water leg through the oil and into the gas cap. However, pre-production the extent of aquifer support and efficiency of water sweep were unclear. The Early Eocene complex was identified from seismic, which exhibits a Class 3 negative amplitude AVO anomaly. Development drilling began in 2009. The team strove to build a simulation model that allowed rapid generation of multiple realisations to investigate the effects of geological uncertainty on recovery, whilst honouring the AVO data. Geobodies extracted from seismic captured the geometry of the injectite. By populating these core bodies and surrounding C"halosC" with sands of varying properties within a geomodel, a series of realisations were built. Simulation modelling was employed to complete a dynamic uncertainty study and understand the potential effects of connectivity on aquifer and injection support. Drilling of four horizontal production branches and one injector was successfully completed in 2010 giving ~5500m of well control. Production began in April 2010 and 18 months of plateau production have demonstrated good communication. The reservoir benefits from aquifer support, but requires injection to maintain pressures. To date, no water has been produced, suggesting sweeps efficiencies in the upper half of our uncertainty range. This case study presents a modelling method based on seismic attributes which allows very quick generation of realisations that focus variation where there is the most uncertainty. This was key to the successful development of the Volund Field, a unique example of an economically producing sandstone injection complex.