Abstract The Rubie Field is located within the Outer Moray Firth in Block 15/28b, towards the eastern end of the Renee Ridge and 6 km east of the Renee Field. The block was awarded to a BNOC-operated group following the 7th Licensing Round in 1980. The 15/28b-4 discovery was drilled by Britoil in 1985, encountering hydrocarbons at two stratigraphic levels within the Paleocene Andrew Sandstone unit and Eocene Cromarty Sandstone Member reservoirs. No further appraisal was undertaken prior to a late 1997 Annex B submission for a joint Renee and Rubie Field development by new operator, Phillips Petroleum. The Rubie development plan comprised a single 6000 ft Andrew Sandstone horizontal producer which was completed in March 1999 and tested at an initial rate of 9700 bopd and 1.65 MMscfgd. Export of fluids was via a 6 km-long pipeline to the Renee Field manifold and then onwards to the host facility in the Ivanhoe–Rob Roy fields. Rubie was brought on stream on 29 May 1999. Abandonment was originally scheduled for end 2006, but field-life extension initiatives deferred cessation of production (COP) to March 2009. Cumulative Andrew Sandstone production at COP was 11.5 MMbbl and the oil recovery factor 50%, based on a final mapped oil-in-place of 23 MMbbl.

Abstract The Ivanhoe, Rob Roy and Hamish Fields lie in the Moray Firth of the UKCS in Block 15/21 and contain undersaturated oil trapped in the prolific Upper Jurassic Piper reservoir in tilted fault block traps. The fields were brought on stream in 1989 and since then the reservoir model has undergone several revisions with changes to the calculated oil in place volumes. The two main areas of uncertainty in the geological model are the position of the faults and the distribution of permeability. Improvements in the quality of the seismic data and the well ties brought about greater confidence in the seismic pick at top reservoir and the placement of the major bounding faults to the fields. The reservoir is generally sand-prone with a high net to gross ratio, porosity and permeability, which suggest that the reservoir would behave in a fairly homogeneous manner to fluid flow. Detailed reservoir description shows that this is not always the case. Improvements to the geological model permit a better understanding of the connection between the injector and producer wells and the degrees of influence from faults and heterogeneities in the reservoir to the fluid flow. Based on the current model the present recoverable reserves are estimated to be 187 MMBBL.