Abstract The Edradour Field, located in Licence P1453 on Block 206/4a of the Faroe–Shetland Basin, was put on production in August 2017. It lies c. 50 km NW of the Shetland Islands in a water depth of c. 300 m, and consists of one subsea well that produces gas condensate from the Albian Black Sail Member of the Commodore Formation. It is part of a joint development scheme along with the Glenlivet Field that sees the commingled multiphase production transported to the Shetland Gas Plant via tieback to the pre-existing Laggan–Tormore flowlines. The Edradour single well development has reserves of 21 MMboe from a gas initially-in-place of 142 bcf. It is operated by Total E&P UK Ltd under the P1453 licence with Ineos E&P (UK) Ltd and SSE E&P UK Ltd as partners.

Abstract The Glenlivet Field, located in Block 214/30a within the Faroe–Shetland Basin, was put on production in August 2017. It lies approximately 70 km NW of the Shetland Islands, in a water depth of c. 440 m. The development consists of two subsea wells that produce gas condensate from the Paleocene Vaila Formation, which comprises deep-water turbidite deposits with excellent petrophysical properties. It is part of a joint development scheme along with the Edradour Field that sees the commingled multiphase production transported to the Shetland Gas Plant via tie-back to the pre-existing Laggan–Tormore flowlines. Glenlivet is operated by Total E&P UK Ltd under the P1195 licence since September 2014 with Ineos E&P (UK) Ltd and SSE E&P UK Ltd as partners.

Abstract The Laggan and Tormore fields are found within the Flett sub-basin of the Faroe–Shetland Basin. Situated 120 km west of the Shetland Islands in 600 m water depth, they are part of the deepest subsea development in the UK to date with a 143 km subsea tie-back to onshore facilities. The reservoirs are found within the T35 biostratigraphic sequence of the Paleocene Vaila Formation and comprise sand-rich turbiditic channelized lobes with good reservoir properties, separated by metric to decimetric shale packages. Laggan is a gas-condensate field, whereas Tormore fluid is a richer gas with a saturated oil rim. Seismic reservoir characterization is a key to the field development where differentiation of fluid type proved challenging. Both fields came on stream in 2016 as part of the Greater Laggan area development scheme.

Abstract Spectral decomposition analyses seismic reflectivity data in the frequency domain, providing images of the subsurface that complement conventional seismic interpretation. It is a highly visual tool that allows additional value to be extracted from seismic data, to aid in the identification of geological information and to be used in conjunction with more traditional methods such as amplitude extraction and attribute analysis. The methods of spectral decomposition chosen utilized a top reservoir seismic reflection surface, with the selected dominant frequency volumes coloured and recombined in a spatial context to produce various red–green–blue (RGB) blends. Application of spectral decomposition to the Laggan and Tormore fields revealed the varied distribution of turbiditic sands, as well as extensive east–west faults that have previously been inferred from seismic reflection data. These enhanced images of the reservoir provide a more detailed interpretation of the field architecture and have been captured in DONG E&P UK Ltd's own fault and reservoir models, leading to a greater understanding of potential field development outcomes and future well placement decisions. Attempts to distinguish hydrocarbon effects using spectral decomposition proved difficult, although interesting frequency variations around a known gas–oil contact (GOC) were noted.

Abstract A seismic amplitude anomaly has been identified at the Upper Paleocene T38 level in the northern Judd Basin and will be tested by the drillbit in 2009. Prospectivity at shallower levels has been largely ignored due to the fact that the main regional seal in the area was recognized to be the T35/T36 mudstones below the Kettla Tuff. Seismo-stratigraphic analysis of the T38 sequence directly above the tuff marker has identified the potential for a new play type, especially adjacent to fault zones where these mudstones are breached, allowing hydrocarbons to migrate from the Upper Jurassic source kitchen into any traps identified above the seal. In this area, the T38 is represented by a series of northerly prograding low-angle clinoforms representing the final marine infill of sediments into the basin from the south. Erosion of top sets in a more marginal setting is observed, along with deposition of basin floor fans at the toe of the prograding clinoforms. The overlying seals are basinal sediments as well as mudstones and siltstones of subsequent progradational sequences. Mild structural modification of potential stratigraphic traps in the Judd Basin occurred during the Oligo-Miocene inversion associated with continued opening of the North Atlantic. Drilling seismic amplitude anomalies in the West of Shetlands area has often been unsuccessful. Therefore, a fully integrated geophysical and geological evaluation was carried out on the T38 anomaly comprising rock physics, amplitude variation with offset analysis, fault seal analysis and the acquisition of a CSEM survey which, supported by a valid geologic model, have reduced the risk from high to moderate. The results indicate that the anomaly has the potential to be sand-bearing and contain oil and gas. It is proposed that an integrated evaluation can reduce the level of uncertainty associated with an anomaly much more effectively and so improve the chance of exploration success.

Abstract Laggan, located in the west of Shetland, was discovered in 1986. There is now an improved understanding of Laggan, thanks to innovative and fully integrated geoscience studies and a successful appraisal campaign. Development studies are well advanced, with the discovery of Tormore in 2007 providing the potential for a combined development project. Laggan and Tormore are Paleocene gas condensate discoveries in approximately 600 m water depth. The traps are both mixed, stratigraphic with updip closure against bounding faults. The reservoir comprises sand-rich turbidite channelized lobes and lobes. Reservoir properties are good (permeability range 30–300 mD) due to the presence of chlorite and pre-sorting on the shelf. The geoscience evaluation of Laggan has matured over the last four years with the help of fully integrated studies using 3D seismic and well data. The depositional model has been defined on the basis of an evaluation of cores and seismic and supported by analogue studies. Seismic inversion studies have also helped constrain the reservoir architecture. Of particular value has been the application of AVO to quantify net gas sand, recognized as the principal static uncertainty. The main dynamic uncertainty is the risk of compartmentalization. This risk has been reduced through an improved definition of the fault configuration by re-processing the seismic and detailed seismic attribute analysis. The potential of Tormore was recognized by applying the geoscience understanding of Laggan to help de-risk the prospect. In particular, it was recognized that Laggan could be used as an analogue for the Tormore trapping configuration and reservoir potential and that AVO could be used to help define the Gas–Water Contact. The exploration well, drilled in 2007, was successful in finding a similar reservoir to that encountered in Laggan. The fluid encountered was a gas condensate, approximately three times richer than Laggan.