Compartmentalization of the Nelson field, Central North Sea: evidence from produced water chemistry analysis

Abstract

Drainage cells are localized reservoir volumes that are bounded both laterally and vertically by permeability barriers. The subdivision of a reservoir volume into drainage cells provides a framework that allows a mature producing field to be screened for remaining oil volumes. Nine drainage cells have been defined in the Nelson field. The lateral edges of these drainage cells are stratigraphic in nature and correspond to the boundaries between individual macroforms, for instance, between channel complexes and interchannel sediments.A very large dataset of produced water chemical analyses has been used to help define the extent of the drainage cells. Provinciality, shown by areal variations in produced water compositions, is consistent with the inferred location of the cells. The Nelson field shows variation in the chloride ion concentration of produced water both vertically and laterally. Vertical variation can be detected by changes in produced water chemistry after water shut-off events at shale horizons which are thought to be laterally extensive within the reservoir. Lateral variation corresponds to patchwork areas that are consistent with individual macroforms such as channel complexes.An additional technique has been used to confirm the location and extent of drainage cells within the field. This involves the compilation of drainage charts, a quantitative volumetric method that involves comparing theoretical and actual oil–water contact changes within particular field areas.

Stratigraphic reservoir compartmentalization: causes, recognition, and implications for the geological storage of carbon dioxide

“…Vertical and lateral variations in the chloride ions of produced water enabled Gill et al (2010) to identify nine separate drainage cells in the Nelson field of the UK Central North Sea. These were controlled by stratigraphic compartmentalization by turbidite channel heterogeneity.…”

“…The term drainage cell was therefore used by Shepherd (2009) to describe situations where an orthogonal, intersecting fault system combines with stratigraphic barriers to create box-shaped reservoir intervals isolated by permeability barriers. However, Gill et al (2010) subsequently also applied the term to non-connected units within stratigraphically compartmentalized reservoirs.…”

EXTREME CAPILLARY HETEROGENEITIES AND IN SITU FLUID COMPARTMENTALIZATION DUE TO CLUSTERS OF DEFORMATION BANDS IN SANDSTONES

“…There are numerous examples of the impact of geologic structures on fluid compartmentalization in the subsurface (Gainski et al, 2010;Gill et al, 2010;Hansen et al, 2013;Milkov et al, 2007;Richards et al, 2010;Scott et al, 2010;Van Hulten, 2010;Rotevatn et al, 2017). Deformation bands have impacted production in several hydrocarbon reservoirs (for example, Antonellini et al, 1999;Leveille et al, 1997;Lewis and Couples, 1993;van Ojik et al, 2020).…”

Integrating geochemical and reservoir engineering approach to evaluate reservoir continuity: A case study from Foroozan field, Offshore Iran

“…In several papers, various methods have been used to evaluate reservoir continuity such as formation of water analysis (Gill et al 2010), geochemical fingerprinting (Kaufman et al 1990;Hwang and Baskin 1994;Smalley and Hale 1996), gas geochemistry (Beeunas et al 1999;Levachéet et al 2000;Márquez et al 2013), structural and stratigraphic continuity (Hovadik and Larue 2010), Fourier transform infra red (FTIR) and synchronous ultra violet fluorescence (SUVF) spectroscopy (Permanyer et al 2002(Permanyer et al , 2007 and formation pressure measurements (Páez et al 2010). However, in the recent years, the assessment of reservoir continuity using integrating geochemical and reservoir engineering approach has not been well documented.…”