Study details a glance
Biostratigraphy
Review
New
Biostratigraphy
Analyses
Palaeoenvironments
& Facies
56
Wells
Palaeocene
Eocene
Key points
- Objectively resolves the inconsistent lithostratigraphic assignment of various ‘Rogaland sands’ reported on many composite logs, while also introducing a Bittern Sandstone Member and Gannet Sandstone Member
- 1,200 new palynological analyses and >500 new micropalaeontological analyses across 56 wells
- PetroStrat have long been considered the most experienced stratigraphic specialists on this Tertiary section
PetroStrat invites companies seeking to better understand and evaluate the prospectivity of the Eocene and Paleocene aged sands in the southern part of Quad 22 and northern parts of Quads 28, 29 and 30 to participate in a regional 50+ well non-proprietary biostratigraphic study. The principal study objective seeks to help differentiate the numerous aged sands within both the Sele and Lista Formations to facilitate improved seismic mapping and reservoir characterisation. Since the discovery of the Catcher Field in 2010 (followed later by the Varadero, Burgman, Carnaby and Bonneville satellite discoveries) there has been renewed interest in the prospectivity of Eocene-aged sands within the northern part of Quads 28 and 29. More recently, the Vorlich/Marconi discovery in block 30/1f has helped extend this interest further to the east and has created further discussion as to the precise age and origins of some of these locally developed/ channelised high net/gross sands across the region.
Background
The terms ‘Rogaland Sandstone’ and ‘Cromarty Sandstone Member’ have been widely used for sands deposited within the Sele Formation in the quad 28/29 area. However, whilst the former has been applied to any undifferentiated sand body within the Sele Formation the latter, which by definition should be reserved for sands deposited within Unit S2b, has been widely misapplied. The application of a high-resolution palynological zonation across the ‘earliest’ Eocene and Paleocene promotes very precise age control that allows for the identification of numerous discrete sand bodies. These sands include those deposited within the basal part of the Balder Formation, within the S3 Unit at the top of the Sele Formation and within the S2a Unit above the S1 restricted Forties Sandstone Member. Few instances of true S2b (Cromarty) sands have been observed in the area. The reservoir potential of Unit S2a sands is exemplified in the Bittern Field (block 29/1), whilst the reservoir potential of basal Balder and Unit S3 sands is well observed to the north across the Gannet D Field.
Sands/Reservoirs
The Forties Sandstone Member provides an important reservoir across some of the Gannet fields and to the south and east (e.g. at Starling and Fram). It is also a significant reservoir in the south eastern portion of Quad 22 and in to Quad 23 where the Lomond, Columbus, Scoter and Pierce Fields are situated, albeit that the sands at these localities are largely sourced from the main Forties fan extended down the Eastern trough of the Central Graben from a more north westerly directly. This study will seek to break out all 11 of the PetroStrat F-units within the Forties (Units S1b – S1a).Sands within the Late Paleocene aged Lista Formation are also prospective across the study area. They are being exploited at Stella (block 30/6) and across J Block (30/7). However, accurately dating these sands has proven challenging across much of the area, especially in the east, due to the prevalence of reworking from the Maureen Formation (and Chalk) both above and below the sands.
Study Deliverables
- The study will provide a biostratigraphic database for 50+ wells with a focus on the interval from within the Balder Formation to the upper part of the Maureen Formation. The fossil data will be interpreted, zones applied and lithostratigraphic and sequence stratigraphic picks incorporated in to the stratigraphic summary charts. A set of regional correlations will be included in the report.
- The study will include over 1200 new palynological analyses and over 500 new micropalaeontological analyses with sampling targeted to help resolve stratigraphic ambiguities.
- All data will be available digitally as .csv files, StrataBugs dex files, tops tables and as an ODMTM project inclusive of correlations.
- Interim data sets will be provided to companies that pre-commit to the study at regular intervals, commencing with a data package incorporating all the wells already worked (the study was initiated in Q3 2015).
