| Computer Code: |
PIPR |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Oxfordian Age (JO)
— Kimmeridgian Age (JD) |
| Lithological Description: |
The Piper Formation comprises fine- to coarse-grained, poorly cemented sandstone units, interbedded with sporadic dark, marine mudstone. Very thin coals have also been reported. The sandstone is mainly quartz-arenitic, but it becomes more feldspathic and arkosic and subarkosic in western quadrants. Concentrations of heavy minerals (e.g. zircon) and glauconite may produce anomalously high gamma values. It can be divided into five lithofacies:
Bioturbated, fossiliferous marine mudstone, with thin (1-2 m), poorly sorted, very fine-grained glauconitic sandstone at their base.
Bioturbated, silty, fine-grained sandstone with bivalve and belemnite fragments.
Well sorted, massive to cross-bedded, bioturbated, medium grained sandstone with sporadic shelly debris.
Well sorted, massive to planar bedded, coarse-grained sandstone.
Upward-fining, very coarse- to coarse-grained, cross-bedded sandstone.
In many wells the lithofacies are arranged in large-scale upward coarsening cycles up to c. 100 m thick, with upward-decreasing gamma-ray log profiles. In other wells (e.g. Highlander Field) the formation is dominated by more uniform sandstone successions. In the Ivanhoe and Rob Roy fields, thin upward fining sandstones (up to 5 m thick) occur.
The formation is divided into two members (Pibroch and Chanter members) which are separated by a shale, often informally termed the 'I Shale'.' |
| Definition of Lower Boundary: |
The lower boundary is characterised by a downward change from sandstone (Piper Formation) to mudstone (Heather Formation). In some sections there is a sharp down-section increase in gamma values across the boundary, but in others the change is more gradational. Locally, sandstone rest on coals or coal-bearing mudstone (Stroma Member of the Pentland Formation) or unconformably on volcanics (Rattray Volcanics Member of the Pentland Formation). |
| Definition of Upper Boundary: |
The upper boundary is commonly characterised by a downward change from mudstones or siltstones (Kimmeridge Clay Formation) to sandstones. Locally, sandstone of the Claymore Sandstone Member overlies the sandstones of the Piper Formation making recognition of the boundary difficult. However, mudstones interbedded with the sandstone of the Claymore Sandstone Member are generally darker in colour, less calcareous and more carbonaceous than those of the Piper Formation. |
| Thickness: |
Generally 100 to 200 m thick, but reaching 300 m around the north eastern end of the Halibut Horst. |
| Geographical Limits: |
Witch Ground Graben, Dutch Bank Basin, Halbut Shelf and northernmost South Halibut Basin; North Sea Quadrants 7, 8, 13-15, 21. |
| Parent Unit: |
Humber Group (HMBG)
|
| Previous Name(s): |
Piper Sand
(-5111)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
North Sea well 15/17- 4 at (revised) depths 2574-2655 m (Deegan and Scull, 1977; Richards et al., 1993). |
| Reference Section |
North Sea well 15/16- 9 at 3652.5-3879 m depth (Richards et al., 1993). |
| Reference Section |
North Sea well 15/17- 9 at 3939-4112.5 m depth (Richards et al., 1993). |
| Reference Section |
North Sea well 15/21a- 15 at 3383.5-3529.5 m depth (Richards et al., 1993). |
| Reference(s): |
| Waters, C N, Gillespie, M R, Smith, K, Auton, C A, Floyd, J D, Leslie, A G, Millward, D, Mitchell, W I, McMillan, A A, Stone, P, Barron, A J M, Dean, M T, Hopson, P M, Krabbendam, M, Browne, M A E, Stephenson, D, Akhurst, M C, and Barnes, R P. 2007. Stratigraphical Chart of the United Kingdom: Northern Britain. (British Geological Survey.) |
| Richards, P C, Lott, G K, Johnson, H, Knox, R W O'B. and Riding, J B. 1993. 3. Jurassic of the Central and Northern North Sea. In: Knox, R W O'B and Cordey, W G (eds.). Lithostratigraphic nomenclature of the UK North Sea. British Geological Survey, Nottingham. |
| Deegan, C E and Scull, B J. 1977. A standard lithostratigraphic nomenclature for the Central and Northern North Sea. Report of the Institute of Geological Sciences, 77/25; NPD Bulletin No.1. |
| Boldy, S A R, and Brearly, S. 1990. Timing, nature and sedimentary result of Jurassic tectonism in the Outer Moray Firth. 259-279 in Tectonic events responsible for Britain's oil and gas reserves. Hardman, R F P, and Brooks, J (editors). Special Publication of the Geological Society, London, No.55. |
| Coward, R N, Clark, N M and Pinnock, S J. 1991. The Tartan Field, Block 15/16, UK North Sea. In: Abbotts, I L (ed.) United Kingdom oil and gas fields, 25 years commemorative volume. Memoir of the Geological Society, London, 14, 377-384. |
| Harker, S D, Mantel, K A, Morton, D J and Riley, L A. 1993. The stratigraphy of Oxfordian-Kimmeridgian (Late Jurassic) reservoir sandstones in the Witch Ground Graben, UK North Sea. American Association of Petroleum Geologists Bulletin, 77, 1693-1709. |
| Maher, C E. 1981. The Piper Oil Field. In: Illing, L V and Hobson, G D (eds.) Petroleum Geology of the continental shelf of North West Europe, 358-370. [Heyden & Son, London] |
| O'Driscoll, D, Hindle, A D and Long, D C. 1990. The structural controls on Upper Jurassic and Lower Cretaceous reservoir sandstones in the Witch Ground Graben, UK North Sea. In: Hardman, R F P and Brooks, J (eds.) Tectonic events responsible for Britain's oil and gas reserves. Special Publication of the Geological Society, London, No.55, 191-205. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
| none recorded or not applicable |
