Study details a glance
New
Biostratigraphy
Analyses
Reservoir
Geology
Palaeoenvironments
& Facies
35
Wells
Carboniferous
Key points
- A key new regional biostratigraphical and sedimentological context for any further studies in northern Britain
- Helps illustrates the distribution of depocentres, carbonate highs, and deeper basinal settings within time slices through the late Viséan and Namurian
- Quantitative new palynological analysis enhances biostratigraphic zonation of this section, and will aid exploration onshore as an unconventional reservoir target.
PetroStrat and MB Stratigraphy have completed a multi-client study on the shale-dominated lithologies of the Namurian and latest Viséan in the Carboniferous of northern England and North Wales.
Background
The late Viséan-early Namurian Bowland Shale was largely deposited in sediment starved basins between carbonate platforms. The shales are source rocks and potential unconventional reservoirs. Marginal areas received significant carbonate input, often in the form of turbidites. Deltas prograded across the area in the later Namurian, infilling initially with clastic turbidites and associated shales, and later with fluvio-deltaic sandstones. In addition to shale gas potential in the area, these heterolithic sediments have some potential to form localised conventional or fracture reservoirs. There is minor oil potential.
Outcrop sampling and analysis
Samples have been gathered from key outcrop sections of known age and stratigraphy, typically linked to goniatites/marine bands. These have been analysed for biostratigraphy (palynology). Results have been used to calibrate analyses of material from the key boreholes.
Project
The multidisciplinary study has refined the palynological biostratigraphy of the Namurian sequences through detailed new quantitative palynological analysis. The produced chronostratigraphy has been integrated with sedimentology, stratal thicknesses and facies distributions. It will aid exploration and exploitation of these sediments as a largely unconventional reservoir target.
Borehole sampling and analysis
The focus of the study was on 35 selected key well sections that cover the complete Namurian stratigraphy. These provide a regional biostratigraphical and sedimentological context for any further studies in northern Britain.
Interpretation of Data
Biostratigraphical results have been tied back to lithological, e-log and sedimentological data where these are available. A series of regional cross-sections and palaeogeographical and facies maps have been generated. Indications of natural fractures and hydrocarbon shows have been incorporated into stratigraphical summary plots.
Future Services
The improved biostratigraphical understanding will aid companies investigating new prospects and provide a framework for biosteering of deviated boreholes
Deliverables
This study revises and improves stratigraphical understanding of the Namurian and Brigantian sections of a selection of 35 boreholes within northern England and NE Wales This includes the highly prospective Bowland-Hodder and Widmerpool formations. The main stratigraphical tool is quantitative palynology (with innovative counting and analysis techniques, refinements in taxonomy, etc.) which has been tied back to log data and available ammonoid biozones. The selected wells have been complimented by material from type outcrops. Interpreted data summary charts and breakdowns are provided, with logs, lithologies, sedimentology, palynological and palaeoenvironmental data and macrofaunal biozones. Regional correlation panels and maps illustrate basin and sub-basin-scale variations in the depositional systems. The resultant high-resolution biostratigraphy, tied to the chronostratigraphy, provides a framework for all other stratigraphical studies. It will aid future drilling and provide a basis for the biosteering of horizontal wells.
