Detailed Core Description
Badley Ashton provides precise core observations and validated interpretations via detailed interpretative graphical core descriptions including lithotype analysis, the identification of sedimentological features as well as pore types, cementation, visual estimations of reservoir quality and the recognition of key surfaces, stacking patterns and depositional hierarchy. Generation of user friendly geological well summary panels, integrated diagrams and development of depositional models provides clear explanation and understanding of the sedimentological building blocks required for static modelling. The integration of all sedimentological and petrographic data aids reservoir characterisation and prediction. The core description of clastic reservoirs is undertaken at a detailed 1:50 or 1:20 scale and includes a graphical illustration to reflect the core in terms of its grain size, physical sedimentary structures and other features (eg. high-angle cross bedding, current or wave ripples and mudclasts). Deformation structures (eg. slumping or load structures) and ichnofabrics (including burrow intensity and diversity) are also recorded so as to build up a picture of the depositional processes.
Calibration with Wireline Logs and a Framework for Reservoir Quality Analysis
The cored interval is calibrated with the wireline logs and, whenever possible, image data and characterised in terms of its lithological make-up, bed/bedset-scale descriptive depositional packages and their stacking pattern, that are reproducible at a wireline log resolution scale. The lithotype and depositional package schemes will be used to develop interpretative genetic elements that provide basic geometric information with unique sedimentological/lithological properties.
The core and log facies interpretations will be evaluated together with BHI data (if available) to assess the vertical evolution of the study interval and to characterise the depositional model, including an appraisal of palaeotransport direction(s) where appropriate. In multi-well studies interpretations from each well will be cross-referenced against all previous and ongoing studies, including an assessment of lateral facies variations. Any uncertainties and alternative interpretations will be highlighted wherever appropriate.
These data provide the framework within which reservoir quality analysis is undertaken, together with the visually coded core analysis data. The petrographical/reservoir quality data, including any CCA data and/or SCAL data will be coded by the sedimentological descriptors and specific parameters (grain size etc). The integrated sedimentological and petrographical data will then be used to assess the mineralogical/textural composition, the paragenesis and controls on reservoir quality within and between the different descriptors and reservoir layers, and importantly, between wells.
Interpretation of Reservoir Architecture
Following a full integration of all sedimentological, structural, petrographical and reservoir quality data, interpretation of the reservoir architecture can be undertaken. This may be purely based on core data, calibrated against wireline logs, or may include well test/production data (eg. MDT/PLT) and SCAL data (depending on the technical focus).
The aim will be to highlight potential sandbody geometries/scales, flow units, baffles/barriers and internal heterogeneities, with integrated petrographical analyses highlighting the controls on net reservoir (eg. within coarse- grained or weakly cemented intervals). The possible development of baffles or barriers within the study interval and/or any heavily cemented units (from the the lithotype to the reservoir layer-scale) will also be assessed. Appraisal of the reservoir architecture may also assess the timing of hydrocarbon charge and diagenesis (through fluid inclusion analyses), bitumen distribution and also any resultant implications for reservoir development, including possible formation damage issues (eg. fines migration or the presence of swelling clays).
This high resolution A3 poster provides an overview of the techniques that we use in the characterisation of Clastic reservoirs. (5.8mb)
The following case studies may be of interest:
- Reservoir quality analyses and prediction - Zubair Formation, Kuwait
- Greater Burgan Field: defining the Wara Formation reservoir architecture
- BHI Differentiation of types of fluvial system: Triassic, Ourhoud Field
- The application of Borehole Imaging in appraising a Triassic (TAGI) fluvial reservoir,
- Sedimentology and depositional setting of the Asl and Hawara Members, October Field, Egypt
The following articles may be of interest:
- Sedimentology of Paralic Reservoirs: Recent Advances - Geological Society SP 444 available Online First
- Geological Society of London: Deep-water Depositional Systems: Advances and Applications
- 8th Petroleum Geology of NW Europe Conference
- Badley Ashton Field Trip for KOC staff
- Badley Ashton Presentation at the 2016 William Smith Meeting
The following publications may be of interest:
- An integrated description of the stratigraphy and depositional environment of the “Main Pay” member of the Zubair Formation, Rumaila, Iraq
- A sedimentological and diagenetic description of the Carboniferous section in RKF Field, Berkine Basin, Algeria
- Advance and retreat of the Brent delta: recent contributions to the depositional model
- Integrated Reservoir Description of the Ugnu Heavy-oil Accumulation, North Slope, Alaska
- Stratigraphy and structure of Devonian fluvial sediments, western Beara Peninsula, south-west Ireland