Basin modelling - data requirements
APT have a number of inhouse databases that are utilised to collect some of this data, while other items are often supplied by the client.
- Location data (well/section/map coordinates).
- Stratigraphic tops data with appropriate depth reference data and information about the depth conversion uncertainty. I.e. well tops, cross-section in depth-domain or depth converted structure maps – (including a seabed or ground elevation surface and, if possible, a Basement surface). Ideally one surface mapped as close as possible to each of the potential source rock horizons identified and the principal reservoir target horizons. Where such surfaces do not exist isochoring up or down from an appropriate surface can quickly generate the required maps.
- Fault outlines.
- Regional cross-sections from seismic and/or literature showing structural and stratigraphic context.
- Lithology data including a lithological description (clay content etc.) by stratigraphic interval, typically generated by mud logs/comp-logs.
- Facies maps to describe the spatial distribution of lithofacies.
- Formation bulk porosity/permeability data.
- Source rock properties including lithology, average total organic carbon (TOC) content, average pyrolysis hydrogen index (HI), kerogen type and kinetic parameters. To fully appraise any potential source rock horizons, processed, environmentally corrected petrophysical logs can be utilised. The principal logs of interest are RHOB, DT, Rt and GR.
Dynamic geometry data and model history
- Absolute ages for intervals, phases of erosion and other processes such as fault opening/closing, salt movement, cementation etc.
- For eroded layers, erosion maps of estimated eroded thickness. Shale velocity data has shown to be useful where uplift is suspected, and thick relatively organically lean, homogenous shale sequences are present.
- Paleo-water depths through time – ideally based upon biostratigraphy.
- Fault timing and properties (sealing or non-sealing).
- Heat flow maps.
- If salt movement is to be modelled, then palaeo-depth maps.
- Present day and palaeo-sediment-water interface temperature (annual average) through time.
- Borehole temperatures, in order of decreasing reliability: drill-stem test temperatures, wireline test data temperatures (RFT, MDT etc.), and bottom-hole temperatures (ideally provided with hole size and time since circulation ceased for correction, otherwise these can be taken as minimum temperatures).
- Optical maturity data, typically vitrinite reflectivity data (%Ro) (preferably including raw data with histograms) but also bitumen or graptolite reflectivity (where appropriate), spore colour index (SCI) or thermal alteration index (TAI) data.
- Tmax Rock-Eval pyrolysis data (requires careful QA/QC).
- Fluid inclusion microthermometry.
- Fission track thermochronology.
- Formation pressure from borehole pressure measurements or wireline log evaluation.
- Porosity and permeability.
- Capillary pressure.
Hydrocarbon accumulation and aquifer data
- Hydrocarbon accumulations with phase, composition, column height, API, GOR.
- Hydrocarbon show locations with compositional data.
- Hydrodynamic information, present day and past.
- Preferred coordinate system (e.g. UTM, spheroid, etc.).
- Study area location and latitude.
- Well location coordinates.
- Culture data, including political borders and physical boundaries (country borders, coastline, block/licence outlines), petroleum system indicators (shows and seeps location, discovery/field outlines) and prospect polygons.
- Regional geology reports and literature, surface geology maps, and Basement geology data (composition/terrane type).
- Potential field data interpreted for basement geology (crustal compositional and thickness).
- Older petroleum systems modelling reports including 1D, 2D and 3D studies.
- Regional geochemical and reservoir studies. Testing and PVT reports or databases, including both pressure-temperature data and fluid physical property data (API, Bo, Bg, P-sat, Dew point etc.).
- New fluid and gas analyses. Depending on what data already exist it is highly likely that new high-resolution biomarker studies and carbon and deuterium isotope analyses of the gases will provide new additional constraints for understanding the temperature and probably age of the source rocks at time of hydrocarbon generation.