1. Fast, interactive hydrocarbon systems modelling

2. Why? – The point of a geometric approach Focuses on first order effects Fast to run Easy to change Easy to communicate The ability to easily, and above all rapidly, integrate structural and sedimentological effects, regional and local effects into a first order model allows the many more scenarios to be assessed. This means greater confidence in the scenario you choose.

3. What can geometric modelling reveal? viability of sediment access location of depocenters potential to locate occurrence of fault seal issues potential accumulation number, size and location correlation with known data prospect sensitivity to multiple factors, e.g. timing of events, isostatic effects, facies distribution

4. Workflow change model, e.g. geometry, attributes build model populate the model with attributes restore the model map at deposition time forward model map at charge time sensitivity testing

5. Workflow – model building horizons and faults in a tidy model cultural data included, e.g. existing fields seismic attributes integrated facies maps integrated erosion rebuilt palaeobathymetric data included The model can be refined during restoration

6. Workflow – populating with attributes can be derived from many sources can be added from spreadsheets can be edited by hand or ‘painted’ onto surface can vary laterally and between layers

7. Workflow – Backstripping Initial model Top layer removed, model isostatically adjusted

8. Workflow – Backstrip Further backstripping and isostatic adjustement to deposition time

9. Workflow – Analyse for deposition Sediment depocenters mapped and ‘filled’ to desired level. Sand body shape and location integrated into model

10. Workflow – Analyse for charge Hydrocarbon migration paths shown in white for reservoir facies. Sand bodies mapped as facies attributes on surface, (warm colours = sand-prone).

11. Workflow – Sensitivity testing impact of isostatic adjustment Accumulations are large and simple in shape Accumulations are much smaller! Without isostatic adjustmentWith isostatic adjustment

12. Example 1 – Salt

13. Isolated sediment packages Sediment spill thickness 500ft

14. Example 1 – Salt Partially merged sediment packages Sediment spill thickness 1000ft Note: increased size of individual catchment areas

15. Example 1 – Salt Fully merged sediment packages Sediment spill thickness 1500ft Note: increased size of individual catchment areas

16. Example 1 – Salt Up-dip hydro- carbon migration routes (T2) related to sediment spill planes (T5) Prospects Pull-up artefact below isolated salt

17. Sediment accumulations oil migration routes Example 1 – Salt

18. Benefits – focussed technical effort Location of potential reservoir bodies can be mapped and high risk areas discarded Coincidence of high potential for reservoir presence can be matched with high charge potential Example 1 – Salt This can be done before any detailed facies analysis, thermal history analysis etc needs to be done.

19. Depositional surface Example 2 – Reservoir presence present daydepositional time

20. Prospect area showing; known sand pinchout modeled sand pinchout seismic attribute limits Example 2 – Reservoir presence

21. With modelled compacted sediment fill Example 2 – Reservoir presence field prospect

22. Example 2 – Charge risk Northern producing fields Prospect has no charge potential as kitchen is too far to west Prospect is super drainage cell for the region at >120m fill

23. Example 2 – Charge risk Northern producing fields Prospect with charge and culminations Prospect is super drainage cell for the region

24. Example 2 – Charge risk Model Both the Base Lower Cretaceous and Balder horizons. Base Lower Cretaceous conditioned to Jurassic sub crop line Balder conditioned to sand pinch out Jurassic Balder BCU

25. Example 2 – Charge risk Northern producing fields receive charge Prospect – super drainage cell for the region relying on spill from northern producing fields Charge from the south bypasses upper reservoir

26. Benefits – prospect viability Sediment model assessed for viability Multiple charge scenarios assessed for their impact on the charge potential This allows a variety of charge paths and times to be considered before assessing the likely charge risk on the prospect. It also allows better definition of more detailed reservoir/thermal models in the event of successfully locating an accumulation. Example 2 – Reservoir presence/Charge risk

27. Example 3 – Evolution of deposition Model has been decompacted and backstripped Sediment was sourced from north Depth map of depositional surface, blue = deep

28. Example 3 – Evolution of deposition Red = earliest stage deposition Blue = latest stage deposition Seismic amplitude map

29. Example 3 – Evolution of deposition 450m depositional fill Main depocenter occupies south west corner of model Correlates with red amplitude values Unconnected depocenter to the north Correlates with red amplitude values.

30. Example 3 – Evolution of deposition 460m depositional fill Main depocenter has extended to the north and slightly to the east. Partially matched by grey amplitude values

31. Example 3 – Evolution of deposition 470m depositional fill Depocenters merge across the southern area, extending to the east. Correlates with the grey amplitude values

32. Example 3 – Evolution of deposition 480m depositional fill Final geometry of depocenters shows a poorer correlation with the amplitude pick.

33. Composite map of deposystem edge Example 3 – Evolution of deposition Eastwards migration of the depositional system Supporting the interpretation made for the amplitude map. Northern depocenter has remained unchanged

34. Benefits - early stage prospect assessment and risk factor identification Rapid test of evolution of depositional fill provided confirmatory evidence for initial premise Sequential fill in 10m increments of uncompacted fill demonstrates the extreme sensitivity of prospect shape to depositional thickness. This allows early stage support for prospect validity plus highlighting the potential risk areas for further study Example 3 – Evolution of deposition

35. Fast, easy Concept validity testing Early prospect evaluation support Multiple scenario testing Identification of relevant sensitivity factors Larger database for detailed model building Conclusions - Benefits of geometric dispersal/migration testing

36. The author would like to thank colleagues at Midland Valley for discussions and recommendations. Midland Valley would like to thank bp for the permission to use some of the models which appear in this presentation. The functionality presented here was developed in association with bp. Acknowledgements