Search and Discovery Article #41506 (2014)** Posted December 29, 2014

Transcription

1 Improved Resolution of a Subtle Stratigraphic Play in a Mature Basin: Integration of Traditional Geological Techniques and Seismic Geo-modelling Technology* Siddharth Mukund 1, Ingelise Schmidt 1, and David Alan Stanbrook 2 Search and Discovery Article #41506 (2014)** Posted December 29, 2014 *Adapted from oral presentation given at AAPG International Conference & Exhibition, Istanbul, Turkey, September 14-17, 2014 **Datapages 2014 Serial rights given by author. For all other rights contact author directly. 1 Maersk Olie Og Gas AS, Copenhagen, Denmark (siddharth.mukund@maerskoil.com) 2 Maersk Oil and Gas, Aberdeen, U.K. Abstract Exploration for hydrocarbons in mature basins is increasingly challenging and potential prospects have a greater degree of complexity and uncertainty associated with them, compared to historical finds. The case study area has been explored for hydrocarbons for more than 25 years during which time there has been a notable degree of success in drilling reservoirs in structural closures. As a result, there is a need to explore for the difficult hydrocarbons, which are possibly sitting in stratigraphic traps and other complex settings unlike conventional structural traps. A potentially large turbidite system was identified from seismic data using conventional interpretation methods and attribute extractions that proved to be seismically anomalous. Regional well-based geological work established gross depositional environments across the region that indicated a sand prone provenance area to the north of the area of interest. However, the geological context of these isolated sand deposits has been limited due to the uncertainty associated with the seismic interpretation in a structurally complex geological setting. Conventional interpretation techniques limit the ability to interpret and analyze these stratigraphic levels of interest across an inversion structure to an inferred sand provenance area. In this paper, we demonstrate and evaluate the possibility of discovering more subtle hydrocarbon reservoirs within the prospective interval of interest, using an integrated interpretation strategy exploiting geological and geophysical data and using innovative interpretation approaches. An innovative geo-modeling technology has been exploited to develop a methodology that helps to reduce the uncertainty of the seismic interpretation process and improves our understanding of the stratigraphy. In addition, data from seismic inversion was also integrated for interpretation purposes. The approach to interpretation demonstrated in this paper has helped to impose strong constraints to

2 guide the seismic interpretation and reduce uncertainty. The techniques used to construct a reliable geo-model eventually made it possible to correlate horizons across the inversion structure, which revealed amplitude anomalies suggesting a channel system across a shelf area down to the anomalies in the deeper basin thereby completing the geological model.

3 Siddharth Mukund, Ingelise Schmidt, David Alan Stanbrook Maersk Oil & Gas Improved Resolution of a Subtle Stratigraphic Play in a Mature Basin: Integration of Traditional Geological Techniques and Seismic Geo-modelling Technology

4 The Agenda Background Early Seismic Interpretation The Challenge Geo-modeling Technology 3D Geo-model QC & Constraints Geo-model Constraint using Seismic Inversion Seismic Attribute Interpretation using High Density Geo-Model Horizons Conclusions

5 The Agenda Background Early Seismic Interpretation The Challenge Geo-modeling Technology 3D Geo-model QC & Constraints Geo-model Constraint using Seismic Inversion Seismic Attribute Interpretation using High Density Geo-Model Horizons Conclusions

6 Early Work RMS Amplitude Well-1 Erosional Base Top Channel Well-2

7 WEU DEPOSrTlONAL ENYfiONMENT 0 Lower Shoreface I T ran5ilion ON1cn I Shelfal 0 Mame, hfftor Tem!Strial lnput 0 Mame, Major Tem!Strial lnput """... Resttic:Ied Mame x x ""'... x Not Known I Uncef1afl / lkld i~ted Mssng Sedion EfMRONMENT OF DEPOSITION Lower Shon!fiIce. to ~ MarM, MmorTem!S1riaIinput ' / T"""""" ~... // """...,. ttisng secmn Xx. x. X DEPOSITIONAL BOUNDARY -- Known ---- ElOSiv~ 1 Non-deposiiion x - - lnf~rted Speeulativ~ Upper Interval x X

8 WEU DEPOSrTlONAL ENYfiONMENT 0 Lower Shoreface I T ran5ilion ON1cn I Shelfal 0 Mame, hfftor Tem!Strial lnput 0 Mame, Major Tem!Strial lnput """... Resttic:Ied Mame x x ""'... x Not Known I Uncef1afl / lkld i~ted Mssng Sedion EfMRONMENT OF DEPOSITION Lower Shon!fiIce. to ~ MarM, MmorTem!S1riaIinput ' / T"""""" ~... // """...,. ttisng secmn DEPOSITIONAL BOUNDARY -- Known ---- ElOSiv~ 1 Non-deposiiion - - lnf~rted Speeulativ~ Lower Interval

9 The Agenda Background Early Seismic Interpretation The Challenge Geo-modeling Technology 3D Geo-model QC & Constraints Geo-model Constraint using Seismic Inversion Seismic Attribute Interpretation using High Density Geo-Model Horizons Conclusions

10 Depositional Environment Sand Provenance Area Upper Int Lower Int Prospect Outline

11 Conventional Seismic Interpretation Upper Interval High Vertical Exaggeration

12 The Agenda Background Early Seismic Interpretation The Challenge Geo-modeling Technology 3D Geo-model QC & Constraints Geo-model Constraint using Seismic Inversion Seismic Attribute Interpretation using High Density Geo-Model Horizons Conclusions

13 Geomodelling Technology Seismic GeoModel Thickness Attribute Thickness Attribute Extracted to surface

14 Geomodelling Technology Workflow Raw Interpretation Model Geo-Model with Manual Interpretation QC of 3D Geo-model using Attribute Stacks Generation of 3D Geo-model & Horizon Stacks Seismic Attributes mapped to Horizon Stacks e.g. Thickness

15 The Agenda Background Early Seismic Interpretation The Challenge Geo-modeling Technology 3D Geo-model QC using Thickness Attribute Geo-model Constraint using Seismic Inversion Seismic Attribute Interpretation using High Density Geo-Model Horizons Conclusions

16 Geo-model QC using Thickness Attribute Geo-model Horizon

17 Geo-model QC using Thickness Attribute Geo-model after Geo-model Horizon Initial Geo-model Additional Constraint Constraint

18 Geo-model QC using Thickness Attribute "','.,,.' :... '\... '.-. ':-;:'1 " ~.. ~~ ~. ": ' ~ :...' Thickness Attribute Map - Before Thickness Attribute Map After

19 Geologic Expression of Thickness Attribute N S Geo-model with Conceptual Fault Plane Thickness Attribute Map

20 The Agenda Background Early Seismic Interpretation The Challenge Geo-modeling Technology 3D Geo-model QC using Thickness Attribute Geo-model Constraint using Seismic Inversion Seismic Attribute Interpretation using High Density Geo-Model Horizons Conclusions

21 Geo-model Constraint using Seismic Inversion N S Horizon Interpreted using RAI Volume

22 Geo-model Constraint using Seismic Inversion N S

23 The Agenda Background Early Seismic Interpretation The Challenge Geo-modeling Technology 3D Geo-model QC using Thickness Attribute Geo-model Constraint using Seismic Inversion Seismic Attribute Interpretation using High Density Geo-Model Horizons Conclusions

24 Basin Evolution from Attribute Stack Isochore Map Envelope Attribute ~. "'- --

25 Basin Evolution from Attribute Stack Isochore Map Envelope Attribute

26 Basin Evolution from Attribute Stack Isochore Map Envelope Attribute

27 Basin Evolution from Attribute Stack Isochore Map Envelope Attribute \."- ~.,

28 Basin Evolution from Attribute Stack Isochore Map Envelope Attribute Lower Interval Horizon Lower Interval Horizon

29 Basin Evolution from Attribute Stack Isochore Map Envelope Attribute

30 Basin Evolution from Attribute Stack Isochore Map Envelope Attribute

31 Basin Evolution from Attribute Stack Isochore Map Envelope Attribute

32 Basin Evolution from Attribute Stack Isochore Map Envelope Attribute / Upper Interval Horizon Upper Interval Horizon

33 Seismic Attribute Maps from Final Geo-Model Feeder Channel Expression Approximate Width 1 Km Region across the Inversion Structure No Prior Interpretation

34 Geo-model Constraint using Seismic Inversion SW NE PaleoScan amplitude Channel axis High vertical exaggeration NW SE Paleo shelf Paleo basin Later inversion High vertical exaggeration

35 The Agenda Background Early Seismic Interpretation The Challenge Geo-modeling Technology 3D Geo-model QC using Thickness Attribute Geo-model Constraint using Seismic Inversion Seismic Attribute Interpretation using High Density Geo-Model Horizons Conclusions

36 Conclusions Seismic attribute expressions revealed anomalies resembling turbidite deposits; Difficulties with seismic interpretation limited the geological understanding Conventional interpretation techniques alone were insufficient to improve our understanding of the depositional system Geomodeling technology allows for an innovative way to study and interpret seismic volumes; providing the opportunity to generate a high density of horizons Seismic attributes and Geomodeling technology together allow to constrain the seismic interpretation and reduce the associated uncertainty Basin evolution and depositional model established from sedimentological study was supported through stratigraphic slicing of the thickness attribute The study helped to link the observed amplitude anomalies to the sediment source on the seismic data with expression of feeder channels The integrated approach combining new technology with elastic inversion and conventional sedimentological studies has helped significantly in de-risking this new play

37 Thank You