Réservoirs complexes: modélisation stochastique et génétique Stochastic and process-based models for heterogeneous reservoirs

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1 Réservoirs complexes: modélisation stochastique et génétique Stochastic and process-based models for heterogeneous reservoirs Jacques RIVOIRARD Equipe Géostatistique Centre de Géosciences 1

2 A common issue Mining, oil, environnement : How to represent the reality of a field, when only a partial information is available? Commonly addressed in geostatistics by: Analyzing spatial variability Using it for possible representations 2

3 Heterogeneous reservoir modeling Creating facies block models from limited information 3

Heterogeneous reservoir modeling A topic developed at

purely stochastic model: Truncated gaussian

meandering reservoirs: FLUMY Truncated gaussian

4 Heterogeneous reservoir modeling A topic developed at MINES-ParisTech since the 80 s Two approaches here: A purely stochastic model: Truncated gaussian simulations A process-based model for channelized meandering reservoirs: FLUMY Truncated gaussian simulation (ISATIS) Scorched view of sand bodies (FLUMY under ISATIS) 4

5 Truncated gaussian simulation 5

6 Truncated gaussian simulation o Striking facts Begins 1986 with IFP Some references Conditional simulation of the geometry of fluvio-deltaic reservoirs (1987) Matheron, G., Beucher, H., de Fouquet, C., Galli, A., Guérillot, D., Ravenne, C. In : Proc., 1987 SPE Annual Technical Conference and Exhibition, Dallas, Texas, September 1987, Reservoir Engineering. p (SPE 16753). Plurigaussian Simulations in Geosciences, 2nd ed (2011) Applications Armstrong, M., Galli A.G., Beucher H., Le Loc'h G., Renard D., Doligez B., Eschard R., and Geffroy F. Springer, Berlin, Germany. Oil : IFPEN, AGIP/ENI, Total, GDF, Petrobras Mining : Areva, Codelco Implementation Isatis, Cobra flow, Landmark, Petrel 6

on the gaussian RF Random Set Proportions depending

7 Truncated gaussian simulation Stationary gaussian random field obeying to a variogram model Threshold on the gaussian RF Random Set Proportions depending on threshold Structure inherited from gaussian field 7

8 Several facies p 2 +p 1 =G (s 1 ) p 1 = G (s 0 ) Threshold s 0 Threshold s 1 Gaussian RF Min. G 1 Max.G 1 Lithotype rule Facies Simulation Use ONE underlying Gaussian RF to simulate several facies 8

9 Three facies Two gaussians Threshold T 1 Gaussian (Y 1 ) Min. Y 1 Max.Y 1 Facies Simulation Max. Y 2 Gaussian (Y 2 ) Min. Y 2 Threshold T 2 9

10 Influence of the lithotype rule Lithotype Rule Y 1 Y 2 10

11 Non Stationarity Stationary Gaussian random field section Constant threshold Variable threshold 11

12 Non Stationarity Constant proportions depth Vertical proportion curve 12

13 Simulations conditional at well data 13

14 Simulations conditional at well data 14

15 Porphyry copper deposit 15

16 Roll-front U deposits Simulation of roll-fronts 3 conditional simulations Non oxidized facies Mineralisation Oxidized facies Courtesy from AREVA 16

17 Extension to oriented facies Simulate roll-fronts honoring the oriented arrangement of the different phases Gaussians: shifted shadowed Flow from left ro right Courtesy from AREVA 17

18 Developments: other extensions Many variants (gaussian components, lithotypes rule) -> identification issue Another family: substitution models (Lantuéjoul 2002) Modeling stromatolithes (carbonates) in progress 18

19 Developments: inference of parameters Automatization in progress (Desassis & Renard, 2013) Variogram of gaussian field from facies indicators Here: one gaussian variable with given proportions 19

20 A stochastic process-based model for channelized meandering reservoirs 20

associated to a meandering system, with applications to fluvial and turbiditic systems Long time scales

21 FLUMY A project developed at MINES ParisTech in the 2000 s Looking for realism in the geometry of sedimentary bodies when modeling heterogeneous reservoirs A model simulating sedimentary processes associated to a meandering system, with applications to fluvial and turbiditic systems Long time scales Rapid simulation Applications Oil (GDF Suez, ENI, EXXON, IFPEN, Petrobras, SHELL) Mining (Areva) Water resource (PIREN Seine) 21

22 Elements of a meandering fluvial system Crevasse splay Deposit Levees Process Overbank flood Levees Shale Paleosols Deposit Overbank shales Process Overbank flood Deposit Crevasse splay Process Levee breach Deposit Point bar Process Migration / Overbank flood NW Deposits Mud-plug / Sand-plug Process migration Levées 22

23 Migration Centerline evolution 1 iteration ~ 1 year ~ 1 annual flood Old Recent 23

24 Overbank floods Aggradation and associated deposits At every OverBank flood : Channel Lag deposit Levee OverBank shales Thickness = Intensity of overbank flood Lateral extension Vertical scale exaggerated! 24

25 Overbank floods Aggradation and associated deposits Due to aggradation during OverBank floods, the channel dominates the floodplain Valley cross-section, resulting from migration and aggradation Point bar Channel Lag deposit OverBank shales Vertical scale exaggerated! 25

26 Levee breach and avulsion «local» avulsion (levee breach within the domain) Crevasse splay New channel path Vertical scale exaggerated! 26

27 Levee breach and avulsion «regional» avulsion (levee breach upstream) Levees Pointbars Abandoned channel 27

28 Lowland deposits (wetlands) Facies below a given reference surface 28

29 A comprehensive model Migration Point bars (yellow) Sand and mudplug (grey and blue green) Overbank flood Channel lag (orange) Levee (dark green) Overbank alluvium (bright green) Levee breaching Crevasse splay I & II, crevasse channels (tan colors) Water table Organic rich deposits (purple) facies 29

Results: contrasted architectures Few floods and avulsions -> developed and connected bodies Geological time: 100 000 itérations = +/- 100

30 Results: contrasted architectures Few floods and avulsions -> developed and connected bodies Geological time: itérations = +/ y Processing time : 3-4 minutes Sand proportion (yellow orange) along vertical Horizontal section z = 4 m 5 m Vertical section W-E 30

Results: contrasted architectures Frequent floods and avulsions -> poorly developed and disconnected sandbodies Geological time: 30 000 itérations =

31 Results: contrasted architectures Frequent floods and avulsions -> poorly developed and disconnected sandbodies Geological time: itérations = +/ y Processing time : 1-2 minutes Sand proportion (yellow orange) along vertical Horizontal section z = 4 m 5 m Vertical section W-E 31

32 Results: contrasted architectures Isolated channels Loranca basin, Spain I. Cojan 32

33 Results: contrasted architectures Amalgamated and eroded pointbars Loranca basin, Spain I. Cojan 33

34 FLUMY FLUMY Software Standalone versions including demo version A structure adapted to plugin and integration in workflows Available under ISATIS FLUMY research project Improvement of the model Decision-making tool 100% conditioning to well data Extension to other environments (turbidites, anastomosed systems ) flumy@geosciences.ensmp.fr 34

Reservoir characterization

1/15 Reservoir characterization This paper gives an overview of the activities in geostatistics for the Petroleum industry in the domain of reservoir characterization. This description has been simplified