Restauration de bassins sédimentaires avec gocad. J-L. Rudkiewicz, M. Guiton, J-F. Lecomte, I. Moretti, S. Brocheray, M-C.

Transcription

1 Restauration de bassins sédimentaires avec gocad Kine3D J-L. Rudkiewicz, M. Guiton, J-F. Lecomte, I. Moretti, S. Brocheray, M-C. Cacas, (IFP) Février février 2009

2 Summary Principles of geological restoration forward and backward reconstruction Kine3D plugins within Gocad Examples of restorations Limits when using Code-Aster 2

3 Backward restoration Present day at -65 Ma 3

4 Section in the Central Appenines 5 km 4

5 Forward modelling 5

6 Summary Principles of geological restoration Kine3D plugins within Gocad Examples of restorations Limits when using Code-Aster 6

7 Gocad Suite Base Module Seismic Interpretation Velocity Modeling Geologic Interpretation Reservoir Modeling Reservoir Production Drilling Planner 7

8 KINE3D Volumic restoration Kine3D 3: link Code Aster and Gocad Tetrahedra, Hexahedras Final geometry Gocad is used as a mesh generator, visualisation tool and post processing tool 8

9 Principle of 3D restoration The deformation energy of a rock volume is minimized, assuming displacement constraints on some parts Rocks follow linear elasticity Displacement constraints are used to input geological constraints Finite element meshes are used to discretize the equations Code Aster is used to perform computations 9

10 Restoration constraints 10

11 Flattening = in AFFE_CHAR_MECA(... DDL_IMPO=( _F( NOEUD='N1024',DZ=2220.3, ),... 11

12 Fault Lip Closure { } α α + + = + LIAISON_DDL=( _F ( NOEUD=('N777', 'N779' ), DDL=( 'DX', 'DX' ), COEF_MULT=( 1.0, -1 ), COEF_IMPO= , ), 12

13 Fault Gliding Contact AFFE_CHAR_MECA( MODELE= mode_045, CONTACT=( _F( METHODE='CONTINUE', INTEGRATION='GAUSS', ITER_GEOM_MAXI=5, GROUP_MA_MAIT=('R2_5_MA'), GROUP_MA_ESCL=('R2_6_MA'), GLISSIERE='OUI', TOLE_PROJ_EXT=1000, CONTACT_INIT='OUI', ), = 13

14 Preventing Rigid Body Movements with Point Constraints (DDL_IMPO...) DDL_IMPO=( _F( NOEUD='N102',DX=0., ),... 14

15 Pin Faces = = DDL_IMPO=( _F( NOEUD='N102',DX=0., ),... 15

16 Summary Principles of geological restoration Kine3D plugins within Gocad Examples of restorations Limits when using Code-Aster 16

17 Données originales Agha Jari 20 x 16 x 7 km 17

18 Horizons 18

19 Maillages avec 6 grilles 19

20 Restauration des 6 grilles séparément Pin faces in SW and NE sides 20

21 Construction of missing parts 21

22 Putting the missing part in the right position Node contact on visible points Contact on pink fault 22

23 Summary Principles of geological restoration forward and backward reconstruction Kine3D plugins within Gocad Examples of restorations Limits when using Code-Aster the limited size of grids usable the behaviour with various types of COMP_INCR=(_F(RELATION='ELAS', DEFORMATION='GREEN',),), 23

24 Limits on grid sizes on a Linux 32 bits/2mo nx ny nz Noeuds SG Noeuds aster dont Lagrange Equations NOMBRE DE COEFFICIENT S NON NULS DANS LA MATRICE 20x22x6_C0plat x50x6_C0plat x70x6_C0plat x50x12_C0plat x70x15_C0plat

25 Différence de comportement Green élastique Simo_Miehe/VMises_isot_line en élastique Contraintes : jonctions sur la partie jaune contact sur la faille rouge 25

26 Exemple "réel" visé à terme Il reste du chemin à parcourir! 26

27 Restoration with different rheology red grid: homogeneous stiff rheology of sandstone type green grid: soft rheology of shale type in the graben 27

28 Merci 28

29 Output data: dilatancy Local variation of area/volume induced by the restoration Dilatation is zero if one may unfold and close the fault lip without changing the area. Negative dilatation means global extension, positive gobal compression Dilatation is computed on area for surfaces and on volumes for 3D. θ = 29

30 Dilatancy depends upon boundary conditions 30

31 Dilatancy depends upon boundary conditions 31

32 Dilatancy depends upon boundary conditions 32

33 Dilatancy depends upon boundary conditions 33

34 Conclusions Fault sealing: contact to quality control the fault geometry, glide to get access to past past geometry or to define local deformation related to fault geometry Restoration geometry sensible to fault contact conditions not very sensible to rigid rotation preventing conditions not very sensitive to rheology Restoration derived parameters sensitive to rigid rotation preventing conditions sensitive to rheology contrast 34