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Tableau A1.1: Paramètres d’inversion utilisés dans le logiciel RES2DINV. Paramètres d’inversion
Menu Options
1. Change settings
1.1 Inversion Damping
parameters
1.1.1 Damping factors Initial damping factor [enter value between 0.25-0.05] (default: 0.15) 0.15
Minimum damping factor [enter value between 0.01-0.10] (default: 0.03) 0.02
First Layer Damping Factor Use higher damping Factor? [Y / N] yes
i) Higher damping factor value for first layers [enter value
between 1-20] (default: 5) 5
ii) Apply higher damping factors for blocks at sides of model?
[Do not use higher damping factor / Use higher damping
factors]
higher
iii) Adjust damping factors for distances between the blocks in the model ?
[Use uniform damping factors / Adjust damping factors] adjust 1.1.2 Change of damping
factor with depth Manual [enter value between 1.05-1.10] (default 1.05) 1.05
Automatic [Do not use automatic calculation / Use automatic calculation] no 1.1.3 Limit range of model
resistivity [Do not limit resistivity values / Limit resistivity values] do not
i) Upper limit factor [enter value] (default: 50) 50
ii) Lower limit factor [enter value] (default: 0.02) 0.02
iii) [Use average resistivity / Use first iteration resistivity]
averag e 1.1.4 Vertical/Horizontal
flatness filter ratio [enter value between 0.5-2] 1
1.1.5 Reduce variations near
borehole [Yes-reduce variation using distance / No-do not reduce variation] no
i) Damping factor increase to reduce variations [enter a value] (default: 5) 5.00
ii) Rate of damping factor reduction with distance [enter value] (default: 1) 1.00
1.1.6 Use sensitivity values to damp variations near boreholes
[Yes-use sensitivity values / No-do not use sensitivity values] no
i) Damping factor increase to reduce variations [enter a value] (default: 5) 5.00
ii) Rate of damping factor reduction with sensitivity [enter value] (default: 1) 1.00
iii) Cutoff sensitivity values to set higher damping factor [enter value] (default: 0.20) 0.20 1.1.7 Use active constraint
balancing Use active constraints balancing ? [Yes / No] no
i) Select type of active contraints [Normal / Reverse] normal
ii) Lower damping factor [enter value] (default: 0.400) 0.4
iii) Upper damping factor [enter value] (default: 2.500) 2.5
1.1.8 Use diagonal filter Use the diagonal filter components [Y / N] no i) Weight for diagonal filter [enter value between 0.2-5.0] (default: 1.00) 1
103 1.1.9 Use L-Curve method
to select damping factor Use L-curve method ? [Yes / No] no
i) Norm used for L-curve [Always use L2 norm / use same norm (L1)] no
ii) Select the type of model cell to use [Cells with one unit spacing width / Cells with half unit
spacing width] one
iii) Minimum allowed damping factor value [enter value] (default: 0.020) 0.02
iv) Maximum allowed damping factor value [enter value] (default: 0.150) 0.15
v) Select option for damping factor change [ Not allowed to increase / Allowed to increase ]
allowe d 1.1.10 Limit range of data
weights [Do not limit range of weights / Set limits on range weights] do not
i) Lower limit of data weights [enter value between 0.2-0.5] (default: 0.30) 0.30
ii) Upper limit of data weights [enter value between 2.0-5.0] (default: 3.00) 3.00
iii) [Do not set same data weights for different time series / Set same weights for different time
series] do not
1.2 Forward modeling method
settings
Horizontal mesh size [Choose 1 node / Choose 2 node / Choose 4 nodes] 4
Vertical mesh size [Normal mesh / Finer mesh / Finest mesh] finest Type of forward modeling [Finite-difference method / Finite-element method] elemenfinite- t 1.3 Automaticaly adjust grid
size
[Disable automatic grid size / Enable automatic grid size] enable 1.4 Inversion progress settings
1.4.1 Line search local optimization
[Do not use local optimization / Use local
optimization] use
1.4.2 Convergence limit Error change in convergence limit (%) [enter value between 1-10] (default: 5%) 5%
% RMS error for convergence [enter value between 2-5] 0.1
1.4.3 Number of iterations Number of iterations to use [enter value between 5-10] (default: 5) 7 1.4.4 Model resistivity
values check [Check model resistivity for extreme values / Do not check model resistivity for extreme values ] check 1.5 Data/Display
selection
1.5.1 Option for contour
intervals [ Linear / Logarithmic / User defined linear / User defined logarithmic] (default: logarithmic) log 1.5.2 Show pseudosections
during inversion [Yes-Display the sections / No-just show RMS error] yes 1.5.3 Type of gradient array
plot [Use approximate pseudodepth / Use exact pseudodepth] exact
2. Inversion
2.1 Carry out inversion -
2.2 Inversion methods and
settings
2.2.1 Select robust inversion Select type of data inversion constraint [Yes - use robust data constraint / No - use standard data
constraint] yes
i) Robust data constraint cutoff factor [enter value]
(default: 0.0500) 0.05
Select type of model inversion constraint
[Yes - use robust model constraint / No - use standard
model constraint] yes
i) Robust model constraint cutoff factor [enter value]
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Reduce the effect of side blocks on the inversion process ?
[Yes - reduce effect of side blocks / No - do not reduce
effect of side blocks] yes
Limit range of model resistivity values?
[Yes - limit resistivity range / No - do not limit resistivity
range] no
Enable all above options ?
[Yes - limit resistivity range / No - do not limit resistivity
range] no
2.2.2 Modifiy smoothness- constrained least-squared method
[Yes - Use smoothness constraint model resisitivity values as well / No - Apply smoothness constraint
only on model change vector] yes
[Yes - Include damped least-squares constraint / No - Use smoothness-constraint only] no 2.2.3 Choose logarithm of
apparent resistivity [Use logarithm of apparent resistivity / Use apparent resistivity] log 2.2.4 Type of method to
solve least-squares equation [Use standard Gauss-Newton / Use incomplete Gauss-Newton]
standa rd i) Convergence limit for the incomplete Gauss-Newton method [enter value between 0.005-0.02]
(default: 0.0050) 0.005
ii) Use scaling for incomplete Gauss-Newton method [No - do not use scaling / Yes - use scaling] yes 2.2.5 Use reference model
in inversion [Yes - use reference model / No - do not use a reference model] yes i) Reference model damping factor [enter value between 0.05-1.0] (default: 0.010) 0.01 ii) [Use default resistivity value / Use user defined reference value] default j) User defined reference resistivity value [enter value] (default: 100.0) 100
2.2.6 Fast inversion of long survey lines or large data sets
Use optimized Jacobian algorithm ? [Yes - use optimized Jacobian calculation / No - use
normal calculation algorithm] no
Use fast calculation of Jacobian matrix ?
[Yes - use fast approximate method / No - use standard
exact method] yes
Use sparse inversion technique ?
[Yes - use sparse inversion method / No - use standard
method] no
i) Number of electrodes in each segment [enter a
value between 200-600] 250
ii) [Yes - use 1 mesh node / No - use at least 2 nodes] no 2.2.7 Use fast jacobian
routines for dense data sets
[No - Use standard routines / Yes - use fast Jacobian routines]
no
2.2.8 Set time-lapse
inversion settings Time lapse damping factor [enter value between 0.5-5.0] (default:0.25) 0.25
[No constraints / Smooth changes / Blocky changes] (default: smooth changes) blocky
Reduce time-lapse damping factor with
each iteration? [No - do not reduce / Yes - reduce] yes 2.2.9 Select method to
handle missing data points [Implicit method / Explicit method] implicit
2.2.10 Floating electrodes survey inversion method -
2.2.11 Limit water extent for underwater electrodes survey no
2.3 Model discretization
2.3.1 Display model blocks -
2.3.2 Change thickness of layers
Ratio of first layer thickness to the unit
electrode spacing [enter value] (default: 0.5) 0.5
Rate at which the layer thickness
increases with depth [enter value between 1.05-1.15] (default: 1.10) 1.1
Allow number of model parameters to
exceed number of data points? [Yes / No] yes
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2.3.3 Modify depth to layers -
2.3.4 Use extended model Use extended model? [Yes / No] no
2.3.5 Use model with block
of the same widths [All model blocks have equal widths / Model blocks need not have equal width]
all equal [Yes - use cells of approximately equal width / No - use the default arrangement] no
2.3.6 Reduce the effect of
side blocks Reduce the effect of the side blocks ? [None / Slight / Severe / Very severe] Make sure all blocks have equal widths?
[Yes - use blocks with same widths / No use default
arrangement] same width 2.3.7 Change width of blocks
Select width of model block (1 is the nomal width) [1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10 / 11 / 12 / 13 / 14
/ 15] -
2.3.8 Use model refinement
[Use normal model cells with widths of one unit spacing / Use model cells with widths oh half the unit
spacing] normal
2.3.9 Set left and right limits
of model Model left limit [enter value] -
Model right limit [enter value] -
Do you want to use the above model
limits? [No - use default limits / Yes - use above limits] -
2.3.10 Type of cross-
borehole model [Standard model / Model with smaller blocks] -
2.4 Model sensitivity options
2.4.1 Display model blocks sensitivity selecte d 2.4.2 Display subsurface sensitivity - 2.4.3 Normalize sensitivity values - 2.4.4 Generate model blocks - 2.4.5 Calculate resolution for homogeneous model
-
2.4.6 Calculate model resolution for inversion model
[Yes - calculate / No - do not calculate]
yes
2.5 I.P. Options
2.5.1 I.P. data and model weights -
2.5.2 Cutoff for valid I.P. values -
2.5.3 Change range of model I.P. values -
2.5.4 Select type of I.P. model transformation -
2.5.5 Use I.P. model refinement -
2.5.6 Type of I.P. smoothness constraint -
2.5.7 Joint or separate IP inversion -
3 Topography Options 3.1 Display topography
-
3.2 Select type of trend
removal [Average elevation / Least-squares straight line / End-to-end straight line]
averag e 3.3 Type of topographic
modeling
[No topographic modeling, ie. Ignore the topography / Distorted finite-element grid with uniform
distortion /
Distorted finite-element grid with damped distortion / S-C transformation with distorted finite- element grid]
unifor m distorti
on i) Topography distortion damping factor
[enter value between 0.1-2.0]
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