#  > Petroleum Industry Zone >  > Reservoir >  >  >  Eclipse Convergence problems

## halim78

Hello,


I'm running a forecast case using Eclipse and I have a lot of convergence problems.
Can any body help me on this issue or give me some books on fixing these problems.

Here is a snapshot of one of the problems:See More: Eclipse Convergence problems

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## temr

There is no book where you can find answers for non-convergence ( as far as i know) in eclipse 
This problems accures when eclipse can not solve the non linear equation - for this ( how its culculates you can find a lot of books here).
But theres is some points you should aware of when building you sim  model which effects the speed of calculations.
1 - cells size and shape - try to take out thin cells form you model
2 -  cells poro and perm - try to avoid rapid changes of perm and perm from cell to cell - less stochastic more deterministic algos for property modeling or use smooth property in petrel
3 - try to not connect different PVT regions
4 - before running the models with wells run the model without wells let say for 5-10 years . After the run upload the sw property and use it as initial Sw  for well run  in this case you will get true equilibrium and you will avoid problems with cross-flows
5 - look for you BHP of you wells , some times run can be stop if eclipse can not eject the history volumes to the cells
6- faults shape - try to make zigzag fault in the sim grid

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## itag

Tem's advice is good.

In many cases the two most common problems are:

a) Low porosity and high permeability cells - these give rise to througput problems. Indentifying and removing these cells ( or lowering the perm there) can help. You need to be able to plot permx vs poro to find these cells.

b) Often too high a vlaue of PERMZ can be a problem. Plotting the histogram of TRANZ or PERMZ and using a MAXVALUE keyword to limit the highest 10% can often improve convergence while not affecting the solutution. ( similarly reducing kv/kh oftne improves convergence - but now the answer will most likley change.

There are many other reasons. I've found these 2 are a good place to start.

itag

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## halim78

Thank you very much for these information.
All these points are Ok in my model, I think the problem  is relative perms curves which have some irregular shape, I'll fix them and see the results.

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## hkazem

Dear Temr,

What would be a solution if there is "cross flow" in the reservoir while initiallizing the simulation model? What parameters you usually check in this case?

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## temr

Hello hkazem.
The solution is quite easy.
Make run for let say 50 years without the wells 
After run export swat from restart file and use it as initial one.
Time machine )))
Read carefully what ve been written above

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## dipak_m

Dear Temr,
Please elaborate in details when I run the model for 50 years without wells and use as a initial saturation to avoid cross flow.

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## vinomarky

The process that temr is illustrating is one where your model (as originally initialized) may not be in equilibrium - consequently from the very start you have fluid wanting to move around without even any well penetrations. By allowing theses fluid movements to fully equilibrate over time and using the resultant (settled) saturation grid as your new initial saturation grid it can remove convergence problems in some cases. 

In my experience though this is only really needed when people try to initialize with scenarios like 'tilted contacts' without incorporating the physical cause of the observation.

Another thing to look at (along the lines of what the guys above point out) is to see if there is consistency in the reported blocks in which the convergence problems are occurring it - it may be as simple as zeroing out a handful of problem cells.

If instead it is indeed down to abrupt changes in your rel perm curves, then you've probably addressed the problem already.

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## dipak_m

thanks

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## temr

It is easy 
in schedule section just put 
Dates 
like
.....

SCHEDULE

dates
1 'MAY' 1988 /
/

dates
1 'JUNE' 1988 /
/

.
.
.
.
dates
1 'JUNE' 2050 /
/

END

Again this method will avoid all possible block crossflows

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## dquento

hello all,
i have encountered a series of problems during a simulation run similar that mentioned in this thread and all related to WELL 3-113. i generated Gas PVT data because it wasn't available. only one PVT region in the model.
_Problem	1/3/1990	4230.000	 UN-PHYSICAL VALUE FOR 1/BG IN PVT TABLE 1 WELL 3-113 PG = 5.0712E+00 RV = 0.0000E+00 1/BG = -4.0867E-01 
Problem	1/4/1990	4261.000	 UN-PHYSICAL VALUE FOR 1/BG IN PVT TABLE 1 WELL 3-113 PG = 3.8311E+00 RV = 0.0000E+00 1/BG = -1.7119E+00_ 
 can someone please explain to me what this means?
thanks, regards.

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## temr

It is mean that during extrapolation of Bg values outside pressure nodes you gave in PVT section eclipse gets negative compressabilities which are non physical 
this usualy happens if BHP of the well drops down dramatically ( 1 bar ) or increases (injectors) 
look for the thread in the forum excell file to check negative compressabilities

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## vinomarky

You are getting negative compressibilities... 1/Bg should always be positive
Is it purely gas model? If so, try extending the defined pressures significantly higher.. I've seen cases where some point cells having numerical convergence issues want to solve to a pressure higher than initialization, which if not covered in your PVT tables can cause the situation you are seeing. 


Plot you 1/Bg's vs pressure and eyeball if they are smooth and continuous - if not, make them.See More: Eclipse Convergence problems

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## halim78

> hello all,
> i have encountered a series of problems during a simulation run similar that mentioned in this thread and all related to WELL 3-113. i generated Gas PVT data because it wasn't available. only one PVT region in the model.
> _Problem	1/3/1990	4230.000	 UN-PHYSICAL VALUE FOR 1/BG IN PVT TABLE 1 WELL 3-113 PG = 5.0712E+00 RV = 0.0000E+00 1/BG = -4.0867E-01 
> Problem	1/4/1990	4261.000	 UN-PHYSICAL VALUE FOR 1/BG IN PVT TABLE 1 WELL 3-113 PG = 3.8311E+00 RV = 0.0000E+00 1/BG = -1.7119E+00_ 
>  can someone please explain to me what this means?
> thanks, regards.



Your gas phase pressure is going down to 3-5 bars, with your Bg table the extrapolated values are negative. 
Why your pressures are very low?

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## FOXNEW

dquento 
Be sure that your PVT table is consistence and the curves are smooth then extend your pressure in the PVT table to include higher values specially if you have Injectors in the model.

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## FOXNEW

halim78,
For the convergence errors you get they guys told you many reasons and it can help and i will add some other points you need to check or try
- Make sure that there are no cells having so small PORO values ( for example put a a porosity cut off, it can be so small values and will not affect the total volume )
- Put a pore volume cutoff to eliminate the small volume cells that will make the model so slow and also it can be the reason for the convergence errors or warnings.
- In the relative perm curves be sure the curves are smooth and put the small values of Kro/krw/krg  (less than 0.005) as zeros.
- The SW array maybe is the main problem of the convergence, so try to use the J-Function to produce your SW array instead of using that one exported from the geomodel or you can use the SW array with the *END POINTS*
 These are some hints but it depends and varies for each model.

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## Shakespear

Try checking your PVT data using this spreadsheet. This is something that our forum friend Ivan Al-Jeboore has.

**[link Point to another website Only the registered members can access]
*link*




<![CDATA[[Only Registered And Activated Users Can See Links]

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## ARLEN

good day for everyone
 Could you help me with issue of convergence
 I build fine grid model which represent matrix block and fracture around. i filled fracture with CO2 and open connection between matrix and fracture to test gravity affect. But when i opened connection there is convergence problem

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## ARLEN

Thank you in advance

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## dipak_m

> Try checking your PVT data using this spreadsheet. This is something that our forum friend Ivan Al-Jeboore has.
> 
> **[link Point to another website Only the registered members can access]
> *link*
> 
> 
> 
> 
> <![CDATA[[Only Registered And Activated Users Can See Links]



Pl upload the file again

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## ARLEN

-- ==================================================  ===
-- Reference Case: Fracturation diffuse tempa rossa
-- CO2 OIL Gravity drainage
-- Created 28/05/2009
-- Projet Carbonate - Ecoulement polyphasique
-- ==================================================  ===

--**********************************************
RUNSPEC
--**********************************************
TITLE
SINGLE POROSITY MONO BLOCK DRAINAGE OF CO2-OIL SYSTEM 

METRIC


---- GRID
DIMENS
--NX    NY    NZ
  28    28    56 /
-- Taille de Bloc 10.0 x 10.0 x 10.0
-- Taille Modle 6.0 x 6.0 x 12.0
-- Modle 1/4 Bloc Matriciel 
-- NB Cell MATRICE : 25 x 25 x 50
-- DIP :  0.0
-- Cellules MATRICE : 1 25   0 25   4 53

NONNC

---- PVT
WATER

COMPS
8 /
EOS
PR /


ENDSCALE
/

TABDIMS
-- NTSFUN   NTPVT   NSSFUN   NPPVT  NTFIP   NRPVT
     2       1       30       66     2        20 /

EQLDIMS
-- NTEQL   NDPRVD    NDRXVD   NTTRVD   NSTRVD
     1       200        10    /

REGDIMS
--- FIPNUM FIPSET	RESNUM	FLUXNUM
2 1 1 2 2* 2 /



WELLDIMS
    2      56      1        2       3     2     1    2 /
-- nwells  ncompl groups  wel/grp etag srtem mixt sepa


--NOSIM

UNIFIN

CO2SOL

UNIFOUT

NSTACK
    150 /

MESSAGES
3* 10000    5* 10000/

START
 1 'JAN' 2000/

GRIDOPTS
1* 2 /

--==================================================
GRID
--==================================================

NOECHO
INCLUDE
'INCLUDE/GRID_Bloc10x10x10_25Cel.Grdecl'/
ECHO


--Property of Fracture
BOX
1 28   1 28   1 56 /
PORO
43904*1 /
PERMX
43904*1e5 /
PERMZ
43904*1e3 /
NTG
43904*1 /
MULTPV
43904*10 /
ACTNUM
43904*1 /
MINPVV
43904*1e-11 /
COPY
   'PERMX'   'PERMY'/
/
ENDBOX 

--Porosity of Matrix
BOX
1 25   1 25   4 53 /
PORO
31250*0.3 /
PERMX
31250*100 /
PERMY
31250*100 /
PERMZ
31250*1 /
NTG
31250*1 /
MULTPV
31250*1 /
31250*1e-11 /
ENDBOX


EQUALS
  OPERNUM  2     1 28   1 28   1 56 / -- HMP 0 Fractures
  OPERNUM  1    	1 25   1 25   4 53 / -- HMP 0 Matrix --> DIFFUSE fracture Kr Fracture
/
MULTREGT
 1 2 0.000001 2* O /
/

INIT

------==================================================  ===========
EDIT
------==================================================  ===========


----==================================================  =============
PROPS
-----==================================================  ============
SGFN 
--Kr gas matrix drainage 
--Sg	Krg dr	Pc o-g 
  0	0	0
  0.1	0.01    0
  0.2	0.04    0
  0.3	0.09    0
  0.4	0.16    0
  0.5	0.25    0
  0.6	0.36    0
  0.7	0.49    0
  0.8	0.64    0
  0.9	0.81    0
  1.0	1.0	0/ -- Edit of max Sg value (set to 1.0) for consistency with Swirr 0.0
  0	0	0 
  0.1	0.1     0
  0.2	0.2     0
  0.3	0.3     0
  0.4	0.4     0
  0.5	0.5     0
  0.6	0.6     0
  0.7	0.7     0
  0.8	0.8     0
  0.9	0.9     0
  1.0	1.0	0/  -- Linear Kr in fractures

SWFN 
--Sw   Krw   Pc w-g dr 
  0	0	0
  0.1	0.01    0
  0.2	0.04    0
  0.3	0.09    0
  0.4	0.16    0
  0.5	0.25    0
  0.6	0.36    0
  0.7	0.49    0
  0.8	0.64    0
  0.9	0.81    0
  1.0	1.0	0/ -- Edit of max Sg value (set to 1.0) for consistency with Swirr 0.0
  0	0	0 
  0.1	0.1     0
  0.2	0.2     0
  0.3	0.3     0
  0.4	0.4     0
  0.5	0.5     0
  0.6	0.6     0
  0.7	0.7     0
  0.8	0.8     0
  0.9	0.9     0
  1.0	1.0	0/  -- Linear Kr in fractures


SOF3
--So  Krow  Krog
  0.0	0.0	0.0
  1.0	1.0	1.0/ -- Edit of last So value (set to 1.0) for consistency with Swirr 0.0
  0.0	0.0	0.0
  1.0	1.0	1.0/

EQUALS
  SWL  0.0     1 28   1 28   1 56 / -- HMP 0 Fractures
  SWL  0.0    1 25   1 25   4 53 / -- HMP 0 Matrix
/
--- Critical Water Saturation
COPY
  SWL SWCR/
/
ADD
 SWCR 0.05  1 25   1 25   5 54	/ -- Matrix
  SWCR 0.05 26 28   1 28   1 56  / -- FRACTURE BACK
  SWCR 0.05 1 28   26 28   1 56  / -- FRACTURE RIGHT
  SWCR 0.05 1 28   1 28   1 3  / -- FRACTURE TOP
  SWCR 0.05 1 28   1 28   54 56  / -- FRACTURE BOTTOM
/

--- Critical Gas Saturation --> trapped gas saturation as no hysteresis
-- Set to 0.2*(1-Swconnate)
COPY
  SWL SGCR 1 28   1 28   1 56 /
/
COPY
 SWL SGU  1 28   1 28   1 56 /
/
MULTIPLY
 SGU -1.0 1 28   1 28   1 56 /
/
ADD
 SGU 1.0  1 28   1 28   1 56 /
/

-- Critical Oil in Water saturation
EQUALS
  SOWCR  0.0     1 28   1 28   1 56 / -- HMP 0 Fractures
--  SOWCR  0.05    1 25   1 25   5 54 / -- HMP 0 MatrixSOWCR
-- Critical Oil in gas saturation
  SOGCR  0.0     1 28   1 28   1 56 / -- HMP 0 Fractures
--  SOGCR  0.01    1 25   1 25   5 54 / -- HMP 0 MatrixSOWCR
/




ROCKOPTS
 2*  'SATNUM' /      -- Rock compressibility table as of SATNUM

ROCK 
 400   9.0E-5 /  -- Matrix compressibility
 400   4.5e-4 /  -- Fractures compressibility (Matrix x5)

------------ PVT COMPOSITIONNEL 8 COMPOSANT -----
-------------------------------------------------
NOECHO

-- Peng-Robinson correction pour les grands facteurs acentriques
PRCORR
-- Standard conditions: T.p (units above)
STCOND
15.0       1.0 /
-- Initial Reservoir Temperature Deg C
RTEMP
85.  /
-- changement des doefficients LBC par default (viscosite) 
LBCCOEF
0.098853  0.051056  -0.014419  0.003933  0.0  /   

-- User/Characterised Components
CNAMES
 CO2  GAZ   GPL   FIOUL  CN1  CN2  CN3  CN4   /
-- Critical temperatures (Deg K)
TCRIT
304.20  229.24  473.54  586.95  663.15  773.150  963.15  1773.15  /
-- Critical pressures (bara)
PCRIT
73.77  47.69  34.22  26.39  20.50  17.50  14.30  6.85  /
-- Critical volumes (m3/mol)
VCRIT
0.0939  0.0924  0.3082  0.4942  0.7563  1.125  1.830  7.000  /
--EQUIVALENT DE VO POUR BEST (m3/mol)
VCOMPACT
0.01966 0.0193467 0.0645309 0.1034757 0.1817 0.2413 0.3697 1.7305 /
-- Acentric factors
ACF
0.2250  0.0453  0.2327  0.3619  0.5500  0.6800  0.8600  0.9000  /
-- Molecular Weights (g/gmole)
MW
44.01  22.09  73.69  118.15  180.82  297.88  550.00  1617.00  /
--tension interfaciale 
PARACHOR
78.  77.  190.0  270.0  500.0  900.0 1300.0  2000.0  /

BIC
 0.00
 0.11  0.11
 0.13  0.016 0.000
 0.12  0.100 0.000 0.000
 0.10  0.110 0.000 0.000 0.00
 0.10  0.120 0.000 0.000 0.00 0.00
 0.10  0.020 0.000 0.000 0.00 0.00 0.00
 /
--DEPTH  CO2    GAZ    GPL       FIOUL     CN1       CN2       CN3       CN4
ZMFVD
3700.  0.000  0.5446  0.0881    0.0822    0.0831    0.1944    0.0065    0.0011
3800.  0.000  0.524   0.089260  0.082102  0.083084  0.201294  0.015441  0.004819
4000.  0.000  0.450   0.093284  0.081765  0.082879  0.226106  0.047614  0.018352
4112.  0.000  0.300   0.126684  0.112023  0.105482  0.245000  0.090000  0.020811
4200.  0.000  0.19998 0.135673  0.118919  0.120539  0.264128  0.112982  0.047779
4300.  0.000  0.100   0.152647  0.133797  0.135620  0.258174  0.127005  0.092757
4400.  0.000  0.100   0.152647  0.133797  0.135620  0.258174  0.127005  0.092757
/  ---Zone PVT1

DENSITY
 1*  1004.  1* /
--oil water gas
-- Water PVT Properties at Pref (Pref Bwref Cw Vis viscosibility=dVw/dP) :
PVTW                                                                      
--  Pref      Bw         Cw            Vw        Cvw
--  BARSA     RM3/SM3    1/BARS        CPOISE    1/BARS
    500.9     1.04       3.72E-05      0.25      5.85007E-05  /
SOLUBILITY
--PRESS  GWR   BW    MUW   CW
 200.    27.  1.055  0.364  4.870E-05  /
------OPTION POUR CO2 Soluble dans L'eau
--RSWVD
--2030.0  0.079393 /
--DEPTH concentrationCO2/H2O




--- QC Kr curves & end-points
EPSDEBUG
-- IX1 IX2 JY1 JY2 KZ1 KZ2 SWITCH
     1    1  1  1   2   2     0/----==================================================  ==============
REGIONS
----==================================================  ==============

EQUALS
  EQLNUM  1     1 28   1 28   1 56 / -- HMP 0 Fractures
  SATNUM  2     1 28   1 28   1 56 / -- HMP 0 Fractures
  SATNUM  1    	1 25   1 25   4 53 / -- HMP 0 Matrix --> DIFFUSE fracture Kr Fracture
  PVTNUM  1     1 28   1 28   1 56 / -- HMP 0 Fractures + MATRIX
/

COPY
	'SATNUM' 'FIPNUM' /
/	

----==================================================  ==============
SOLUTION
-----==================================================  =============

EQUIL
--Datum Pref   W/O   Pcow   G/O   PCgo   Rsvsd   Rvvsd   Acc 
  4106  447  	4175  0  3175  0  0  0  20 1 0  /  -- Matrix 75 m above contact

RPTRST
'BASIC=2'  PRES  SWAT  SGAS  PSAT  RS  VOIL VGAS DENO DENG VISC CONV / --- Report initial state

FIELDSEP
1 20.  1.  /
/
----==================================================  ==============
SUMMARY
-----==================================================  =============
RUNSUM

RGIP    
 /      
ROIP    
 /      
RPR     
 /      
RWSAT   
 /      
ROSAT   
/       
RGSAT  
 /    
ROE
/  

--Date  
ELAPSED 
TCPU    
TCPUTS  
TCPUDAY 
NEWTON  
TIMESTEP

RGFT
1 2/
/

ROFT
1 2/
/
RRPV
/
ROPV
/
BOSAT
1 1 1 /
1 1 28 /
28 28 1 /
28 28 56 /
26 14 3 /
26 15 3 /
26 16 3 /
25 22 3 /
24 22 3 /  
9 21 55 /
/
BOIP
1 1 1 /
1 1 28 /
28 28 1 /
28 28 56 /
26 14 3 /
26 15 3 /
26 16 3 /
25 22 3 /
24 22 3 /  
9 21 55 /
/
BBOIL
1 1 1 /
1 1 28 /
28 28 1 /
28 28 56 /
26 14 3 /
26 15 3 /
26 16 3 /
25 22 3 /
24 22 3 /  
9 21 55 /
/

FCMPR
1 /
FCMPR
2 /
FCMPR
8 /
FXMFG
1 /
FYMFG
1 /
FODN
/
FOPT
/
FGIT
/
FVPR
/
FVIR
/
FODN
/
FGPR
/
FGOR
/
FOE
/

----==================================================  ==============
SCHEDULE
-----==================================================  =============
IMPLICIT

----- WELLS -----------
WELSPECS
 PRODFRAC  FRAC   1 28   4106  OIL    1*  1*  SHUT  /
 INJCO2FR  FRAC   28 1   4106  WATER  1*  1*  SHUT 6* HMIW/
/
-- Well completion specification data:
COMPORD
	PRODFRAC 	INPUT / 
 	INJCO2FR	INPUT /
/ 	
COMPDAT
--Name 			I J K1  K2 	Status Sat CCF diam KHU S  D direc
 PRODFRAC  1 28 1  56 OPEN  1* 	0   0.1  0   0. 1*  Z /

 INJCO2FR  28 1 1  56  OPEN  1* 	0   0.1  0   0. 1*  Z /


 /

WELLSTRE
	PURECO2 1 7*0 /
/			

WINJGAS
--- 	Well		FluidType   FLuidName
		INJCO2FR	STREAM			PURECO2 /
/

-- Control data for production wells:
WCONPROD
--                     Qres     BHPmin
 'PRODFRAC' OPEN RESV  4*  455   50 /
/

WCONINJE
--                          QIres   BHPmax
 'INJCO2FR' GAS OPEN RESV 1*  455  500.0 /
/

TUNING        
--TSINIT TSMAXZ TSMINZ TSMCHP TSFMAX TSFMIN TSFCNV TFDIFF THRUPT
--        
--NEWTMX NEWTMN LITMAX      
  0.001  1      0.0001 0.10   1.2    0.2    0.1 /
 /
  40     1      150 /     
RPTRST
'BASIC=2'  PRES  SOIL  SGAS  PSAT  RS  VOIL VGAS DENO DENG VISC CONV / 


MULTREGT
 1 2 1 /
/
TSTEP
10*0.001 9*0.01 4*0.1 10*1 10*1   /
--------------------------------------------------------- 20.5 DAYS
/
WCONPROD
--                     Qres     BHPmin
 'PRODFRAC' SHUT RESV  4*  455   50 /
/

WCONINJE
--                          QIres   BHPmax
 'INJCO2FR' GAS OPEN RESV 1*  455  500.0 /
/

MULTREGT
 1 2 1 /
/

TSTEP
 5*0.1 8*0.25 10*0.5 4*1 /
--------------------------------------------------------- 3.5 DAYS

WELOPEN
	PRODFRAC SHUT  	 / 
 	INJCO2FR	SHUT  /
/
MULTREGT
 1 2 1000000 /
/
TSTEP
10*0.001 9*0.01 4*0.1  2*0.25 2*0.5 50*1 /
--------------------------------------------------------- 183 DAYS


END
-----------------------------------------------------------------------------------------------------------


Exactly after opening connection it gives convergence problem. i tried to change grid, porosity of matrix, 
 Relative perm are ok as well.  But if i take off connection and put it as 1 from the beginning of injection it is ok! no covergence problem. But when fractures filled with CO2 and matrix with oil initially and openning connection gives this problem

----------


## DAH7542

I tried to run your model but *.grdecl isn't attached (big size maybe).

As Eclipse manual says, "a single cell can cause non-convergence. As we increase the number of cells we increase the odds that a cell will cause non-convergence", however, it seems to me that your problem is not related with the grid itself (based on the fact that once you remove the connection the problem is not there anymore). 

I would suggest that you check the "Maximum Timestep after a well change", i.e TMAXWC or "Maximum length of the next time step following a well modification"; this is item #10 of TUNING keyword which is by default: unlimited for E100 and 20 days for COMPOSITIONAL. You may need to reduce the maximum timestep after a well change.

Best regards.

----------


## ARLEN

i tried but it doest work
 could you run it with grid file which i have attached

----------


## ARLEN

this is Grid comes from PETREL
  try to run it with data file a gave to you ! this is really interesting cuz i have never seen this type of convergence problem
   thx in advance

----------


## trans_I

I am running a carbonate model single porosity single permeability with 775000 cells. My porosity value ranges from 0 to 42 %. Since i don't have permeability values for my model i used a Timur type transform to populate permeability. But the populated permeability is not sufficient to make fluid flow to the wells and a lot more oil rate cut results. As soon as i put some multiplier to the permeability (Global) to make fluid flow across, convergence problem arises and make my model to run very slow (47 hours). I have nearly 100 wells with 10 multilateral and 28 years of history. I am looking for a way out to overcome the problem and make the model run faster.



Moreover when i see my wells, deviation data and perforations in PETREL it seems nice and logical. But after running when i see the SMSPEC in flow viz my wells seem weird/coiled zigzag particularly the multilaterals. Can these be a cause to the problem?

Pl suggest.See More: Eclipse Convergence problems

----------


## DAH7542

Dear trans_I, some observations:

1. Timur's correlation holds for sandstone reservoirs. I wouldn't use it for carbonates. Look for an appropiate correlation for carbonates.
2. Insufficient flow rate with lower than observed water cut might be due to several things, including flow through fracture network (not considered in a single porosity single perm model like yours). If there is indeed flow to high perm (low pore vol) features such as fractures, you will be forced to use large numbers for perm or transmissibility multipliers. 
Are you sure that single porosity single perm model is ok in your case? 
3. As for the convergence problems, I suggest you first identify the source of the problem. To do it, use NEWTON=2 in RPTSCHED. Read carefully the report at each time step while the simulation is still running and identify the problematic cells (those cells with the highest errors). My first impression is that when you increase the global perm by means of the global multiplier the throughput stability condition is not met, this happens when fluid flows throuhg high perm low pore volume cells. If this is the case, you will drastically reduce the run time by increasing MINPV. My suggestion: increase MINPV to the maximum allowable value in your case, run the simulation and compare the run time with the original run.
4. As for the weird trajectories in FloViz, don't worry, this is normal and it's not the cause of your convergence problems. FloViz displays the wells as straight segments between connected cells, that's why you see ziz-zag trajectories. If you want FloViz to display the actual well deviation (as seen in Petrel) you have to load the well deviations by loading the *.dev and *.cnt files into FloViz.

Good luck.

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## trans_I

> Dear trans_I, some observations:
> 
> 1. Timur's correlation holds for sandstone reservoirs. I wouldn't use it for carbonates. Look for an appropiate correlation for carbonates.
> 2. Insufficient flow rate with lower than observed water cut might be due to several things, including flow through fracture network (not considered in a single porosity single perm model like yours). If there is indeed flow to high perm (low pore vol) features such as fractures, you will be forced to use large numbers for perm or transmissibility multipliers. 
> Are you sure that single porosity single perm model is ok in your case? 
> 3. As for the convergence problems, I suggest you first identify the source of the problem. To do it, use NEWTON=2 in RPTSCHED. Read carefully the report at each time step while the simulation is still running and identify the problematic cells (those cells with the highest errors). My first impression is that when you increase the global perm by means of the global multiplier the throughput stability condition is not met, this happens when fluid flows throuhg high perm low pore volume cells. If this is the case, you will drastically reduce the run time by increasing MINPV. My suggestion: increase MINPV to the maximum allowable value in your case, run the simulation and compare the run time with the original run.
> 4. As for the weird trajectories in FloViz, don't worry, this is normal and it's not the cause of your convergence problems. FloViz displays the wells as straight segments between connected cells, that's why you see ziz-zag trajectories. If you want FloViz to display the actual well deviation (as seen in Petrel) you have to load the well deviations by loading the *.dev and *.cnt files into FloViz.
> 
> Good luck.



Thank you very much for the reply DAH7542. I am sorry i did not checked my mail for long. As you mentioned it was throughput related problem only. The NTG in the static model was 0 and 1 only but while up-scalling it gave me a range of NTG starting from 0 to 1. May be that was causing me problem. I put some cut-off value for NTG and increased MINPV also. I used porosity beaning and than populated permeability with some logical transform that finally worked a bit good to my situation.

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## temr

The rule is simple the higher the permeability the more problems you will have. So try to make the perm range in normal way, the perm for card is in the range to 40-60 mD , also try to smooth you perm array to avaid rapid changes in perm

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## saber.sassi

I am looking for these document:

1.G. W. Davies, I. J. A. Gamble, John Heaviside:"Field-Wide Variations in Residual Oil Saturation in a North Sea Sandstone Reservoir" SPE 19851, 1989
2.Land, C.S. "Comparison of Calculated with Experimental Imbibition Relative Permeability." SPE 3360

thank you in advance

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