Eclipse Convergence problems

**vinomarky** · 01-10-2011, 02:35 PM

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.

**halim78** · 01-10-2011, 05:15 PM

Originally Posted by 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.

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?

**FOXNEW** · 01-11-2011, 11:23 AM

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.

**FOXNEW** · 01-11-2011, 11:35 AM

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.

**Shakespear** · 01-11-2011, 11:50 AM

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]

**ARLEN** · 08-25-2011, 06:48 PM

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

**ARLEN** · 08-25-2011, 06:58 PM

Thank you in advance

**dipak_m** · 08-26-2011, 09:57 PM

Originally Posted by 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]

Pl upload the file again

**ARLEN** · 08-26-2011, 10:27 PM

-- ================================================== ===
-- 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 Modèle 6.0 x 6.0 x 12.0
-- Modèle 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** · 08-27-2011, 12:58 AM

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** · 08-27-2011, 01:18 AM

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

**ARLEN** · 08-27-2011, 01:26 AM

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