# Local Grid Refinement in T2Well

Hi everyone,

I am using T2Well to model CO2 injection in reservoir system which has two wells; injection well and monitoring well. As far as I understand, in T2Well, wellbore is represented by grid cells that have same cross sectional area of the wellbore (0.2 m in my case). My model is 10 km * 10 km * 1100 m. I am using the grid discretization shown above in which grid size decreases logarithmically towards the injection and monitoring wells. For example, grid size in y-direction decreases from 1831.42 m to 0.2 m at injection well. This grid model results in very long running time (more than 24 hours) and in complete simulation runs. Simulation stops after 0.7 year out of 150 years. I wonder if there is a way to make local grid refinement at the injection and monitoring wells only to avoid such a problem. In the OUTPUT file, I find the following messages indicating that convergence fails because of appearance/disappearance of CO2 at grid cell A5N62 which I think at the boundary of the CO2 plume.

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$$$$$$$$ GAS PHASE DISAPPEARS AT ELEMENT *A5N62* $$$$$ SG = -.767947E-06

...ITERATING... AT [7779, 3] --- DELTEX = 0.165629E+02 MAX. RES. = 0.471262E-02 AT ELEMENT A5I18 EQUATION 3

$$$$$$$$$$$ GAS PHASE EVOLVES AT ELEMENT *A5N62* $$$$$ X3 = 0.246047E-01 XCO2aq = 0.246024E-01 PX = 0.420712E+07 PA

...ITERATING... AT [7779, 4] --- DELTEX = 0.165629E+02 MAX. RES. = 0.382000E-02 AT ELEMENT A5I29 EQUATION 1

$$$$$$$$ GAS PHASE DISAPPEARS AT ELEMENT *A5N62* $$$$$ SG = -.768014E-06

A5I29(7779, 5) ST = 0.669586E+08 DT = 0.165629E+02 DX1= 0.146117E+01 DX2= -.000000E+00 T = 61.250 P = 3115633. S = 0.881892E+00

...ITERATING... AT [7780, 1] --- DELTEX = 0.165629E+02 MAX. RES. = 0.660827E-03 AT ELEMENT A5I29 EQUATION 1

$$$$$$$$$$$ GAS PHASE EVOLVES AT ELEMENT *A5N62* $$$$$ X3 = 0.246048E-01 XCO2aq = 0.246023E-01 PX = 0.420712E+07 PA

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