Matthew Simons Student

I'm interested in modeling a horizontal well; is it reasonable/possible to do this by selecting the edges in a slice that correspond to the location of the well and assigning them a multilayer well boundary condition, even though it's not passing through layers?

Thanks!

Hello,

I'm modeling the disposal of saline wastewater in a deep, confined aquifer that is 50 m thick. I plan on using an axisymmetric projection and having the disposal well located along the entire length of the left-hand side of the model. I would like to simulate the well using a discrete feature, but am having some difficulty understanding some of the parameters (and how they should be determined given the projection type), specifically Thickness and Hydraulic Aperture (using the Hagen-Poiseuille setting).

Would anyone be able to shed some light on this, or point me towards some resources on the topic?

Thanks

I appreciate the offer, but I don't think it will be necessary to send me the plug-in. I don't think that variations in thermal conductivity will play an important part in my models, but was just curious to see if anything had changed since 2008.

Hi Peter,

I was wondering whether there has been an update to this; is FEFLOW now capable of handling temperature dependence of thermal conductivity? And if not, do you know of a plug-in that may be able to do it?

Thanks!

Hi Peter, thanks for the response.

I see the updated page now, I had been looking at the online help as opposed to the help system incorporated into FEFLOW. The page says that, in density-dependent models, the buoyancy term is considered in the Distributed Source/Sink term of the rate budget. After reading this, I decided to experiment with the Fluid Density options in the Transport Settings tab. I switched from the 3rd option to the first, invoking the Boussinesq approximation, and my imbalance was solved. However, I'm not sure that I'm justified in using this approximation, as my model deals with high density fluids (with solute concentrations on the order of 200,000mg/L, density around 1140kg/m[sup]3[/sup]). I'm having a difficult time finding a source that supplies a numerical range of density gradient over which the Boussinesq approximation is valid, everything I've found so far just says it's valid at low density gradient.

Do you think that I would be justified in using this approximation, or should I find another way to solve my imbalance?

Hello,

I'm trying to run a transient coupled heat and mass transport model and have no problem with convergence, but notice some imbalances in my rate budget. Both heat and mass are fine, with imbalances around 0%, but my fluid imbalance is close to 4%. The majority of this discrepancy is in the Distributed Sink/Source, but I'm having trouble finding information on what this actually means. I did find the following thread in this forum, but don't think the help was ever updated.

http://forum.mikepoweredbydhi.com/index.php?topic=1078.msg2625#msg2625

Could someone please explain what this Distributed Source/Sink is, and how I might be able to go about reducing the fluid imbalance of my model?

Thank you!

I’m interested in axisymmetrically modelling a saltwater disposal well, but am unsure which combination of boundary conditions to use in order to most accurately simulate the well.

For fluid flow, I was planning on using a well BC, with the pumping rate divided by 2*pi as recommended in the online help. However, the help says that in the case of axisymmetric models a specified flux boundary is preferred. What is the reason for this?
For mass transport, I was planning on using mass nodal source BCs on the same nodes that host fluid flow well BCs.

Could someone with experience modelling density-dependent flow provide some insight as to whether these BCs are best suited to this particular problem? And potentially comment on whether the divergence or convective form of the transport equation should be used?

Hello!

I’m creating a model to simulate the disposal of highly saline (TDS on the order of 200,000mg/L) oil field brines in deep aquifers, necessitating the use of a density-dependant model.

I’m trying to better understand the density ratio parameter and how it is used to calculate the density of fluids that fall between maximum solute concentration (Cs) and reference concentration (Co). Does FEFLOW assume that fluid density increases linearly with increasing solute concentration? Or does it have some built-in equation that relates concentration to density, and, if so, where might I find more information on it?