Temperature change in the injection area without heat source using TH2M module in OGS6

Hi all,
I am testing the geostress distribution in the reservoir during cold water injection of the conventional oil production using OGS6’s TH2M module. Since my last post haven’t been replied now, I decided to simplify my model. So I delete the temperature source term which means a heat source in my model to let it degenerate into a HM model since I want to use this as a control to see how temperature affects the stress distribution in the primary fracturing process. As a result, only a pressure source term remains. Here follows my prj code:
test.zip (4.7 KB)

However, when I check the result, I found that the temperature in and around the injection area without a heat source still changes with time, and it seems nonnegligible since the temperature change reaches around 10K after 1h injection like the following picture.

In my opinion, without temperature difference defined by T source term the temperature in the area should keep constant during the process, which is validated from our previous models using THM module. I would like to know if this phenomenon is correct, and if so, how to explain it? If not, what’s the problem? I think it has something to do with phase transition theory, but I’m not sure.
I will appreciate it if anyone could explain my doubts.

Hi, Mr.naumov,
I have updated my results in the following part. As you can see, the cirlce means the injection area in Fig 1. When THM module is applied, The temperature will maintian constant during the injection in Fig.2 (actually there is about 0.001K fluctuation, but I think it is the numerical error caused by my large injection rate 1.192e-2kg/(m2·s)(close to a hydraulic fracturing value), which can be negelected in my opinion). However, when a TH2M module is applied, without the temperatrue source term, we found an obvious temperature drop in the injection area in Fig 3, which I think is an unexpected reult. I have attached pre-processing files for both THM and TH2M mudules, inclucding .geo file, .prj file, .msh file , the needed mesh .vtu file and the final result file. I hope I have provided enough detials for my models.

Fig.1 geometry of the model

Fig.2 result for THM

Fig.3 result for TH2M
test-for-THM.zip (4.1 MB)
test for TH2M.zip (5.6 MB)
By the way, in the model like water injection, which saturation model do you prefer? Right now I use BrooksCorey model but the result is not expected since the water seems not to diffuse far from the injection area and some minus satruation dots apper in the final result. …Maybe I should put more details of the problem in a new post? :thinking:
I hope some useful advice can be provided. Thank you!
Yuhao Liu