Hot Oil Circulation

[mokshz]

Hello Friends,

We had suspected some choking in tubing in one of our wells (natural flow), for its liquid rate had droped by 15% over couple of months. THP was 16 KSC, CHP 100 KSC, well perforation at 1850 m, tubing shoe at 1740 m.

So Few days back we carried out 20 m3 condensate circulation (annulus to tubing) with one of our wells and it worked while CHP was maintained at 25 ksc. But when we tried to carry out Hot Oil Circulation we didn't find any flow out of tubing. I am baffled for such a behaviour. Why is that while with condensate we got flow but not with hot oil? And now the well seems to have ceased to flow with CHP 6ksc and THP 0ksc.

Kindly share your views.

Regards,
Mukesh

[ivu]

I am not an expert, but it looks like you've killed the well through annulus.
If both tubing and annulus were communicated, at let´s say 1740m, it looks like that in original flowing situation you had a very light fluid in your annulus compared to that one right now.
You should know were your condensate and Hot Oil have gone. 20 m3 could be the annulus volume for a 7" casing to 4.5" or 5.5" tubing. Inf this is te case, in your first pumping stage you would have only displaced the light annulus fluid to the flowing well, but in the second one you would have injected into the tubing part of the condensate or all of it plus some Hot Oil.
You'd better check densities and volumes of the different fluids. Any dowhole pressure data will be useful.
Note that your THP and CHP dropped so much that you could have some fluid injected into the formation! An echometer of the casing could also give you an indication of any casing liquid level drop.
Try to make sure where you are, before planning the next step and good luck!

[Yengineer]

What are up and against of? Is it wax or asphaltene, or both?
Where are they forming? In reservoir (at and around perforations) or somewhre in tubing?
Do you have any samples?

Cleaning up tubulars with hot condensate is doable but dangerous. You should also be aware of formation sensiitvity.

If wax/asphaltene start forming across perforations, then dump some chemical there (based on sample analysis) and let it soak. Pump it out when is done, do not push it into formation.
If its in the tubing, can be cleaned out as you described. But careful! You are presenting a new fluid in the formation. The more severe the problem is uphole, with more force you are pushing the new fluid into formation. Alternatively you can choose to rum a packer with sliding sleeve in tubing and reverse circulate it clean with a plug in place.