Interesting find... but is this because the "missing barrels" could be acocunted for in other ways?  Inter-European trade or something?  Or could it be export of refined products?  Looks like the capacity of the refinery could easily handle the additional barrels...

Please let me know as I don't have a clue to the answer.

I don't have an answer. I just post the numbers. I just post what I see. I don't know.
The answer is simple.
Russia is beginning to softly co-ordinate its export policy with OPEC.
An official SPR in Russia doesn't exist yet. But you have to take into account the fact that a pipe has a volume. The existing oil pipeline system is the best SPR.
A 1000 km pipe with 1m diameter has a volume of around 5 million barrels. Some abandoned parts of the system (for example the line to Lithuania) could be used to store excessive supply. So, OAO Transneft can fill in its system with marginal oil for a long time. This is so called technical oil.
By reducing the export of oil to the `near abroad' - Lithuania, Belarus and Ukraine - Russia achieves two goals simultaneously: to exert political and economic pressure onto not-fully-loyal countries and to synchronize the export policy with OPEC.
You may be correct. And NO, there is no simple answer. Look at it again. At best you are falling back on a defensive posture. This is bad for your position. You need to fall way back and dig some new trenches. Look at March 1918.