Those look like they go to the ventral side of the aircraft, with multiple tubes. I don't think they're for refuelling, but then again I don't actually know where they exactly refuel on a Flanker.Are those fueling pipes?
If so, it may indicate that a few batch 3 airframes have already flown.
That said if the overall batch 3 J-15 production has been going on for months now then chances are some have already flown.
Given how limited our updates of SAC have been over the years, lots of milestones could have been made without us knowing about it.