I saw reports that Ukraine was warned after the attack on Novorossiysk. Further attacks had the potential to disrupt the oil market. So Ukraine is again forced to defend their country within the limits imposed by third parties whom they depend on for support. So now they attack targets that have few effects outside Russia, like the refineries. Refineries are complex and vulnerable. In the USA, when a refinery is damaged, workers are flown in, and stay onsite for months for repairs. If many refineries are damaged, there might not be enough people with requisite skill to repair them promptly. Western petro companies pulling out has likely already greatly reduced Russia's ability to maintain these plants. Maybe Ukraine should be sending the remaining crews some special treats...
I believe that will happen.
Does ruzzia have sufficient surface-to-air assets to protect the repair workers?
Successful attacks on work-in-progress could have a more detrimental effect than the original attack.