1. Their current production capacity in Russia will decline, since they won’t be able to receive new equipment and spare parts.
2. Their exports capacity may be reduced if more sanctions will come.
3. Their cashflow will be heavily impacted by sanctions. They may not be able to receive money or spend them on domestic market (eg pay salaries).
4. Their foreign investments may be frozen or they may be forced to sell.
It is heart-breaking to hear that we exclude energy from the embargo fighting to keep the gas prices low at all costs. We should pay $10 per gallon at the pump. And work at curbing our gas consumption.
Edit: note that I have no idea of the value myself. I'm just saying that if you were to accept BP's view, then they're not necessarily giving Russia a gift of any kind.
Putin's counter-sanctions have created an environment where the PR benefit of publicly rejecting their Russian assets is worth more than the value of the assets themselves.
Weird world we live in.