Russia isn't an official part of OPEC, but pretty much affiliated.

OPEC said we are going to cut supply to boost prices. Russia said fuck that, we are tired of cutting production. You guys (OPEC) cut, but we're going to produce/sell what we damn well please.

Saudis said "aight... bet". So the Saudis/OPEC are going to flood the market to crush Russia's oil industry. Russia probably can't afford to extract oil at these low prices for very long. The Saudis can because it's cheaper to produce there.

So Russia is either going to come to the table begging. Or their oil industry will collapse and the Saudis will take their market share