As for remaining oil capacity - according to page 8 of ISO-NE's
21-day energy assessment, we entered the cold spell with roughly 40 million gallons of residual fuel oil and about 50 million gallons of distillate fuel oil on-hand.
Running some numbers:
Number 6 fuel oil (residual fuel oil) has 44.6kwh of thermal energy per gallon. Assuming 40% power plant efficiency, that gets us about 17.84kwh of electrical energy per gallon of fuel oil.
With 40 million gallons, we have about 713,600MWh of electrical energy, which can sustain 7GW of operation for about 102 hours, or about 4 and a quarter days.
Diesel fuel (which is a distillate fuel) has about 40.8kwh thermal energy per gallon, which gets us 16.32kwh of electrical energy per gallon. 50 million gallons gets us about 816,000MWh of electrical energy, which can sustain 7GW of operation for 117 hours, or almost 5 days.
So we have roughly 9 days of fuel stock to burn at current rates, and we've used up 2 of those days, giving us about a week left if gas supplies don't recover, or other sources (solar, wind) don't pick up. Solar will probably pick back up as it will be sunnier, but wind speeds aren't that high next week.