The British oil-and-gas giant said the non-cash, post-tax charges are attributable across its business divisions.

BP (NYSE:BP) -1.3% pre-market Tuesday after saying Q4 results will be hurt by lower oil and gas production, refining margins and trading, while also delaying its investor day due to a planned medical procedure by CEO Murray Auchincloss.

BP said on Tuesday that lower refining margins would hurt its fourth-quarter profit by $100 million to $300 million and that it expects oil trading to be weak.

BP forecasts that weaker realized refining margins will dent the Q4 earnings by up to $300 million. Refinery turnaround activity is also set to have a higher impact for the fourth quarter compared to the third quarter.

KEY TAKEAWAYS BP stock is falling in premarket trading Tuesday after the British oil giant said it expects to book impairments of between $1.0 billion to $2.0 billion in the fourth quarter.BP also forecast "weaker" fourth-quarter refining margins.