Shell (SHEL.L) on Monday flagged impairment charges of up to $4.5 billion for the fourth quarter, mainly related to the Singapore refining and chemicals hub the oil major is looking to sell.

Ahead of fourth-quarter results on Feb. 1, the company also said gas trading would be significantly higher than the previous three-month period, while oil trading results were expected to be significantly lower over the same period.

Shell's liquefied natural gas (LNG) production volumes were expected to come in at 6.9 million to 7.3 million metric tons, a slightly higher range from its previous guidance. That comes after Shell restarted production late last month at its giant Prelude LNG facility offshore Australia following four months of maintenance.

Shell's upstream production is set to come in at 1.83 to 1.93 million barrels of oil equivalent per day in the fourth quarter.

Meanwhile, its chemicals and products division is expected to post an adjusted earnings loss for the period, it added.

The changes led analysts at Barclays to lower Shell's forecast fourth-quarter adjusted operating result to $5.9 billion, down 11% from their previous estimates.

Shell shares were down by 1.7% at 1242 GMT.

Shell said it would take non-cash, post-tax impairments of $2.5 to $4.5 billion in the quarter.

That includes up to $2.1 billion for the 237,000 barrels per day (bpd) refinery and a 1 million metric ton per year ethylene plant on Singapore's Bukom and Jurong islands, for which it had announced a strategic review last year.