Shell has said it will proceed with plans to buy the BG Group, its largest-ever acquisition, despite the worsening outlook for energy prices that led the Dutch-based group to write down assets worth nearly $8 billion in the third quarter.

Analysts said CEO Ben Van Beurden was staking his reputation on the deal, which was worth $70 billion when announced in April.

While the purchase will add to Shell’s global natural gas assets, extend its access to oil resources in Brazil and help it replace reserves that have dropped in three of the last four years, critics noted that the 11% slump in oil prices since the takeover was announced are now eroding the foundations of the deal.

When plans to acquire BG were unveiled in April, Shell assumed that oil would rise to $90 by 2018.

For Q3 2015, Shell posted a loss of $7.4 billion, compared with a profit of $4.5 billion in the matching 2014 quarter. Adjusted for inventory changes and one-off items, earnings sank by 70% year-on-year to $1.8 billion.

Shell took write-offs of around $7.9 billion on operations in the quarter, including its recently halted exploration venture off the coast of Alaska and the cancellation of a heavy-oil project in Canada. It also took a $2.3 billion write-down on North American shale gas assets, reflecting downward revision of the long-term outlook for the prices of gas and oil.

In regard to the Canadian project, Van Beurden said the group would halt construction on the 80,000 barrel/d Carmon Creek thermal oil sands project in northern Alberta, due to the lack of infrastructure to move the crude to market. US President Barack Obama up to now has declined to give the green light for the Keystone pipeline designed to transport oil from Canada to the Gulf of Mexico. Prior to his election last week, new Canadian Prime Minister Justin Trudeau had favored the pipeline but has refrained from comment since.

Going forward, the Shell CEO said: “We are making changes to Shell’s portfolio mix by reviewing our longer-term upstream options worldwide, and managing affordability and exposure in the current world of lower oil prices.”