The first reports were not sure of the extent of the damage and suggested not much impact on oil prices as there is currently a surplus, however, later reports indicate an expected significant fall in production (although no time frame is given). I wonder if we will ever get the story of just how bad it is, or if we will have to use the export numbers as a proxy to estimate the damage.
An analysis opinion posted on BBC states
The Khurais oilfield produces about 1% of the world's oil, and Abqaiq is the company's largest facility - with the capacity to process 7% of the global supply. Even a brief or partial disruption could affect the company, and the oil supply, given their size.
There was a sharp intake of breath as analysts I spoke to today digested the information that reports suggest that half of Saudi Arabia's oil production could have been knocked offline by these attacks.
The country produces 10% of the world's crude oil. Cutting this in half could have a significant effect on the oil price come Monday when markets open.
It also could impact on the (long delayed) IPO
The success of the drone strike shows the vulnerability of Aramco's infrastructure, at a time when it is trying to show itself in its best light while gearing up to float on the stock market.
https://www.bbc.com/news/world-middle-east-49705197
I suppose that this attack would benefit every other producer country.