The number of years of production left in Royal Dutch Shell's oil and gas reserves fell for the sixth year in a row in 2019 to below eight.
 
But there was little reaction from investors to the steady decline in what was once considered a key metric for gauging the strength of the world's major oil and gas companies.
 
There is a growing perception the world holds enough oil and gas to meet demand many times over, especially against the backdrop of a gradual shift away from fossil fuels because of concerns about climate change.
 
"The days of companies having 15 years of reserves have largely gone," said Redburn analyst Stuart Joyner. "With the energy transition you would expect reserve life to come down."
 
Shell was rocked in 2003 when it revealed it had inflated its oil and gas reserves for years, leading to the sacking of its chairman and chief financial officer.
 
The company's so-called reserve life last increased in 2013 to just below 12 years but it has been on a downward trend ever since and hit 7.9 years in 2019.
 
The reserve life of several of the world's biggest oil and gas companies, including BP and Total, has dropped in recent years but Shell's is now significantly below the industry average in 2018 of about 11 years.
 
Investors closely monitored oil and gas companies' reserves for decades, especially during the rapid growth in Chinese demand from the turn of the century.
 
But after the 2014 oil price crash, the focus shifted to companies' profitability, leading many to sell assets to raise capital, which in turn led to a decline in reserves.
 
Shell Chief Executive Officer Ben van Beurden told analysts on Thursday that the decline in reserve life, "doesn't represent the truly integrated and diverse portfolio we have or our focus of value over volume".
 
The low reserve ratio could nevertheless prove to be a problem for Shell as it is seeking to sell more oil and gas assets to lower its debt burden and pay for a $25 billion share buyback programme, Joyner said.
 
To partly offset any concerns over the decline, Shell plans to tap third-party reserves from developments such as Canada's giant liquefied natural gas (LNG) project, he said.