These include Mexico, where output from the country's biggest oil field is declining sharply; Russia and Canadaa, where producers of tar sands have shut down some operations that are becoming uneconomical at today's lower oil prices.
In Mexico, political squabbling between the governing party and the opposition has frozen efforts to open up the oil sector to foreign investments while the country's largest oil field is declining at an alarming rate.
At the same time the field was declining, there have been tremendous breakthroughs in the brain sciences.
While the field was declining, Sir Philip described it as a marvel of "advances in well technology" that had, in four years, produced additional production and "substantial additional reserves," according to an account of remarks he made on March 9 , 1999 that is posted on Shell's Web site.
Classical music education might be alive and well in China, but in the US and to a lesser extent Europe, the field of study is declining.
Ron Denhardt of WEFA, an industry consultancy, reckons that the rate at which output from America's offshore gas fields is declining has risen in recent years, from below 20% a year to well above 40%.
Not counting exploitation, today's mature fields are declining by an average of 7-8% per year.
Ms Sen says that some of the country's older fields are declining at an annual rate of 15%.
The country's most important producing fields are found in the Maracaibo basin in the west; these mature fields are declining in production.
The country's oil fields were declining, exploration was all but halted, and Libya was forbidden to import new oil extraction technology.
Truth is these fields are declining in reserves by some 6% to 7% a year.
