Short answers, pulled from the story.
The 1980s oil glut resulted from a combination of conservation efforts reducing consumption and increased non-OPEC production. Oil prices peaked in 1980 at over US$35 per barrel, triggering a 13% drop in consumption across industrial nations between 1979 and 1981. Major non-OPEC fields in Siberia, Alaska, and the North Sea developed during this decade to supply global markets.
Oil prices collapsed to as low as $7 per barrel following Saudi Arabia's decision to abandon its role as swing producer in late 1985. The inflation-adjusted real value of oil fell from an average of $78.2 in 1981 to $26.8 per barrel by 1986. Time magazine noted that such a glut caused tighter development budgets in exporting nations by June 1981.
Falling oil prices contributed significantly to the final collapse of the Soviet Union, which had been a major oil producer before the glut occurred. The drop of revenues undermined the state's ability to fund operations while economic instability grew alongside political unrest within Soviet borders. This financial pressure accelerated the dissolution of the Soviet state due to the combination of low oil prices and high spending.
Commercial exploration developed major non-OPEC oilfields in Siberia, Alaska, and the North Sea during the 1980s. Smaller non-OPEC producers including Brazil, Egypt, India, Malaysia, and Oman doubled their output between 1979 and 1985. These smaller nations reached a total production of 3 million barrels per day while the Soviet Union became the world's largest producer of oil by this time.
In late 1985 there were nearly 2,300 rigs drilling wells in the United States but only barely 1,000 active rigs remained a year later. The number of U.S. petroleum producers decreased from 11,370 in 1985 to 5,231 in 1989 according to data from the Independent Petroleum Association of America. Oil producers held back on searching for new oilfields due to fear of losing investments as market conditions worsened.