(MONEY Magazine) – Remember 1986, when a temporary oil glut caused crude prices to sink to $10 a barrel? Investors who ignored experts' warnings of a prolonged period of low oil prices and bought languishing energy stocks sure do. They made 25% to 60% on their money in a year. Well, it may be 1986 again. OPEC's disarray has allowed an oversupply of oil, and prices have dropped from $21 per barrel last spring to $15. And many energy stocks are down 20% or more, creating a buying opportunity, says James Solloway, director of research at Argus Research in New York City. Here's a look at six -- two integrated firms that refine and market oil as well as produce it, two exploration firms and two natural gas companies -- that currently top analysts' buy lists. All trade on the New York Stock Exchange. -- Integrated oil companies. Among the international giants, Royal Dutch Petroleum (ticker symbol: RD; $104.25 a share; 4.5% yield) is the favorite of analyst Frank Knuettel at Prudential Securities in New York City. One reason he singles out Royal Dutch (estimated 1994 revenues: $105 billion) is that more than three-quarters of its profits comes from international operations that will likely improve this year as the Japanese and European economies recover. Knuettel thinks the stock can rise 15% to $120 a share, for a 20%- plus total return (including dividends) over the next 18 months. Of the smaller U.S. integrated companies, analyst Michael Mayer at the Burlingame, Calif. office of Wertheim Schroder recommends $8.3 billion Unocal (UCL; $28; 2.9%). The company is boosting its oil and gas production and could pump up earnings 38% or more this year, says Mayer. He thinks the stock could reach $32 over the next 18 months, for a total return of 19%. -- Independent producers. These smaller companies offer larger potential gains (with greater risks) than integrated oils do. Among them, Paine Webber analyst David C. Bradshaw favors $420 million Noble Affiliates (NBL; $25.50; 0.6%). "Last year, their drilling was very successful, particularly in the Gulf of Mexico," says Bradshaw. He thinks the stock could hit $40 over the next 18 months. That's a 58% return from here. More aggressive investors may want to consider $100 million Triton Energy (OIL; $31; no yield), says analyst Thomas R. Driscoll at Salomon Bros. in New York City. "Triton produces very little oil today," he says. Indeed, the company has posted losses since 1987. "But Triton has discovered two big oilfields in Colombia, in partnership with British Petroleum," he says. The fields could be producing 800,000 barrels a day by 1998. Driscoll thinks that Triton stock could rise 29% to $40 over the next 18 months. -- Natural gas companies. A conservative pick in the natural gas group is $2.4 billion Panhandle Eastern (PEL; $22.75; 3.5%). "The company's earnings are largely bulletproof," says analyst John E. Olson at Merrill Lynch in Houston. That's because instead of producing gas, Panhandle makes most of its money carrying gas in its pipelines for a fee. Nonetheless, the stock fell 16% in the past five months along with other energy shares, says Olson. He expects it to rebound to $28 over the next 18 months, for a total return of nearly 28%. Analyst Steven Parla at CS First Boston in New York City recommends $9 billion Enron (ENE; $28.25; 2.7%). "The company will probably increase earnings more than 15% in 1994," he says. Reason: Enron's gas services division, which markets gas, has been very successful, and its power division has a lucrative sideline building power plants. Parla thinks the stock can surpass its 1993 high of $37 within 18 months, for a 35% total return. That would raise the energy level of any portfolio.

CHART: NOT AVAILABLE CREDIT: NO CREDIT CAPTION: PROFITS OF UP TO 58% These six stocks look inexpensive, according to analysts, and could earn from 19% to 58% over 18 months.