Washington area gasoline and heating oil prices increased more than a nickel a gallon during the last three weeks, and oil analysts predict that the Reagan administration's removal of controls on gasoline and domestic crude oil prices last Wednesday will add another 10 cents to local prices in the next few months. This analysis by energy experts tends to contradict the assertion by Energy Secretary James B. Edwards at his press conference on Wednesday that decontrol might increase local fuel costs by 3 to 5 cents. "I hope it doesn't cost [consumers] anything, but there may be some small cost," Edwards said. Some analysts predicted the average cost of gasoline could reach $1.53 per gallon by June. Gulf, Sunoco and Texaco, which together supply a quarter of the gasoline used in the Washington area and a good deal of the heating oil, yesterday raised prices on those products here between 1/2 cent and 3 cents a gallon. Exxon and Amoco, which supply about half the gasoline market here, raised gasoline prices 3 cents and 2 cents a gallon respectively earlier in the week. Spokesmen for all these companies except Texaco said price increases by the Organization of Petroleum Exporting Countries last December, and not decontrol, had caused these latest price increases. The OPEC increases still have not been completely passed through to consumers. Texaco's statement yesterday was ambiguous on whether decontrol helped spur its latest increase. "Undoubtedly there will be more increases now that we've had decontrol," a Sunoco spokesman said. Although Energy Secretary Edwards said that decontrol means the federal government will reap $3 to $4 billion from the windfall profits tax, officials in the District of Columbia, Maryland and Virginia said that decontrol will increase their losses of gasoline tax revenue in their jurisdictions. This will happen because decontrol will tend to raise fuel prices, which will in turn promote conservation by price-sensitive consumers -- the whole point of immediate deregulation. Since D.C. Maryland and Virginia all have a set tax per gallon rather than a percentage tax, fewer gallons sold means less revenue. Fuel conservation driven by higher prices helped make gasoline tax revenues in the District drop $3.2 million or 15 percent between 1979 and 1980, according to Billy D. Cook, an analyst in the city's Department of Finance and Revenue. Cook projects that gasoline tax revenues will drop another $1.4 million next year as conservation continues. Maryland collected $14 million less in 1980 than in 1979 for the same reason. In Virginia, revenues went up a little but only because the gasoline tax went from 9 to 11 cents a gallon in mid-year. A Washington Post price survey shows that the average price of a gallon of gasoline here now is $1.36.9, an increase of 5.4 cents a gallon or 4 percent over the price recorded just three weeks ago. Home heating oil here went up 6.9 cents or 6 percent during the same period to an average of $1.23.4 a gallon. These sharp price increases took place during a time when the American Petroleum Institute reports that worldwide and U.S. stocks of crude oil and petroleum products remain higher than normal -- a circumstance that oil analysts say should slow the passthrough of the increased cost of decontrolled oil to consumers. That slowdown means that the 8 to 10 cents a gallon that decontrol adds to the refiner's cost may not be completely passed through to consumers until next spring or summer, experts say. However, they say, 3 or 4 cents of that may be passed through fairly soon. "Look for a gradual phase-in [of the increase]. Most of it will be passed through by early June," said Mark Emond, editor of the Lundberg Letter, a respected petroleum marketing newsletter. A U.S. Energy Department analyst who asked not to be identified said that decontrol means, "You'll be seeing no abrupt rise in prices, but a gradual increase up to what the market will bear." Domestic crude oil prices were being gradually decontrolled in a program that would have fully decontrolled them by Oct. 1 this year. The Reagan administration's action simply moves that process forward several months and means that consumers will sooner be paying the higher prices that they wouldn't have had to pay until October. In other words, analysts say, consumers would have been paying the 8 to 10 cents a gallon extra by October in any case, so that the net increase in their fuel bills will not be high because the Reagan administration moved forward the date of total decontrol. But the price of gasoline should indeed be high by the summer driving season when increases caused by decontrol are added to increases from OPEC price rises and continually inflating refiner operating costs that oil companies try to pass through. Lundberg's Edmond estimates that all these factors will make gasoline 16 1/2 cents a gallon more expensive by June. That figure, added to the current average Washington price, would make the average price here in June $1.53.4 a gallon. Experts said yesterday that while the Iran-Iraq war has cooled and those countries are again exporting crude oil, a new blowup in the Middle East could send prices skyrocketing at any time by drying up world oil supplies.