House and Senate conferees agreed yesterday on the terms of the crude-oil tax President Carter proposed last spring to accompany decontrol of domestic crude oil prices.

The tax as approved yesterday would raise $227.3 billion between now and the end of 1990 if oil prices rise only 2 percent a year faster than prices generally.

One oilman watching the conference predicted a much faster rise in oil prices and a $400 billion yield from the tax if it stays in effect for the entire period.

The compromise means the new tax would capture slightly less than one-fourth of the total increase in oil industry revenues due to decontrol. Corporate and personal income taxes will capture a larger share of the revenue increase.

Under the compromise, a 70 percent tax would be levied on most oil from fields in production before this year. The tax would be payable on the difference between the oil's actual selling price and a base price averaging $13 a barrel adjusted quarterly for inflation.

This means that oil discovered before 1973, now controlled at about $6 a barrel, can under decontrol move to $13 plus the inflation adjustment before any of the special tax is due. About 2.6 million barrels of daily U.S. production falls in this category.

Another 2.9 million barrels of current production known as upper tier oil, which was discovered since 1972, is selling at a controlled price of about $14.50 a barrel. About 75 cents of that amount would be subject to the tax. Meanwhile, 4.6 percent of upper tier oil is being decontrolled each month beginning this month, and the tax would also be due on the added $15 or so that will bring in the market.

A 30 percent rate would be charged on oil discovered since 1978, oil produced with so-called "tertiary" recovery methods that are expensive, and heavy oil that must be heated before it will flow. In the case of these categories of oil, the average base price would be about $16.55 a barrel.

Oil from pre-1979 wells that produce only 10 barrels a day or less, known as stripper oil, would be taxed at a 60 percent rate with an average base price of $15.30. Stripper oil has not been subject to price controls since 1973.

The conferees, settling the most difficult point of disagreement between the House and Senate members, agreed that independent oil producers should qualify for lower rates on the first 1,000 barrels of their daily production. The compromise calls for a 50 percent rate instead of 70 percent on most pre-1978 oil and a 30 percent rate on stripper oil.

The independents would pay about $22.5 billion of the $227.3 billion total. The Senate had exempted them entirely from any tax on that first 1,000 barrels a day, while the House had given them no special treatment.

Still undecided last night were the terms under which the tax would be phased out. Most oil industry representatives would prefer the Senate approach, with the phase-out beginning whenever a certain amount of revenue has been collected. The House members want a specific date.

Also still to be resolved are a long series of energy-related tax credits in the Senate version of the bill. Credits for individuals for purchase of wood stoves, heat pumps and so forth would be worth $8.7 billion through 1990, according to estimates by the Joint Committee on Taxation. Other credits would reduce business taxes by $17 billion.