THE FALLING PRICE of oil will have an immediate impact on oil's closest competitor, the natural gas industry. Is that good for consumers who heat their homes with gas? Not necessarily, and certainly not automatically. Federal price controls and the industry's commercial contracts together have built a framework that does not respond well to sudden changes. The price controls were all based on the assumption that oil would become slowly and steadily more expensive. Instead it got much more expensive very fast in 1979-80, and now it's getting cheaper. The response of gas prices is going to be bizarre.

When oil prices went up, a lot of industrial users switched to gas. Now that they are coming down, those industries will switch back. Losing those big customers will threaten most of the pipelines with severe financial losses. During the peak years of the 1970s, they bought a great deal of very expensive gas under agreements that require them to pay for it whether they take delivery or not--the famous take-or-pay contracts. They expanded their systems, under great public pressure to end the recurrent gas shortages. As a result, their fixed costs have risen sharply. When the industrial customers drop out of the market for gas, more of these fixed costs will have to be shifted onto the remaining customers --including residential customers.

There's probably no way to shield people entirely. But legislation to make gas pricing more flexible would certainly help. The secretary of energy, Donald P. Hodel, has proposed removing most of the present controls on the prices at which gas is sold at the wellhead. But at the same time he would change the pipeline regulations to prevent them from passing on to their customers rising gas prices when they could have bought other supplies at a lower price. That's a highly promising pair of ideas. The price controls, as they have become more complex over the year, have become a floor for prices as much as a ceiling. By setting up many different categories of gas, each under its own rules, the controls have created endless inequities in pricing. Anyone who has been paying household gas bills over the past year will know how successful the controls have been in protecting the consumer. But that is the nature of controls--to create shortages in a rising market and unfairness in a declining market.

Neither the administration nor Congress is eager to take up gas legislation again. There is hardly any other subject on which as many interests contend as fiercely. But natural gas provides well over one- fourth of this country's energy. Errors in gas policy impose social and economic costs second only to those that result from errors in oil policy.