Three House Republicans attacked the Carter administration figures on natural gas costs and benefits today, charging that deregulation of the fuel actually would save American consumers billion of dollars in the long run.

Reps. Clarence J. Brown of Ohio, James M. Collins of Texas and David A. Stockman of Michigan said at a joint press conference that false assumptions were behind President Carter's charge that unregulated natural gas would be a "ripoff" of consumers.

"I want to tell you Dallas lives under deregulation," said Collins, "and we've had a 52 per cent increase in gas prices . . . but industry was able to keep operating because people paid enough to keep the gas available, and they thought it was a bargain to keep it that way and keep their paychecks coming in."

The congressmen presented to studies that calculated deregulation would save consumers $48 billion over Carter's program by 1990. This, they said, was because Carter's proposal would stimulate production of 3 trillion cubic feet of gas less than deregulation would, and energy users would have to turn to more expensive fuels.

In addition, costs of pipelines and distribution would have to be paid by fewer consumers than under decontrol and those consumers would therefore spend much more.

An administration spokesman dismissed those criticisms, "categorically. That's the major difference between them (the Republicans favoring deregulation) and us. 'We're saying higher prices (to producers) cost a fortune and you get very little more supply for it. Money can't change the facts of nature."

The argument over deregulation of natural gas prices, which now are controlled at the interstate level only, has centered on producers' arguments that prevailing prices are lower thantheir costs and provide no incentive for new exploration.

The administration has responded that there is no evidence higher prices would produce significantly more gas using conventional methods, and that fuel obtained by nonconventional extraction methods would not be subject to price controls under Carter's plan in any case.

The Republicans said experience in Ohio and Texas fields showed that dereguation there cause production to rise sharply, while low prices for gas from a New Mexico field committed to interstate use resulted in no production there. "Prices don't justify development of this field: it just sits there," said H. A. Mercklein author of a study done at Collins' request.

"If you want to call this hoarding yes, there's plenty of it. But gas here and in other fields will appear as soon as prices go up." he said.

The studies said the Carter plan overstated the amount of known gas reserves that would immediately rise in price under deregulation.

Most of the gas is already contracted out at current prices, they said. The administration spokesman responded that deregulation under Republican proposals would allow wells to be dug in existing fields and classed as new uncontracted gas. "Our estimates are conservative," he said.

Brown ranking minority member of the Commerce Energy and Power Subcommittee which is considering Carter's gas pricing measures, said another test vote on the plan would probably come before the end of the week. The full committee voted 22 to 21 last week to approve Carter's proposal for higher control levels.