Some natural gas has been held back by producers in the Gulf of Mexico, but much of it for sound economic reasons and not enough of it to have saved the nation from this winter's shortages.

Those are the conclusions in a report by the staff of the Federal Power Commission, which said that there is as much as 300 billion cubic feet of natural gas in what are called dedicated nonproducing reserves" that could be pumped from wells faster than gas producers have said they will produce the natural gas.

"It is feasible to accelerate production from most of the larger nonproducing reservoirs," the FPC staff report said. "But with a few exceptions, most producers have indicated that they will not accelerate production voluntarily and that incentive prices or higher rates will not induce voluntary acceleration."

The United States normally consumes 57 billion cubic feet of natural gas daily, a figure that has climbed to 100 billion cubic feet a day this winter. The reserves the FPC staff said they held back amount to about three-day supply of gas.

The FPC report said that producers denied holding back any gas fields to wait for higher prices. Producers said they held back some wells because of a shortage of drilling rigs and pipe and because hurried-up production might damage some fields and cause gas to be lost.

Despite those arguments, the FPC report said that some reservoirs within gas fields could have been tapped as early as last year without doing damage to other reserves.

The FPC staff report did not criticize producers for holding back wells and did not say they should have accelerated production from the wells.

It did say however, that the FPC should make "a policy decision" on whether it has the right to order some of the wells into early production.

Foremost among candidates for accelerated production were fields the FPC said are owned by the Texaco Co. in the Lighthouse Point and Tiger Shoals regions of the Gulf of Mexico. The report said six Texaco fields in those regions contained 164 billion cubic feet of gas that Texaco does not plan to produce until March, 1979.

The staff report said two of the six fields are in shallow water, easily accessible to pipelines and structured in such a way that tapping into one or two reservoirs of the fields at an early date would not damage other reservoirs within the fields.

The FPC report also identified a field owned by Mobile Oil Corp. that contained 26 billion cubic feet of gas that Mobil will not produce until 1981 that the FPC staff said could be produced sooner. Also identified in this same category were fields owned by Superior Oil Corp. and Union Oil Co. containing 22 billion cubic feet of gas, respectively.

Meanwhile, Federal Energy Administrator John F. O'Leary sent a telegram to the governors of the six New England states saying the FEA had begun an investigation to determine whether some heating oil distributors there were charging consumers excessive prices.

"We have begun an intensive review of allegations of excess prices," O'Leary said in the telegram. "We urge you to supply us with names if you have them so that the FEA can go in and audit these firms and advise you on its findings."

Heating oil is reportedly being sold at prices in excess of 50 cents a gallon in New England where the wholesale price is less than 40 cents. A markup of 5 or 6 cents a gallon to retail customers is considered adequate.