Energy Secretary Charles W. Duncan Jr. today reassured nine Northeast governors that the nation's most oil-dependent region will have enough home heating fuel this winter and a federal subsidy to help pay for it.

Duncan said he would lobby Congress for $150 million in addition to the $250 million already requested by the White House to help poor and middle-income people meet fuel bills, which have nearly doubled this year.

The funds would be appropriated and administered separately from "windfall profits" tax income reckoned on in the president's energy program, Duncan said in his first foray out of Washington as energy secretary. He took office last week.

"We intend to see that the Northeast doesn't have heating oil problems in the coming winter," he told reporters after a two-hour meeting with the governors. "I'll exercise whatever authorities are available to ensure that that doesn't happen."

His power, Duncan said, includes the authority to order a boost in heating oil production, now set at between 22 and 23 percent of refinery output, and to reallocate stock from other regions which depend primarily on natural gas.

He promised to press the oil companies to move home heating oil from the massive refinery storage tanks to local distributors and consumers before prices jump again and winter weather hampers transport.

The step, if taken, would represent a shift in the administration's emphasis on the refinery stockpiling of 240 million barrels of home heating oil, a goal announced by President Carter during a trip to New Hampshire last spring.

"It doesn't do any good to have primary storage if it has to be barged on a frozen canal," said New Jersey Gov. Brandan Byrne. "The fact that 240 million barrels of home heating oil is somewhere doesn't mean it's where we need it."

Duncan said that by the end of October, a month after the Department of Energy's original target date, the nation will have a full supply of home heating fuel, "assuming continuation of a buildup weekly of about 7 to 8 million barrels."

He added that a full account of home heating oil stocks would not be available until about the third week of September.

The governors, many of whom wasted no affection on former energy secretary James R. Schlesinger Jr., praised Duncan.

New York Gov. Hugh L. Carey was the most enthusiastic: "We have a very forthright secretary of energy. I think it's been one of the most productive meetings I've ever held with a Cabinet secretary."

However, he said later that the $400 million in crisis intervention funds proposed by the secretary may not be sufficient, and he urged Congress to authorize a $1 billion line of credit to ensure that poor and middle-income families could pay fuel bills and insulate their homes.

"It would prevent people from abandoning their homes because they can't keep them heated," said Carey.

Duncan endorsed a plan by the Coalition of Northeast Governors to provide loans, loan guarantees, equity capital, technical and legal assistance, and would coordinate energy programs for the region.

An investment of $50 billion over 10 years would save the northeast 1 million barrels of oil a day and $7 billion annually through alternative energy projects, according to the plan's authors.

The governors also used the meeting to lobby Duncan on individual state energy programs. Gov. Richard L. Thornburgh of Pennsylvania, a leading coal-producing state, called for the development of Northeast coal resources, which he said could meet the region's energy needs for the next 60 years.

He suggested "a reexamination of every environmental standard to determine its efficacy in this modern-day society without sacrificing our environmental integrity."

And Massachusetts Gov. Edward J. King argued for a waiver of environmental regulations currently frustrating the conversion of utility plants from oil to coal-burning status.

Duncan says he will consult with Environmental Protection Agency Director Douglas Costle later this week, and noted that air-pollution regulations are not within the jurisdiction of the Energy Department.