Thousands of grass-roots volunteers for the Alliance for Energy Security will be out knocking on doors in selected cities and towns across the country today, urging their neighbors to fight the "big-time Washington lobbyists" by contacting key congressmen to urge total decontrol of natural gas.

Few of these volunteers have been told, however, that the Alliance for Energy Security is a $1 million front for the Natural Gas Supply Association, which represents major oil companies and other large producers that stand to gain billions of dollars in profits from full decontrol.

The Alliance for Energy Security, which has no permanent office and no professional staff, consists largely of Matthew A. Reese Jr., a Virginia public relations consultant hired to organize the massive telephone and direct-mail campaign that is culminating in today's canvassing effort.

John Paul Johnson, the association official in charge of this public relations project, which is being funded by a special assessment of NGSA members, said he expects "about 40,000 volunteers will be out canvassing and distributing literature" today.

"Saturday is a key day around the country for our first phase," he said.

Although Johnson refused to disclose where the alliance is concentrating its efforts, industry sources said Reese has targeted the districts of about 15 "crucial" members of the House Energy and Commerce Committee, which will consider decontrol legislation this fall.

"Even for $1 million, it can't be a nationwide effort," an industry source said. "None of these grass-roots efforts comes cheaply. When you start mailing letters in any quantity, you run into a bundle."

Johnson said the NGSA decided to form the alliance "a couple of months ago" in an effort to counter widespread "political concern and fear" on Capitol Hill that voting for decontrol would be unpopular with constituents battered by two winters of soaring gas prices.

"We thought we would see if people would volunteer to let their officials know that it was okay to support deregulation," Johnson said.

So the alliance sent out thousands of Mailgrams blaming the fact that "the price of natural gas has more than doubled" since 1978 on "Washington's latest round of price controls," and warning that, because of these controls, "We could be facing shortages as early as 1985."

The Mailgram urged people "willing to speak out" against controls to volunteer to "become our personal representative in your neighborhood" by calling (800) 368-5041.

A number of callers found the persons manning the phone bank curiously evasive, however.

Where, for instance, is the Alliance for Energy Security located?

Some callers were told that the office was in the District of Columbia, others were told McLean, a few were told Arlington. No one apparently has succeeded in getting a specific address for the new grass-roots organization, though one was told Jones Branch Road in McLean.

"I'm sorry, they don't want me to give that out," Kevin Moore, a research associate who answered the phone, said yesterday. Moore said he was in McLean, but his boss, whom he identified as John Paul Johnson, was "in the downtown office."

Moore declined to provide a phone number or address for that office, either.

Johnson also refused to supply a street address for the alliance's office, although he insisted that it had its own office.

He did confirm that Reese's firm, Communications Management Inc. at 1925 North Lynn St., Arlington, had been retained "to help put the program together for us."

Reese declined to discuss any activities on behalf of the Alliance for Energy Security, however.

"We don't do that, or even confirm we are working for someone or not," Reese said. "I can't even confirm that I am working for them."

Johnson said that the financial information provided by industry sources--a $1 million war chest for the alliance funded by a special assessment of up to $45,000 on NGSA members--"is in the ballpark."

He also said the effort is being directed by an advisory council headed by Charles J. Cicchetti, a former chairman of the Wisconsin Public Service Commission. Cicchetti did not return phone calls.

Others listed as members of the advisory council include retired Gen. John Singlaub, who resigned from the Army under pressure after a public dispute with President Carter over the size of U.S. forces in South Korea; Rabbi Herzel Kranz of Silver Spring, a member of the National Council of the American-Israel Public Affairs Council, and Dr. Hendrik Houthakker, a Harvard economist.

Houthakker, who confirmed that he had agreed to serve "on an advisory committee of some sort" at a friend's request, said he had "not played any role" to date and was not being paid for participating. "I was somewhat afraid they might ask me for a contribution," he said.

Meanwhile, the deputy director of the American-Israel Public Affairs Council called The Washington Post yesterday to emphasize that Kranz was serving on the alliance in strictly a private capacity.

"I just want to make it clear that AIPAC does not in any way, shape or form endorse what this alliance is doing," said Arthur Chotin, deputy director. "We do not get involved in domestic energy legislation. We are not involved."

The congressmen whose districts will be canvassed today reportedly include Reps. Philip R. Sharp (D-Ind.), Doug Walgren (D-Pa.), James C. Slattery (D-Kan.), Timothy E. Wirth (D-Colo.), Mickey Leland (D-Tex.), John W. Bryant (D-Tex.), Wayne Dowdy (D-Miss.), Al Swift (D-Wash.), Mike Synar (D-Okla.), Edward R. Madigan (R-Ill.), Bob Whittaker (R-Kan.), Thomas J. Tauke (R-Iowa), Dan R. Coats (R-Ind.) and Michael G. Oxley (R-Ohio).