A Neiman-Marcus oil well - spouting Washington red tape - yesterday opened the Mazza Gallerie, a 60-store enclosed shopping center that developers predict will become the center of a new downtown Northwest Washington.

Only one other store - a branch of The Limited a moderately-priced women's wear chain that was still waiting for its sign to be delivered opened yesterday.

But a greenery shop - Plants by Ponte Verde - and a unit of B. Dalton, the bookstore chain of retail giant Dayton Hudson Corp, say they will open this week and another dozen stores are expected this month.

Seven more openings are scheduled by Christmas and nine additional retailers have announced plans to open next year and the center will be filled by spring, said a spokesman for Shannon & Luchs, the managing agent.

Likening the building to Watertower Plaza, a seven-story shopping arcade in Chicago, the real estate man said the project "is more like a downtown than a suburban mall."

"It's in the natural center of the traffic flow from Lord and Taylor to Woodward and Lothrop," he said.

"If Washington is ever going to have a Fifth Avenue or a North Michigan Avenue, this area is it."

Several designer boutiques reportedly are among the other shops that have leased space in the five-level mall which sits atop four layers of basement parking.

Renting is 90 per cent complete, the agents said, and the final tenants are expected to move in by April, about four years behind the originally scheduled opening date. Construction problems, strikes and problems with financing the major delays.

Estimates are that the entire complex will generate annual sales in the $20 million to $30 million range.

About half the retail space - 145,000 square feet - will be occupied by the smaller shops. Neiman Marcas has about 120,000 square feet or space, 97,000 square feet of it used for retail selling.

The Neiman-Marcus store is roughly half the size of Blooming late's, the store to which it is most frequently compared.

The two newcomers to Washington retailing take almost diametrically opposed approaches to merchandising.

While Bloomingdales calls itself "trendy" Neiman Marcus buzz-word is "taste."

While Bloomingdales fills its stores with merchandize and encourages customers to prospect for their favorite finds. Neiman-Marcus as vice-chairman Richard Marcus points out, "edits" the selection for the customers.

When Bloomingdales opened here, one of its executives said, "We realize there are two kinds of shoppers, those who like quiet and peaceful surroundings and those who like to be stimultated. Our customers like to be stimulated."

In contrast, Marcus said his company seeks to create a calming ambiance, encouraging customers to take a chair and allow a sales person to get the merchandise they want to look at.

Nearby Lord and Taylor prides itself on offering the latest fashions at several price levels, but there is no such stratification at Neiman-Marcus. Prices are not as stratospheric as the sotre's oil-millionaire image might indicate, but big ticket items make up a bigger share of the sales than at other stores.

While Neiman-Marcus' apparel departments go head-to-head with Lord and Taylor. Saks Fifth Avenue and Woodies in many categories, there is no attempt to compete for the basic business that is the bread and butter of the department stores.

Unlike the vast majority of soft-goods retailers. Neiman-Marcus relies on commissions for its sales persons. A successful seller in a high-ticket department can make $25,000 a year or more company officials say.

That personnel selling carries over into advertising and sales promotion as well. Neiman Marcus spends more more of its advertising budget on direct mail campaigns and less on day-to-day newspaper advertising than other big retailers.

The company won't say how much of its business is generated by its famous Christmas catalog, but interviews with first-day shoppers indicated the book is an important lure.

Picking out a $25 stripped Madras shirt from the catalog for her husband for Christmas, one woman commented, "the whole place is like a year-round Christmas present."

Mrs. Michael McManus of Potomac, whose grade school daughter will be the first on the block with a Neiman-Marcus dress, confessed, "I've waited for the place to open. It's just nice, they have very nice things."

Within an hour after Mayor Walter Washington, wearing a cowboy hat, had turned on the symbolic oil well. William Marjel of Vienna had picked out a bottle of cologne and a $20 knit shirt. "I just enjoy shopping here," he said. "When we lived in Dalls, it was the place to be."