Some owners of Washington Gas Light Co. shares must have been disappointed last week.

In a report on 1981 earnings, the District-based natural gas distributor said overall profits rose by $1.16 million over 1980's total to $19.2 million but that per-share profits declined by 15 cents to $3.36, with more shares outstanding after a common stock offering in May.

The overall profits were higher because of increased customer rates and a larger volume of gas sold, offset by a substantial boost in interest costs ($26.8 million in 1981 vs. $18.6 million in 1980).

On the surface, it looks like a rather typical report from a regional natural gas utility company in an era of record interest rates.

But wait a minute. Isn't this the same firm that became an overnight stock market hot spot last year, by striking huge natural gas deposits in the Midwest and attracting speculative investors who pushed the price of shares to abnormally high levels?

Indeed, Washington Gas Light is that company, and the disappointment last week was that the 1981 results provided no evidence that the company's bottom line is yet feeling anything but a very modest impact from extensive drilling for natural gas. In addition, Washington Gas appears to have little information itself about what's happening at some two dozen wells in Louisiana and Oklahoma, in terms of success or failure and the ultimate impact on the D.C. company. o WGL's credit, the company has been very reluctant to fuel speculation about a possible bonanza from participation in natural gas exploration. The boom in Washington Gas stock last year was based primarily on reports from Oklahoma, coupled with conclusions reached by Wall Street analysts.

For the most part, Washington Gas has merely confirmed various reports from the gas fields or provided a very succinct summary of drilling operations in which it has an investment. Over the weekend, for example, the Washington company mailed to its stockholders a printed report on 1981 operations. Included is a small, separate sheet of paper purporting to be a report on gas exploration.

The information is murky, at best. WGL notes that it has a subsidiary, Crab Run Gas Co., which holds leases on properties containing one producing well in Louisiana, 10 shallow wells in Oklahoma and one deep well (below 15,000 feet) in Oklahoma. And Crab Run has interests of varying amounts (3 percent to 25 percent) in 13 additional deep wells in Oklahoma--which are listed by name, depth on Jan. 21 and WGL's interest. That's all.

Company spokesman Paul Young said he has no further information on these wells, one already drilled to a depth of 18,150 feet. "We have a long way to go before knowing if they are produceable," he said.

But some area stock brokers are reading between the lines, and they think Washington Gas is something like a sleeping giant. One broker estimated that four of the wells in Oklahoma are close to a level where production of gas will follow shortly. The significance of deep wells--below 15,000 feet--is that natural gas discovered and produced is exempt from federal price controls.

In addition, the cold weather of January probably resulted in a record month for the company in terms of its service throughout metropolitan Washington. One estimate last week was that profits for the month itself would be up 47 cents a share from the same period in 1980. For the first time in history, WGL delivered more than 10 million therms of natural gas in a 24-hour period on at least two days during the recent cold wave.

The prospect of higher earnings during the cold weather coupled with new speculation about natural gas drilling were the main factors in trading of Washington Gas stock last week. After a 14 percent decline in the prior month, WGL shares on the New York Stock Exchange last week rose $1.75 to $28.75 on a volume of 62,800--double the trading in the previous week.

A year ago, when news first was circulated that Washington Gas was part-owner of a huge natural gas find near Eakly, Okla., WGL's stock was trading at under $20 a share. Before long, the moribund stock had jumped to more than $40 and hit a record high of $43.38. The stock bounced up and down after that, but began to sink in recent months. Investors who bought Washington Gas stock in hopes of a quick price appreciation began to realize that discovery and harnessing of natural gas is a costly and long process.

Take Tom Cat, for example. It was Tom Cat #1 that roared with thunder one year ago and started the WGL boom. The 15,335-foot deep well was delivering 100 million cubic feet of natural gas a day into the air, one of the biggest strikes in history. Washington Gas had a 19 percent interest in the well, drilled by Ports of Call Oil Co.

But in June, because of mechanical problems, that well as plugged and abandoned. A second well was started on nearby land within the same lease, called Tom Cat #1A. It, too, encountered mechanical difficulties. Now, Ports of Call is drilling Tom Cat #2A and as of Jan. 21, it was at a depth of 4,295 feet. It is obvious that a huge reserve of natural gas is hiding below that Oklahoma farm land, but sophisticated drilling operations over more than 12 months have not been able to harness this find and make it available to the natural gas pipeline transmission network. t another site in Caddo County of Oklahoma, Washington Gas has a 9.6 percent interest in a well that was completed last Aug. 21. This well was successfully stabilized and began to produce 6 million cubic feet a day. A contract was signed last Sept. 8 with Transwestern Pipeline Co., with gas being sold at a base price of $8.48 per thousand cubic feet. Industry reports placed the overall price as high as $9.30 a thousand cubic feet, among the highest prices ever paid for natural gas.

But WGL's interest in this well is less than 10 percent and production is at a far lower level than once anticipated for the Tom Cat site, which is about a mile away. So the impact on WGL's earnings is smaller.

Still, Washington Gas is unusual among regional natural gas distributing utilities in the extent of involvement in exploration. Over the years, if more wells are successful, WGL will find profits flowing to its bottom line as gas flows into the pipelines. The record of 1981 shows how much this is a risky, long-term prospect and not an overnight bonanza.