Equity Oil Co. of Salt Lake City reported total revenue for the three months ending Sept. 30 of $3 million, a 19 percent decline from the $3.8 million in the same period a year ago. The company had a net loss of $33,231 in the quarter or less than a penny per share, compared to net income of $135,784 or one cent per share a year ago.

For the nine months ending Sept. 30, the company reported total revenues were down 3 percent to $9.7 million from $10 million in the same period a year ago. Net income for the nine months was $56,500, less than a penny per share, compared to $152,034, or one cent per share a year ago.Fred H. Evans, company president, said the lower earnings and revenues reflect the decline in oil prices and higher exploration expenses from 1987 to 1988.

"Although the price of oil remains volatile, our solid cash flow and strong working capital position have allowed us to proceed with our 1988 exploration program without drawing down our cash reserves," he said.

Evans said the erosion of oil prices in the first nine months of 1988 is reflected by the price of oil received at the Rangely Weber Sand Unit in western Colorado where the price averaged $15.18 per barrel during the first nine months this year, 13 percent lower than than the average price of $17.46 per barrel in the same period a year ago.

Lower oil prices were partially offset by increases in oil and gas production. Oil production in the first nine months of 1988 increased to 514,172 barrels, 2 percent higher than the 502,656 barrels it produced in the same period a year ago.