Gulf Oil Corp. yesterday reported that is 1976 profits were $116 million, or 16.6 per cent, higher than in 1975 and represented the second highest earnings in the company's history.

Earnings of $816 million ($4.19 a share) compared with $700 million ($3.60) in 1975. Revenue in 1976 increased by 15 per cent to a record $18.44 billion from $16.04 billion in 1975.

Fourth-quarter earnings of $218 million ($1.12) were 28.2 per cent higher than the $170 million (88 cents) earned a year earlier. Revenue for the three months ended Dec. 31 was $5.12 billion, 22.8 per cent higher than the year-earlier $4.17 billion.

"During 1976, our worldwide refining, marketing and transportation operations became meaningful contributors to earnings, accounting for approximately 20 per cent of our $682 million in petroleum profits compared with breakeven operations a year ago," president James E. Lee said.

Lee said chemical earnings increased to $148 million and contributed 18 per cent of the company's total earnings. Gulf's Canadian yellowcoke production of uranium also began to provide earnings after years of heavy investment.

Earnings and revenue of Phillips Petroleum Co. both increased significantly during 1976, the company announced yesterday.

Phillips estimated its 1976 earnings at $412 million, an increase of $69 million over 1975, and revenue at $5.8 billion, up $600 million from the previous year. The company reported earnings of $5.39 a share compared with $4.50 a share in 1975.

Martin said fourth-quarter earnings were $126 million ($1.65 a share) on revenue of $1.6 billion compared with $104 million ($1.37 share) on revenue of $1.4 billion in the 1975 fourth quarter.

Union Oil of California yesterday reported that is preliminary net earnings were up 18.2 per cent for the fourth quarter and 15.5 per cent for all of 1976 compared with the previous year.

Earnings for 1976 were $268.8 million, up from the $232.8 million of 1975, the company said. The fourth-quarter net earnings were $80.8 million compared with $68.4 million the same period in 1975.

Total revenues in 1976, excluding state and federal excise taxes, were $5.4 billion in

Union Oil said the increase in earnings came from increased sales of refined products, higher natural gas prices and higher investment tax credits.

The company said its net worldwide production of crude oil averaged 300,400 barrels daily in 1976 compared with 313,000 barrels daily in 1975. Average natural gas production was down about 3.5 per cent, the company reported.