Earnings rose last year for two of the nation's largest petroleum companies and largest industrial corporations, Mobil Corp. and Shell Oil Co.

Mobile Corp., parent of Mobil Oil, yesterday reported 1978 earnings reached an estimated $1.124 billion ($10.61 a share) compared with $999 million ($9.44) in the previous year. The earnings came on revenues of $36.9 billion in 1978 against $34.4 billion for 1977.

Mobil is the second largest oil producer and fourth largest industrial corporation.

Mobil's 1978 fourth-quarter estimated earnings were $332 million ($3.13), up 10.2 percent over the $301 million ($2.85) restated earnings for the 1977 fourth quarter. Fourth-quarter revenues were $10.3 billion in 1978 compared with $9.5 billion in the same period of 1977.

Earnings for 1977 were restated to reflect the retroactive application of new accounting regulations, reducing fourth-quarter earnings by $2 million and full-year earnings by $5 million.

Mobil said worldwide petroleum earnings per gallon sold were 2.2 cents in 1978 against 1.8 cents in 1977.

Shell Oil Co. said that unaudited figures show 1978 net earnings of $814 million, up from $760 million in 1977, but fourth-quarter earnings that were lower than a year ago despite higher revenue.

Per-share earnings were $5.45 last year compared with $5.28 in 1977. Fourth-quarter earnings of $192.3 million were down from the $192.7 million reported for the comparable quarter of 1977, and per-share earnings were $1.27 compared with $1.32 for the last quarter of 1977. Revenues were $2.9 billion in the 1978 quarter up from $2.6 billion in the previous year's fourth quarter.

Shell is the nation's eighth largest oil producer and 14th largest industrial corporation.

President John F. Bookout said the 1978 increased earnings were attributed to improved prices for oil and gas production and increased sales of refined products.

He said earnings from oil and gas exploration and production increased 18 percent, while earnings from oil products sales increased 16 percent. Chemical products earnings declined 27 percent because of higher operating costs and increased plant expansion costs.

Bookout said he expects about $2.2 billion in capital and exploratory expenditures this year, up slightly from last year's $2.1 billion.

Procter & Gamble Co. yesterday announced earnings increases of 15 percent in its second quarter and 13 percent in the first half ended Dec. 31 of its fiscal year on higher unit volume.

The producer of household products and foods said second-quarter earnings were $127.1 million ($1.54 a share) on sales of $2.249 billion compared with earnings of $110.9 million ($1.34) and sales of $1.929 billion in the previous second quarter. The sales gain was 17 percent. First-half earnings rose from $260.9 million ($3.16) to $294 million ($3.56) as sales increased 17 percent from $3.862 billion to $4.535 billion.

The recovery of grocery coffee sales enabled General Foods Corp. to lift its profit 79 percent in the third quarter ended Dec. 30 and 49 percent for the nine months.

Profits for the quarter were $69.01 million ($1.38 a share) on sales of $1.381 billion compared with $38.52 million (77 cents) a year earlier on sales of $1.371 billion.

Nine-month profits were $175.3 million ($3.51) on sales of $4.02 billion compared with $117.69 million ($2.36) a year earlier when sales were $3.828 billion.

Chairman James L. Ferguson said that besides the recovery in coffee sales, General Foods benefited from the introduction of new products such as carbonated candies, which have been successful both in Europe and the United States.

Monsanto Co. reported higher sales and earnings for 1978.

Sales were $5 billion, an increase of 9.2 percent from 1977. Net income was $302.5 million ($8.21 a share) compered with 1977 figures of $275.6 million ($7.37).

Net income for the fourth quarter was $43.9 million on sales of $1.3 billion compared with net income of $21.3 million on sales of $1.09 billion for the last quarter of 1977. The 1977 results were affected by exchange and translation losses of $22 million, whereas similar losses last year were $4.9 million.

John W. Hanley, Monsanto's chairman and president, said: "For the fourth quarter, results from operations in the United States were encouraging; volume improvements were registered by almost all units of the corporation. The weakness of the U.S. dollar -- while resulting in continuing exchange and translation losses -- helped to stimulate gains in export sales as U.S. manufactured products became increasingly competitive in world markets."