John W. Buckley, a petroleum-industry executive who once headed the worldwide network of speculative oil, gas and mineral ventures founded by his father, William F. Buckley Sr., died of heart failure Saturday at Etobicoke General Hospital in Toronto. He was 64 years old and lived in Lakeville, Conn.

Mr. Buckley, who had suffered for some time from heart and stomach ailments, fell ill shortly before a meeting of the board of directors of Canada Southern Petroleum Ltd., a company he formerly served as president.

He was the eldest son of the 10 children of Aloise Steiner Buckley and the late William F. Buckley Sr. of Sharon, Conn., and Camden, S. C. He attended elementary schools in France and England and the Millbrook School in New York, and graduated from Yale University in 1942.

After serving as an intelligence officer in Africa and France during World War II, Mr. Buckley began working in 1946 for Catawba Corporation, the oil, gas and financial consulting concern founded by his father. Deposed in Proxy Fight

The corporation served as the overseer for several small oil companies around the world. From 1958 to 1981, Mr. Buckley was its president.

In 1980, a group of dissident shareholders unseated the board of United Canso, one of the Catawba companies, in a stormy proxy fight, and Mr. Buckley was ousted as president and chairman of United Canso.

The next year the Catawba Corporation and some of its associates were ordered by the Securities and Exchange Commission to make payments and relinquish royalties totaling more than $800,000.

Mr. Buckley, although semiretired, continued as president of Pantepec International Inc., another family concern.

Mr. Buckley, an avid hunter, was a member of several fish and game clubs, and of the Racquet and Tennis Club and the Union League Club.

He is survived by his mother; three children, Mary Lee Suissman of Los Angeles; Aloise, of New York, and John M., of Washington; three brothers, James L., former United States Senator from New York, now of Munich; William F., of New York, editor of the National Review, and Fergus R., of Camden, and four sisters, Priscilla L., of New York, Jane Buckley Smith of Sharon, Patricia Bozell of Washington and Carol Learsy of New York.

Funeral services are to be held at 11 A.M. Wednesday at St. Mary's Church in Lakeville. (--obituary, Elaine Sciolino, The New York Times, New York, NY, 3 Dec 1984)