Enbridge Inc., Canada's largest pipeline company, filed a mixed shelf offering of up to $7 billion with the U.S. Securities and Exchange Commission (SEC) on Aug. 22, according to a SEC filing.

The company said the proceeds from the sale of the securities are not expected to be applied toward any specific project, but will be added to Enbridge's funds for general corporate purchases.

The mixed shelf will include debt securities, common shares and preference shares; and the prospectus is valid for 25 months, according to the filing.

Enbridge has been steadily expanding its North American pipeline network, which carries the bulk of Canadian crude oil exports to the U.S.

Earlier this month, it acquired a minority stake in the Bakken Pipeline system through a joint venture, and also won the auction for a stake in EnBW's Hohe See, one of Europe's largest offshore wind power projects, according to a source familiar with the matter.