UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

~~Washington~~WASHINGTON, D.C. 20549

FORM 6-K

~~REPORT~~Report OFof ~~FOREIGN~~Foreign ~~PRIVATE~~Private ~~ISSUER~~Issuer Pursuant to Rule 13a-16 or 15d-16 Under the

Pursuant to Rule 13a-16 or 15d-16 under the

Securities Exchange Act of 1934

~~For~~ March 2228, 2013

Commission File Number: 1-6702

NEXEN INC.

(~~Translation~~Exact name of registrant’s ~~name~~as ~~into~~specified ~~English~~in its charter)

801- 7th Avenue S.W.

Calgary, Alberta, Canada, T2P 3P7

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F o Form 40-F X þ

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ~~____~~o

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ~~____~~o

DOCUMENTS FILED AS PART OF THIS FORM 6-K

See the Exhibit Index to this Form 6-K.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	NEXEN INC. (Registrant)
	NEXEN INC. (registrant)
Date: March 22, 2013	By:	/s/ Rick C. Beingessner
March 28, 2013	By:	/s/ Rick C. Beingessner
		Name: Rick C. Beingessner
		Name:	Rick C. Beingessner
		Title: Assistant Secretary
		Title:	Assistant Secretary

Form 6-K Exhibit Index

Exhibit Number	~~Description~~	Description
4.1	Fourth Supplemental Indenture dated March 22, 2013 to the Senior Debt Indenture dated May 4, 2007 among CNOOC Limited, Deutsche Bank Trust Company Americas and Nexen Inc.
99.1		News Release dated March 28, 2013
4.2	Seventh Supplemental Indenture dated March 22, 2013 to the Trust Indenture dated April 28, 1998 among CNOOC Limited, CIBC Mellon Trust Company, The Bank of New York Mellon and Nexen Inc.

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