EXHIBIT 4.9
                                                                    -----------



                           DATED AS OF MARCH 11, 2002



                                   NEXEN INC.

                  (FORMERLY CANADIAN OCCIDENTAL PETROLEUM LTD.)

                                       AND

                            CIBC MELLON TRUST COMPANY





                          THIRD SUPPLEMENTAL INDENTURE

                                     TO THE

                                 TRUST INDENTURE

                           DATED AS OF APRIL 28, 1998

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                                TABLE OF CONTENTS

1.       INTERPRETATIONS AND AMENDMENTS.......................................2

         1.1.     SUPPLEMENTAL INDENTURE......................................2
         1.2.     DEFINITIONS IN TRUST INDENTURE..............................2
         1.3.     INTERPRETATION NOT AFFECTED BY HEADINGS.....................2

2.       NOTES................................................................2

         2.1.     FORM AND TERMS OF NOTES.....................................2
         2.2.     ISSUANCE OF NOTES...........................................4

3.       REDEMPTION OF NOTES..................................................4

         3.1.     REDEMPTION OF NOTES.........................................4
         3.2.     ADDITIONAL DEFINITIONS......................................5
         3.3.     NOTICE TO TRUSTEE...........................................6

4.       DEBT SECURITIES GUARANTEE............................................6

         4.1.     COVENANT TO PROVIDE DEBT SECURITIES GUARANTEE...............6
         4.2.     OPINIONS....................................................6
         4.3.     AUTOMATIC TERMINATION.......................................7

5.       GENERAL..............................................................7

         5.1.     INDENTURE SUPPLEMENTAL TO TRUST INDENTURE...................7
         5.2.     ACCEPTANCE OF TRUST.........................................7
         5.3.     COUNTERPARTS AND FORMAL DATE................................8

<PAGE>

THIS THIRD SUPPLEMENTAL INDENTURE (the "Supplemental Indenture") dated as of
March 11, 2002.

BETWEEN:

         NEXEN INC. (FORMERLY "CANADIAN OCCIDENTAL PETROLEUM LTD."), a
         corporation amalgamated under the Canada Business Corporations Act and
         having its head office in the City of Calgary, in the Province of
         Alberta (the "Corporation")

                                                               OF THE FIRST PART

                                     - and -

         CIBC MELLON TRUST COMPANY, a trust corporation incorporated under the
         laws of Canada, having an office in the City of Calgary, in the
         Province of Alberta (the "Trustee")

                                                              OF THE SECOND PART

         WITNESSETH THAT:

         WHEREAS in and by a trust indenture made as of April 28, 1998 (the
"Original Indenture") between the Corporation and the Trustee (the Original
Indenture, as amended and supplemented by the first supplemental indenture dated
as of April 28, 1998 (the "First Supplemental Indenture"), the second
supplemental indenture dated as of February 4, 1999 (the "Second Supplemental
Indenture") and this Supplemental Indenture and as the same may be further
amended or supplemented from time to time, being hereinafter called the "Trust
Indenture," which term includes any and every instrument supplemental or
ancillary thereto or in implementation thereof and the form and terms of any
particular series of Debt Securities (as defined below) established thereunder),
provision was made for the issue, in one or more series, by the Corporation of
debt securities of the Corporation (the "Debt Securities") in an unlimited
aggregate principal amount;

         AND WHEREAS the proper officers of the Corporation have duly authorized
the creation and issuance of a series of Debt Securities to be designated as
7.875% Notes due 2032 (the "Notes"), and to be limited (subject to the
exceptions described herein and in the Trust Indenture) to the aggregate
principal amount of U.S. $500,000,000, the further terms and conditions thereof
being hereinafter set forth, all in accordance with a resolution of the
directors of the Corporation;

         AND WHEREAS all necessary acts and proceedings have been done and taken
to authorize the execution of this Supplemental Indenture, to establish the
terms and form of the Notes pursuant to the Trust Indenture, and to make this
Supplemental Indenture and the said series of Notes, when executed and delivered
by the Corporation and certified and delivered by the Trustee as provided in the
Trust Indenture, legal, valid and binding upon the Corporation;

         AND WHEREAS the foregoing recitals are made as representations and
statements of fact by the Corporation and not by the Trustee;

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         NOW THEREFORE, it is hereby covenanted, agreed and declared as follows:

1.       INTERPRETATIONS AND AMENDMENTS

1.1.     SUPPLEMENTAL INDENTURE

         This "Supplemental Indenture", "hereto", "herein", "hereof", "hereby",
"hereunder" and similar expressions refer to this Supplemental Indenture and not
to any particular Article, Section or other portion hereof and include any and
every instrument supplemental or ancillary hereto or in implementation hereof,
and further include the terms of the Notes set forth in the form of Note annexed
as Schedule A hereto.

1.2.     DEFINITIONS IN TRUST INDENTURE

         All terms contained in this Supplemental Indenture which are defined in
the Original Indenture and not defined herein shall, for all purposes hereof,
have the meanings given to such terms in the Original Indenture unless the
context otherwise specifies or requires; provided, however, that notwithstanding
the foregoing, the terms "Corporation" and "Trustee" shall have the respective
meanings given to them in the Original Indenture.

1.3.     INTERPRETATION NOT AFFECTED BY HEADINGS

         The division of this Supplemental Indenture into Articles and Sections,
the provision of the table of contents hereto and the insertion of headings are
for convenience of reference only and shall not affect the construction or
interpretation of this Supplemental Indenture.

2.       NOTES

2.1.     FORM AND TERMS OF NOTES

         There shall be and is hereby created for issuance under the Trust
Indenture a series of Debt Securities which shall consist of and be limited
(subject to the exceptions set forth in Section 2.2(b) of the Original
Indenture) to the aggregate principal amount of U.S. $500,000,000 and shall be
designated as 7.875% Notes due 2032 (the "Notes"); provided, however, that if
the Corporation shall, at any time after the date hereof, increase the principal
amount of Notes which may be issued and issue such increased principal amount
(or any portion thereof), then any such additional Notes so issued shall have
the same form and terms (other than the date of issuance and the date from which
interest thereon shall begin to accrue and, under certain circumstances, the
first interest payment date), and shall carry the same right to receive accrued
and unpaid interest, as the Notes theretofore issued; and provided, further,
that, notwithstanding the foregoing, the Corporation shall not be entitled to
increase the principal amount of Notes which may be issued or issue any such
increased principal amount if the Corporation has effected satisfaction and
discharge of the Trust Indenture pursuant to Section 7.4 of the Original
Indenture or defeasance or covenant defeasance pursuant to Article 13 of the
Original Indenture.

         The Notes will mature, and the principal of the Notes and accrued and
unpaid interest thereon will be due and payable, on March 15, 2032, or such
earlier date as the principal of any of the Notes may become due and payable in
accordance with the provisions of the Trust Indenture.

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                                       -3-


         The Notes shall bear interest on the principal amount thereof from
March 11, 2002 or from the last date to which interest shall have been paid or
duly made available for payment on the Notes, whichever is later, at the rate of
7.875% per annum, payable semi-annually in arrears on March 15 and September 15
(each, an "Interest Payment Date") in each year, commencing September 15, 2002,
until the principal of and premium, if any, on the Notes is paid or duly made
available for payment; and should the Corporation at any time default in the
payment of any principal of, or premium, if any, or interest on the Notes when
due, the Corporation shall pay interest (such interest to be payable on demand),
to the extent permitted by law, on the amount in default at the same rate.
Interest on the Notes shall be computed on the basis of a 360-day year comprised
of twelve 30-day months. The interest payable, and punctually paid or duly
provided for, on any Interest Payment Date will, as provided in the Trust
Indenture, be paid to the Persons in whose names the Notes (or one or more
predecessor Notes) are registered at the close of business on the March 1 or
September 1 (the "Regular Record Dates"), as the case may be, immediately prior
to such Interest Payment Date, regardless of whether any such Regular Record
Date is a business day. Any such interest on the Notes not so punctually paid or
duly provided for on any Interest Payment Date shall be payable as provided in
the form of Note annexed hereto as Schedule A to this Supplemental Indenture.

         For the purposes only of the disclosure required by the INTEREST ACT
(Canada), and without affecting the amount of interest payable to any holder of
a Note or the calculation of interest on any Note, if the rate of interest on
any Note is calculated on the basis of a year (the "deemed year") which contains
fewer days than the actual number of days in the calendar year of calculation,
such rate of interest shall be expressed as a yearly rate for the purposes of
the INTEREST ACT (Canada) by multiplying such rate of interest by the actual
number of days in the calendar year of calculation and dividing it by the number
of days in the deemed year.

         All payments of principal of and premium, if any, and interest on the
Notes will be made in such coin or currency of the United States of America as
at the time of payment is legal tender for payment of public and private debts,
and all references herein to "United States dollars", "U.S. $" or "U.S. dollars"
shall be deemed to refer to such coin or currency of the United States of
America.

         The principal of and premium, if any, and interest on the Notes shall
be payable, and the Notes may be surrendered for exchange, registration,
transfer or discharge from registration, at the office or agency maintained by
the Corporation for such purpose from time to time in the City of Calgary,
Alberta (which shall initially be the office of the Trustee in the City of
Calgary, Alberta) and, under the circumstances described in Section 2.14(j) of
the Original Indenture, in the Borough of Manhattan, The City of New York, and
in such other places as the Corporation may from time to time designate. The
Trustee is hereby appointed as the initial Paying Agent, registrar and transfer
agent for the Notes in the City of Calgary, Alberta.

         The Notes shall be issued only as fully registered Notes, without
coupons, in denominations of U.S. $1,000 and integral multiples thereof. The
Notes initially will be represented by one or more Global Debt Securities
(collectively, the "Global Note") registered in the name of The Depository Trust
Company, as Depositary or its nominee, or a successor depositary or its nominee.

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                                       -4-


         The Notes and the certificate of the Trustee endorsed thereon shall be
substantially in the form set out in Schedule A to this Supplemental Indenture
with such appropriate insertions, omissions, substitutions and variations as the
Trustee may approve and shall be numbered in such manner as the Trustee may
approve, such approvals of the Trustee concerning any Note to be conclusively
evidenced by its certification of such Note.

         The register referred to in Section 3.2 of the Original Indenture
shall, with respect to the Notes, be kept at the office or agency in the City of
Calgary, Alberta that the Corporation may from time to time designate for such
purpose (which shall initially be the office of the Trustee in the City of
Calgary, Alberta), and at such other place or places as the Corporation with the
approval of the Trustee may hereafter designate. Without limitation to the
foregoing, if the Corporation shall at any time be required by the terms of the
Notes or the Trust Indenture to appoint a registrar for the Notes in the Borough
of Manhattan, The City of New York, the Corporation shall cause a register for
the Notes also to be kept at the office of the registrar in the Borough of
Manhattan, The City of New York and the Trustee hereby gives its approval to a
register being kept at such place.

         The Notes shall be subject to redemption at the option of the
Corporation as provided in Article 3 of this Supplemental Indenture. The
Corporation shall not be required to redeem, purchase or repay Notes pursuant to
any mandatory redemption, sinking fund or analogous provision or at the option
of the holders thereof. The Notes will not be convertible into or exchangeable
for securities of any Person. The Notes will be entitled to the benefit of Debt
Securities Guarantees upon the terms and conditions set forth in Article 4 of
this Supplemental Indenture.

         The Notes shall have the other terms and provisions set forth in the
form of Note attached hereto as Schedule A to this Supplemental Indenture, with
the same force and effect as if such terms and provisions were set forth in full
at this place.

2.2.     ISSUANCE OF NOTES

         Notes in the aggregate principal amount of U.S. $500,000,000 shall be
executed by the Corporation and delivered by it to the Trustee on the date of
issue for certification and delivery pursuant to and in accordance with the
provisions of Sections 2.4, 2.5 and 2.6 of the Original Indenture and, upon the
requirements of such provisions being complied with, the Notes shall be
certified by or on behalf of the Trustee and delivered by it to or upon the
written order of the Corporation without any further act or formality on the
part of the Corporation. The Trustee shall have no duty or responsibility with
respect to the use or application of any of the Notes so certified and delivered
or the proceeds thereof.

3.       REDEMPTION OF NOTES

3.1.     REDEMPTION OF NOTES

         The Notes will be redeemable at any time, in whole or from time to time
in part, at the option of the Corporation (in the manner and in accordance with
and subject to the terms and provisions set forth in the Trust Indenture), at a
redemption price equal to the greater of:

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                                       -5-


         (a)      100% of the principal amount of the Notes to be redeemed; and

         (b)      the sum of the present values of the remaining scheduled
                  payments of principal and interest thereon (exclusive of
                  interest accrued to the date of redemption) discounted to the
                  redemption date on a semi-annual basis (assuming a 360-day
                  year consisting of twelve 30-day months) at the Treasury Rate,
                  plus 37.5 basis points;

plus in each case accrued interest to the date of redemption; provided that
installments of interest on Notes which are due and payable on any date falling
on or prior to a redemption date will be payable to the registered holders of
such Notes (or one or more predecessor Notes), registered as such as of the
close of business on the relevant record dates.

3.2.     ADDITIONAL DEFINITIONS

         For the purposes of this Supplemental Indenture, the following
expressions shall have the following meanings:

"Treasury Rate" means, with respect to any redemption date, the rate per year
equal to the semiannual equivalent yield to maturity of the Comparable Treasury
Issue, assuming a price for the Comparable Treasury Issue (expressed as a
percentage of its principal amount) equal to the Comparable Treasury Price for
such redemption date;

"Comparable Treasury Issue" means the U.S. Treasury security selected by an
Independent Investment Banker as having a maturity comparable to the remaining
term of the Notes to be redeemed that would be utilized, at the time of
selection and in accordance with customary financial practice, in pricing new
issues of corporate debt securities of comparable maturity to the remaining term
of such Notes;

"Independent Investment Banker" means one of the Reference Dealers selected by
the Corporation;

"Comparable Treasury Price" means, with respect to any redemption date, (i) the
average of the bid and asked prices for the Comparable Treasury Issue (expressed
in each case as a percentage of its principal amount) on the third business day
preceding such redemption date, as set forth in the daily statistical release
(or any successor release) published by the Federal Reserve Bank of New York and
designated "Composite 3:30 p.m. Quotations for U.S. Government Securities" or
(ii) if such release (or any successor release) is not published or does not
contain such prices on such business day, (A) the average of the Reference
Treasury Dealer Quotations for such redemption date, after excluding the highest
and lowest such Reference Treasury Dealer Quotations, or (B) if the Corporation
is unable to obtain three such Reference Treasury Dealer Quotations, the average
of all such Quotations;

"Reference Treasury Dealer Quotations" means, with respect to each Reference
Dealer and any redemption date, the average, as determined by the Corporation,
of the bid and asked prices for the Comparable Treasury Issue (expressed in each
case as a percentage of its principal amount) quoted in writing to the
Corporation by such Reference Dealer at 5:00 p.m. (New York City time) on the
third business day preceding such redemption date; and

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                                       -6-


"Reference Dealer" means each of Banc of America Securities LLC and Deutsche
Banc Alex. Brown Inc. and their respective successors; provided, however, that
if any of the foregoing Reference Dealers shall cease to be a primary U.S.
Government securities dealer in New York City (a "Primary Treasury Dealer"), the
Corporation shall substitute therefor another Primary Treasury Dealer.

3.3.     NOTICE TO TRUSTEE

         The Corporation will provide notice to the Trustee prior to the
redemption date of the calculation of the redemption price.

4.       DEBT SECURITIES GUARANTEE

4.1.     COVENANT TO PROVIDE DEBT SECURITIES GUARANTEE

         The Corporation covenants and agrees that, so long as any of the Notes
remains outstanding: (a) if any Subsidiary of the Corporation shall at any time
guarantee (a "Subsidiary Guarantee") any Indebtedness of the Corporation
pursuant to Article 4 of the fourth supplemental indenture (the "Fourth
Supplemental Indenture") made as of the 2nd day of July, 1997 to the trust
indenture dated as of June 7, 1991 between the Corporation and CIBC Mellon Trust
Company, as successor trustee, then the Corporation will cause such Subsidiary
(a "Guarantor") to execute a Debt Securities Guarantee pursuant to which it will
guarantee the Debt Securities (including the Notes) on substantially the same
terms as are set forth in such Subsidiary Guarantee with such changes as may be
necessary to conform to local law or practice of the jurisdiction in which the
Guarantor is organized (which, in the case of a Subsidiary which is organized
and existing under the laws of any State of the United States or the District of
Columbia, may include a customary provision limiting amounts payable under such
Debt Securities Guarantee to such amount as will not violate applicable
fraudulent conveyance or other similar laws and a customary provision providing
for contribution from other Guarantors, if any) or as may be recommended by
independent legal counsel to the Trustee and incorporating provisions pursuant
to which the Guarantor shall submit to jurisdiction, waive immunity, and appoint
an agent for service of process to the same extent done by the Corporation
pursuant to the Trust Indenture; and (b) the Corporation will comply, and will
cause such Guarantor to comply, with all applicable securities laws and
regulations, including, without limitation, the Securities Act of 1933, the
Securities Exchange Act of 1934 and the Trust Indenture Act of 1939 (and in each
of the foregoing cases all applicable rules and regulations thereunder) and with
state securities and blue sky laws and regulations of the United States in
connection with any Debt Securities Guarantee. Any such Debt Securities
Guarantee shall be subject to the terms and provisions of the Trust Indenture,
including, without limitation, Article 12 of the Original Indenture. Any such
Debt Securities Guarantee shall be duly executed and delivered to the Trustee by
the applicable Guarantor, and shall be effective as of a date not later than 90
days after the date on which the Corporation becomes obligated to provide such
Subsidiary Guarantee.

4.2.     OPINIONS

         The Trustee will, at the expense of the Corporation, engage independent
legal counsel of recognized standing (in the jurisdiction in which the Guarantor
is organized) with respect to matters relating to publicly issued debt
securities to review the form of Debt Securities Guarantee, and both counsel to
the Corporation and such independent legal counsel shall deliver

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                                       -7-


legal opinions to the Trustee to the effect that such Debt Securities Guarantee
has been duly authorized, executed and delivered by, and is a valid, binding and
enforceable obligation of, the Guarantor (subject to customary exceptions). In
addition, the Trustee will, at the expense of the Corporation, engage
independent legal counsel of recognized standing with respect to matters of
United States federal securities laws (which, if possible, shall be the same
independent legal counsel referred to in the first sentence of this paragraph)
and such independent legal counsel shall deliver legal opinions to the Trustee
to the effect that such Debt Securities Guarantee has been registered under the
Securities Act of 1933 and that the Trust Indenture has been duly qualified
under the Trust Indenture Act of 1939 or that no such registration or
qualification is required. All such opinions shall be in form and substance
satisfactory to the Trustee, acting reasonably, and shall be delivered to the
Trustee not later than the time of delivery to the Trustee of the corresponding
Debt Securities Guarantee.

4.3.     AUTOMATIC TERMINATION

         In the event a Subsidiary Guarantee is discharged or released, then,
upon Written Order of the Corporation to the Trustee accompanied by a
Certificate of the Corporation confirming that the corresponding Subsidiary
Guarantee has been discharged or released, such Debt Securities Guarantee shall
automatically terminate and be released and the Trustee shall return to the
Corporation such Debt Securities Guarantee.

5.       GENERAL

5.1.     INDENTURE SUPPLEMENTAL TO TRUST INDENTURE

         This Supplemental Indenture is supplemental to the Original Indenture
and the Original Indenture, the First Supplemental Indenture and the Second
Supplemental Indenture shall, from this date forward, be read in conjunction
with this Supplemental Indenture. The Original Indenture, the First Supplemental
Indenture, the Second Supplemental Indenture and this Supplemental Indenture
shall, from this date forward, have effect so far as practicable as if all the
provisions of the Original Indenture, the First Supplemental Indenture, the
Second Supplemental Indenture and this Supplemental Indenture were contained in
one instrument.

5.2.     ACCEPTANCE OF TRUST

         The Trustee hereby accepts the trusts in this Supplemental Indenture
declared and provided for and agrees to perform the same upon the terms and
conditions herein before set forth in trust for the various Persons who shall
from time to time be Note holders subject to all the terms and conditions herein
set forth.

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                                       -8-


5.3.     COUNTERPARTS AND FORMAL DATE

         This Supplemental Indenture may be executed in several counterparts,
each of which so executed shall be deemed to be an original, and such
counterparts together shall constitute one and the same instrument and
notwithstanding their date of execution shall be deemed to bear the date first
above written.

         IN WITNESS WHEREOF the parties hereto have executed this Supplemental
Indenture under their respective corporate seals on the date first above
written.

                                    NEXEN INC.


                                    Per: /s/ Marvin F. Romanow
                                         --------------------------------------
                                         Name:  Marvin F. Romanow
                                         Title: Executive Vice President and
                                                Chief Financial Officer

                                                                          [Seal]


                                    Per: /s/ John B. McWilliams
                                         --------------------------------------
                                         Name:  John B. McWilliams
                                         Title: Senior Vice President, General
                                                Counsel and Secretary


                                    CIBC MELLON TRUST COMPANY


                                    Per: /s/ Roger Booth
                                         --------------------------------------
                                         Name:  Roger Booth
                                         Title: Asst. V. Pres.

                                                                          [Seal]


                                    Per: /s/ Robert Solis
                                         --------------------------------------
                                         Name:  Robert Solis
                                         Title: Account Manager

<PAGE>

                                   SCHEDULE A

to the Third Supplemental Indenture dated as of March 11, 2002 made between
Nexen Inc. (formerly Canadian Occidental Petroleum Ltd.) and CIBC Mellon Trust
Company, as Trustee.

                                  FORM OF NOTES

[INSERT IF THE NOTE IS A GLOBAL DEBT SECURITY: THIS NOTE IS A GLOBAL DEBT
SECURITY WITHIN THE MEANING OF THE TRUST INDENTURE HEREINAFTER REFERRED TO AND
IS REGISTERED IN THE NAME OF THE DEPOSITORY TRUST COMPANY (THE "DEPOSITARY",
WHICH TERM INCLUDES ANY SUCCESSOR DEPOSITARY FOR THE NOTES), A NEW YORK
CORPORATION, OR A NOMINEE THEREOF. THIS NOTE MAY NOT BE TRANSFERRED TO, OR
REGISTERED OR EXCHANGED FOR NOTES REGISTERED IN THE NAME OF, ANY PERSON OTHER
THAN THE DEPOSITARY OR A NOMINEE THEREOF, EXCEPT IN THE LIMITED CIRCUMSTANCES
DESCRIBED IN THE TRUST INDENTURE AND UNLESS AND UNTIL IT IS EXCHANGED FOR NOTES
IN DEFINITIVE CERTIFICATED FORM AS AFORESAID, MAY NOT BE TRANSFERRED EXCEPT AS A
WHOLE BY THE DEPOSITARY TO A NOMINEE OF THE DEPOSITARY OR BY A NOMINEE OF THE
DEPOSITARY TO THE DEPOSITARY OR ANOTHER NOMINEE OF THE DEPOSITARY OR BY THE
DEPOSITARY OR ITS NOMINEE TO A SUCCESSOR DEPOSITARY OR ITS NOMINEE.]


[INSERT IF THE NOTE IS A GLOBAL DEBT SECURITY: UNLESS THIS NOTE IS PRESENTED BY
AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY TO THE CORPORATION (AS DEFINED
BELOW) OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY
NOTE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO. OR IN SUCH OTHER NAME AS IS
REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITARY (AND ANY PAYMENT IS
MADE TO CEDE & CO. OR TO SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED
REPRESENTATIVE OF THE DEPOSITARY), ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR
VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL INASMUCH AS THE REGISTERED
OWNER HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.]

                                   NEXEN INC.

                  (FORMERLY CANADIAN OCCIDENTAL PETROLEUM LTD.)

                      (ORGANIZED UNDER THE LAWS OF CANADA)

                              7.875% NOTES DUE 2032

NO. O                                        Principal Amount: U.S. $500,000,000
CUSIP NO. O

FOR VALUE RECEIVED, NEXEN INC., a corporation organized under the laws of Canada
(hereinafter called the "Corporation", which term includes any successor
corporation under the Trust Indenture referred to below), for value received,
acknowledges itself indebted and hereby promises to pay to:

or registered assigns, on March 15, 2032 or on such earlier date as the
principal hereof may become due in accordance with the provisions of the Trust
Indenture hereinafter mentioned, the principal sum of O United States dollars
(U.S.$O) in immediately available funds, in lawful money of the United States of
America, and to pay interest on the principal amount hereof from March 11, 2002
or from the last date to which interest shall have been paid or duly made
available for payment on the Corporation's outstanding 7.875% Notes due 2032
(the "Notes"), whichever is later, at the rate of 7.875% per annum, payable
semiannually in arrears in like money, on March 15 and September 15 (each, an
"Interest Payment Date") in each year, commencing September 15, 2002, until the
principal hereof and premium, if any, hereon is paid or duly made available for
payment; and should the Corporation at any time default in the payment of any
principal of, or premium, if any, or interest on, this Note when due, to pay
interest (such interest to be payable on demand), to the

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extent permitted by law, on the amount in default at the same rate, in like
money. Interest on the Notes shall be computed on the basis of a 360-day year
comprised of twelve 30-day months. The interest payable, and punctually paid or
duly provided for, on any Interest Payment Date, will, as provided in such Trust
Indenture, be paid to the Person in whose name this Note (or one or more
predecessor Notes) is registered at the close of business on the March 1 or
September 1 (the "Regular Record Dates"), as the case may be, immediately prior
to such Interest Payment Date, regardless of whether any such Regular Record
Date is a business day. Any such interest on this Note not so punctually paid or
duly provided for on any Interest Payment Date will forthwith cease to be
payable to the holder on such Regular Record Date by virtue of having been such
holder and may either (i) upon (A) written notice by the Corporation to the
Trustee (as defined below) of the aggregate amount of defaulted interest
proposed to be paid by the Corporation and the date of such proposed payment and
(B) the concurrent deposit by the Corporation with the Trustee of U.S. dollars
in an amount equal to the aggregate amount proposed to be paid with respect to
such defaulted interest or upon such arrangements satisfactory to the Trustee
for such deposit of U.S. dollars in such amount on or prior to the date of such
proposed payment (such monies when so deposited to be held in trust for the
benefit of the Persons entitled thereto), be paid to the Person in whose name
this Note (or one or more predecessor Notes) is registered at the close of
business on a special record date for the payment of such defaulted interest to
be fixed by the Trustee (which special record date shall not be more than 15
days or less than 10 days prior to the date of the proposed payment and not less
than 10 days after the receipt by the Trustee of the aforesaid notice from the
Corporation), notice whereof shall be given to the holders of Notes not less
than 10 days prior to such special record date in the manner provided in the
Trust Indenture, or (ii) be paid at any time in any other lawful manner not
inconsistent with the requirements of any securities exchange on which the Notes
may be listed, and upon such notice as may be required by such exchange.

As interest on this Note becomes due (except interest payable at maturity or on
redemption which, so long as the date of such maturity or such redemption date
is not an Interest Payment Date, shall be paid upon presentation and surrender
of this Note for payment), the Corporation, either directly or through the
Trustee, shall send, at least five days prior to each date on which interest
becomes due, by prepaid ordinary mail, a cheque for such interest (less any tax
required to be withheld therefrom) payable to the order of the registered holder
of this Note at the close of business on the relevant Regular Record Date and
addressed to him at his last address appearing on the Note register, unless such
holder otherwise directs; provided that the Corporation may make any such
payment of interest (less any tax required to be withheld therefrom) by wire
transfer. In the case of joint holders, cheques shall, unless such joint holders
otherwise direct, be payable to the order of all such joint holders and, if more
than one address appears on the Note register in respect of a joint holding, any
cheque for interest shall be mailed to the first address so appearing. The
mailing of any such cheque or the making of any such payment by wire transfer
shall, to the extent of the sum represented thereby plus the amount of any tax
withheld as aforesaid, satisfy and discharge all liability for interest on this
Note, unless such cheque is not paid at par on presentation. Notwithstanding the
foregoing provisions of this paragraph or any other provision of the Notes or
the Trust Indenture, (i) so long as this Note is registered in the name of The
Depository Trust Company (or any successor Depositary for the Notes) or its
nominee (a "Global Note"), payments of principal of and premium, if any, and
interest on this Note shall be made by wire transfer of immediately available
funds unless otherwise required by such Depositary (ii) if definitive
certificated Notes are issued in exchange for interests in any Global Note, the
Corporation will pay the principal of and premium, if any, and interest on such
definitive certificated Notes by wire

<PAGE>
                                       -3-


transfer of immediately available funds (provided that the holders thereof shall
have provided appropriate wire transfer instructions to the Corporation); and
(iii) if definitive certificated Notes are issued in exchange for interests in
any Global Note or if the Depositary for the Notes shall so require, the
Corporation will maintain a Paying Agent, registrar and transfer agent for the
Notes in the Borough of Manhattan, The City of New York.

All payments of the principal of and premium, if any, and interest on this Note
will be made in such coin or currency of the United States of America as of the
time of payment is legal tender for payment of public and private debts, and all
references herein to "United States dollars", "U.S. $" or "U.S. dollars" shall
be deemed to refer to such coin or currency of the United States of America.

This Note is one of the duly authorized series of Debt Securities of the
Corporation (herein called the Notes) issued under and entitled to the benefits
of a trust indenture made as of April 28, 1998, as supplemented by the first
supplemental indenture thereto made as of April 28, 1998, by the second
supplemental indenture thereto made as of February 4, 1999 and by the third
supplemental indenture thereto made as of March 11, 2002, each between the
Corporation and CIBC Mellon Trust Company, as trustee (the "Trustee", which term
includes any successor trustee under the Trust Indenture) (such trust indenture,
first supplemental trust indenture and second supplemental indenture, as the
same may be further amended or supplemented from time to time, are herein called
collectively the "Trust Indenture"). Reference is hereby made to the Trust
Indenture for a description of the terms and conditions upon which the Notes are
issued or may be issued and held and the rights of the holders of Notes issued
and to be issued thereunder and of the Corporation and of the Trustee, all to
the same effect as if the provisions of the Trust Indenture were herein set
forth, to all of which provisions the holder of this Note by acceptance hereof
assents. This Note is one of the series designated on the face hereof, limited
(subject to exceptions provided in the Trust Indenture) in aggregate principal
amount to U.S. $500,000,000 subject to the right of the Corporation, on the
terms and subject to the conditions set forth in the Trust Indenture, at any
time or from time to time to increase the principal amount of such series and to
issue such increased principal amount of Notes (or any portion thereof). All
terms used in this Note which are defined in the Trust Indenture and not defined
herein shall have the meanings assigned to them in the Trust Indenture.

This Note is a direct obligation of the Corporation.

This Note is redeemable at any time, in whole or from time to time in part, at
the option of the Corporation, upon the terms and subject to the conditions set
forth in the Trust Indenture, at a redemption price equal to the greater of (i)
100% of the principal amount of this Note to be redeemed and (ii) the sum of the
present values of the remaining scheduled payments of principal and interest
hereon (exclusive of interest accrued to the date of redemption) discounted to
the redemption date on a semiannual basis (assuming a 360-day year consisting of
twelve 30-day months) at the Treasury Rate, plus 37.5 basis points, plus in each
case accrued interest to the date of redemption (provided that installments of
interest which are due and payable on any date falling on or prior to a
redemption date will be payable to the registered holder of this Note (or one or
more predecessor Notes), registered as such as of the close of business on the
relevant record date), all as more fully provided in the Trust Indenture.

This Note will not be entitled to the benefit of a sinking fund.

<PAGE>
                                       -4-


If an Event of Default with respect to the Notes shall occur and be continuing,
the principal of and interest on the Notes may be declared due and payable in
the manner and with the effect provided in the Trust Indenture.

This Note is subject to the provisions in the Trust Indenture on defeasance and
covenant defeasance.

The Trust Indenture contains provisions for holding meetings of holders of Notes
and, subject to certain exceptions, for making binding upon all holders of Notes
extraordinary resolutions passed at such meetings in accordance with such
provisions and instruments in writing signed by the holders of a specified
percentage in principal amount of the Debt Securities outstanding.

No reference herein to the Trust Indenture and no provision of this Note shall
alter or impair the obligation of the Corporation, which is absolute and
unconditional, to pay the principal of, and premium, if any, and interest on,
this Note at the times, place and rate, and in the currency, herein and in the
Trust Indenture prescribed.

No transfer of this Note shall be valid unless made on the registers to be kept
at the office of the Trustee in the City of Calgary, Alberta and at such other
place or places (if any) as the Corporation may designate, by the registered
holder or his executors or administrators or other legal representatives or his
or their attorney duly appointed by an instrument in writing in form and
execution satisfactory to the Trustee or other registrar, and upon compliance
with such reasonable requirements as the Trustee or other registrar may
prescribe and thereupon one or more new Notes, of authorized denominations and
for the same aggregate principal amount, will be issued to the designated
transferee or transferees. The Person in whose name this Note shall be
registered shall be deemed and regarded as the owner hereof for all purposes of
the Trust Indenture and payment of or on account of the principal hereof and
premium, if any, and interest hereon shall be made only to or upon the order of
such registered holder.

As provided in the Trust Indenture and subject to certain limitations set forth
therein, the Notes are exchangeable for a like aggregate principal amount of
Notes of authorized denominations as requested by the holders surrendering the
same. No service charge will be made for any exchange, registration, transfer or
discharge from registration of any Note, although the Corporation and the
Trustee may require payment of a sum sufficient to cover any transfer tax or
other similar governmental charge payable in connection therewith. This Note may
be surrendered for registration of transfer, exchange and payment at the office
of the Trustee in the City of Calgary, Alberta and, if so required pursuant to
the Trust Indenture and the Notes, at the office or agency maintained by the
Corporation for that purpose in the Borough of Manhattan, The City of New York.

The Notes are issuable only in registered form without coupons in denominations
of U.S. $1,000 and integral multiples of U.S. $1,000.

The Trust Indenture requires that the Corporation comply with certain
restrictive covenants set forth therein and provides that, under certain
circumstances, one or more subsidiaries of the Corporation may be required to
guarantee the Notes. Reference is made to the Trust Indenture for a further
description of all such terms and provisions.

<PAGE>
                                       -5-


This Note shall be governed by and construed in accordance with the laws of the
Province of Alberta and the federal laws of Canada applicable therein and, to
the extent provided in the Trust Indenture, by the TRUST INDENTURE ACT of 1939,
as amended. This Note shall not become obligatory for any purpose until it shall
have been certified by the Trustee for the time being under the Trust Indenture.

IN WITNESS WHEREOF NEXEN INC. has caused this Note to be sealed with its
corporate seal and to be signed by its duly appointed and authorized officers
this ___ day of ______________.

                                    NEXEN INC.


                                    Per: ______________________________________
                                    Name:
                                    Title:

                                                                          [Seal]


                                    Per: ______________________________________
                                    Name:
                                    Title:



                                    This is one of the Notes referred to
                                    in the Trust Indenture within mentioned


                                    CIBC MELLON TRUST COMPANY, TRUSTEE

                                    Per: ______________________________________
                                         Authorized Officer

                                                                          [Seal]


                                    Date of Certification:_____________________

<PAGE>

                                  ABBREVIATIONS

         The following abbreviations, when used in the inscription on the face
of this instrument, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM - as tenants in common          UNIF GIFT MIN ACT -______ Custodian_____
TEN ENT - as tenants by the entireties                     (Cust)        (Minor)
JT TEN - as joint tenants with right of survivorship     Under Uniform Gifts to
and not as tenants in common                             Minors Act_____________
                                                                     (State)

     Additional abbreviations may also be used though not in the above list.

                   ___________________________________________

FOR VALUE RECEIVED, the undersigned registered holder hereby sell(s), assign(s)
and transfer(s) unto


PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE

_________________________________________________________

_________________________________________________________


________________________________________________________________________________
             PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS OF ASSIGNEE


________________________________________________________________________________
the within Note and all rights thereunder, hereby irrevocably constituting and
appointing


_______________________________________________________________________Attorney
to transfer said Note on the books of the Corporation with full power of
substitution in the premises.

Dated:__________________________________________________________________________

         Notice: The signature to this assignment must correspond with the name
as it appears upon the face of the within Note in every particular, without
alteration or enlargement or any change whatever.