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                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549


                                    FORM 11-K


      (Mark One)

                [X]   ANNUAL REPORT PURSUANT TO SECTION 15(d)
                      OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE FISCAL YEAR ENDED DECEMBER 31, 2005

                                       OR

                [_]   TRANSITION REPORT PURSUANT TO SECTION 15(d)
                      OF THE SECURITIES EXCHANGE ACT OF 1934

FOR THE TRANSITION PERIOD FROM __________ TO __________


                          COMMISSION FILE NO. 001-06702


         A.     Full title of the plan and address of the plan, if different
from that of the issuer named below:

                               NEXEN SAVINGS PLAN
                          12790 Merit Drive, Suite 800
                            Dallas, Texas 75251-1270


         B.     Name of issuer of the securities held pursuant to the plan and
the address of its principal executive office:

                                   NEXEN INC.
                              801 - 7th Avenue SW
                       Calgary, Alberta, Canada T2P 3P7


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NEXEN SAVINGS PLAN
FINANCIAL STATEMENTS AND SUPPLEMENTAL SCHEDULE
- -------------------------------------------------------------------------------

DECEMBER 31, 2005










                                TABLE OF CONTENTS


REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM                      1


FINANCIAL STATEMENTS

     Statements of Net Assets Available for Benefits                         2

     Statements of Changes in Net Assets Available for Benefits              3

     Notes to Financial Statements                                           4


SUPPLEMENTAL SCHEDULE *

     Schedule H, line 4i - Schedule of Assets (Held at End of Year)          9



     *  Other schedules required by 29 CFR 2520.103-10 of the Department of
        Labor's Rules and Regulations for Reporting and Disclosure under
        Employee Retirement Income Security Act of 1974 have been omitted
        because they are not applicable.




            REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM



To the Administrative Committee
NEXEN SAVINGS PLAN
Dallas, Texas


We have  audited  the  accompanying  statements  of net  assets  available  for
benefits of the Nexen  Savings  Plan (the  "Plan") as of December  31, 2005 and
2004,  and the  related  statements  of  changes in net  assets  available  for
benefits  for  the  years  then  ended.  These  financial  statements  and  the
supplemental  schedule  referred to below are the  responsibility of the Plan's
Administrative  Committee. Our responsibility is to express an opinion on these
financial statements and schedule based on our audits.

We conducted our audits in accordance  with the standards of the Public Company
Accounting  Oversight Board (United  States).  Those standards  require that we
plan and perform the audits to obtain  reasonable  assurance  about whether the
financial  statements  are free of  material  misstatement.  An audit  includes
examining,  on a test basis, evidence supporting the amounts and disclosures in
the  financial  statements.  An audit also includes  assessing  the  accounting
principles  used  and  significant  estimates  made by  management,  as well as
evaluating the overall financial  statement  presentation.  We believe that our
audits provide a reasonable basis for our opinion.

In our opinion,  the financial  statements referred to above present fairly, in
all  material  respects,  the net assets  available  for  benefits of the Nexen
Savings  Plan as of  December  31,  2005 and 2004,  and the  changes in its net
assets  available  for benefits for the years then ended,  in  conformity  with
accounting principles generally accepted in the United States of America.

Our audits  were  performed  for the purpose of forming an opinion on the basic
financial  statements  taken as a whole.  The  supplemental  schedule of assets
(held at end of year) is presented for purposes of  additional  analysis and is
not a required  part of the basic  financial  statements  but is  supplementary
information  required by the  Department of Labor's Rules and  Regulations  for
Reporting and Disclosure under the Employee  Retirement  Income Security Act of
1974. The supplemental  schedule has been subjected to the auditing  procedures
applied in the audit of the basic financial  statements and, in our opinion, is
fairly  stated in all  material  respects in  relation  to the basic  financial
statements taken as a whole.




WEAVER AND TIDWELL, L.L.P.

Dallas, Texas
June 8, 2006




                               NEXEN SAVINGS PLAN
                STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS
                           DECEMBER 31, 2005 AND 2004


                                                         2005          2004
                                                     -----------    -----------
ASSETS

     Cash                                            $       352    $     2,927
     Investments, at fair value                       45,552,975     32,693,915
     Receivables for securities sold                                    181,533
     Participant contributions receivable                  1,439
     Accrued dividends receivable                         13,558         12,210
     Participant loans                                   969,883        941,365
                                                     -----------    -----------


           TOTAL ASSETS                               46,538,207     33,831,950
                                                     -----------    -----------


LIABILITIES

     Payables for securities purchased                                  184,015
     Other payables                                            5            224
                                                     -----------    -----------

           TOTAL LIABILITIES                                   5        184,239
                                                     -----------    -----------


NET ASSETS AVAILABLE FOR BENEFITS                    $46,538,202    $33,647,711
                                                     ===========    ===========


The Notes to Financial Statements are
  an integral part of these statements

                                       2


                               NEXEN SAVINGS PLAN
           STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS
                     YEARS ENDED DECEMBER 31, 2005 AND 2004



                                                               2005          2004
                                                          -----------    -----------
                                                                   
ADDITIONS

     Investment income:
         Net appreciation in fair value of investments    $ 9,946,256    $ 2,982,992
         Interest                                             271,859        231,387
         Dividends                                          1,369,008        572,298
                                                          -----------    -----------

                                                           11,587,123      3,786,677
                                                          -----------    -----------

     Contributions:
         Participants                                       1,980,100      1,752,603
         Employer                                           1,193,594      1,108,541
         Rollover                                              47,204        296,621
                                                          -----------    -----------

                                                            3,220,898      3,157,765
                                                          -----------    -----------


         TOTAL ADDITIONS                                   14,808,021      6,944,442
                                                           -----------    -----------


DEDUCTIONS

     Benefits paid to participants                          1,912,767        971,453
     Administrative expenses                                    4,763          5,337
                                                          -----------    -----------


         TOTAL DEDUCTIONS                                   1,917,530        976,790
                                                          -----------    -----------

NET INCREASE IN NET ASSETS AVAILABLE                       12,890,491      5,967,652

NET ASSETS AVAILABLE FOR BENEFITS
         Beginning of year                                 33,647,711     27,680,059
                                                          -----------    -----------

NET ASSETS AVAILABLE FOR BENEFITS
         End of year                                      $46,538,202    $33,647,711
                                                          ===========    ===========


The Notes to Financial Statements are
  an integral part of these statements

                                       3


                               NEXEN SAVINGS PLAN
                          NOTES TO FINANCIAL STATEMENTS


Note 1.       Description of the Plan

     The  following  description  of the Nexen  Savings  Plan (the  "Plan")  is
     provided for general information  purposes only. More complete information
     regarding the Plan's provisions may be found in the Plan Document.

     The Plan is a defined  contribution  plan that was  adopted  September  1,
     1988,  and  amended and  restated  effective  January 1, 2002,  to provide
     eligible  employees of Nexen  Petroleum  U.S.A.  Inc. (the  "Company") and
     participating  employers,  Nexen Chemicals  U.S.A.  Inc.,  Nexen Marketing
     U.S.A.   Inc.,  Nexen  Oil  and  Gas  U.S.A.  Inc.,  and  Nexen  Petroleum
     International (U.S.A.) Inc. (the "Participating Employers"),  wholly owned
     subsidiaries  of Nexen Inc., and Canexus U.S. Inc., a method to meet their
     long-range  financial  objectives under the requirements of Section 401(k)
     of the Internal Revenue Code.

     For the years ended December 31, 2005 and 2004,  Nationwide Trust Company,
     FSB (the "Trustee") was the Plan Trustee with the  recordkeeping  function
     performed by The 401(k) Company (the "Recordkeeper").

     All regular employees of the Company and  Participating  Employers who are
     18 years of age and over are  eligible to  participate  in the Plan on the
     entry date coinciding with or next following the date the employee attains
     age 18.  Participant  contributions  are  made on a  voluntary  basis  and
     directly withheld from the participant's eligible compensation, as defined
     in the Plan  Document.  Contributions  may be made  with  pretax  dollars,
     after-tax  dollars,  or a  combination  of pretax and  after-tax  dollars.
     Eligible  compensation  excludes  overtime and bonuses.  Participants  are
     immediately  vested in their  employee  contribution  account  and  actual
     earnings thereon.

     The  Company  and  Participating  Employers  will  match  100  percent  of
     Participant   contributions  up  to  6%  of  the  Participant's   eligible
     compensation. In addition, a Participant who completes one hour of service
     after  January  1,  2000,  shall  be  vested  100% in his or her  employer
     matching account.

     The Plan's  investment  options are: (1) Stable Value Trust Fund, (2) Bond
     Fund of America A, (3) Delaware Group:  REIT Fund A, (4) Managers  Special
     Equity Fund, (5) Scudder Equity 500 Index Fund, (6) Growth Fund of America
     A, (7) First Eagle  Overseas  Fund A, (8)  EuroPacific  Growth Fund A, (9)
     Washington  Mutual Investors Fund A, (10) Oppenheimer  Developing  Markets
     Fund A, (11) Third Avenue Value Fund, (12) American Beacon Small Cap Value
     Plan,  and (13) Nexen Inc.  Stock  Fund.  All  Company  and  Participating
     Employers  contributions  are invested in accordance  with the  investment
     choices selected by each respective Participant.

     Distribution of a Participant's  entire account becomes due in three ways:
     (1) upon  termination  of employment,  (2) death,  or (3)  disability,  as
     defined  in the  Plan  Document.  At the  option  of  the  Participant  or
     beneficiary,  such  account  balances  may be  distributed  in a  lump-sum
     payment or via  periodic  installment  payments as  described  in the Plan
     Document.  Withdrawals from the Plan by active  Participants are permitted
     for specific  instances of financial  hardship and age 59 1/2 withdrawals,
     which can be made once every six months. Once per Plan year, a Participant
     may  withdraw  a  portion  or all of his  or her  after-tax  and  rollover
     account, subject to a $250 minimum.

     In  December  2005,  the  Financial   Accounting  Standards  Board  issued
     Statement of Position (SOP) 94-4-1, "REPORTING OF FULLY BENEFIT-RESPONSIVE
     INVESTMENT  CONTRACTS HELD BY CERTAIN INVESTMENT  COMPANIES SUBJECT TO THE
     AICPA INVESTMENT COMPANY GUIDE AND DEFINED-CONTRIBUTION HEALTH AND WELFARE
     AND PENSION PLANS," which affects defined  contribution  pension plans and
     health and  welfare  plans that hold fully  benefit-responsive  investment
     contracts.  Presently,  the  Plan  has no  investment  contracts  that are
     considered fully benefit-responsive for purposes of SOP 94-4-1



                                        4


                               NEXEN SAVINGS PLAN
                          NOTES TO FINANCIAL STATEMENTS



Note 2.       Summary of Significant Accounting Policies

  Use of Estimates

     The  preparation  of financial  statements in conformity  with  accounting
     principles  generally accepted in the United States requires management to
     make  estimates and  assumptions  that affect the reported  amounts of net
     assets  available for benefits and  disclosure  of  contingent  assets and
     liabilities  at the  date of the  financial  statements  and the  reported
     amounts of  additions  to and  deductions  from net assets  available  for
     benefits  during the reporting  period.  Actual  results could differ from
     those estimates.

  Basis of Accounting

     The financial statements of the Plan are presented on the accrual basis of
     accounting in accordance with accounting  principles generally accepted in
     the United States of America.  Current year contributions,  expenses,  and
     investment  income,  including both interest and dividends,  which are not
     received  or paid until the  subsequent  year,  are accrued in the current
     year. Benefits are recorded when paid.

  Investments

     Investments  are stated at fair value as  determined by the Trust based on
     quoted  market  prices  at the  Plan's  year end.  Purchases  and sales of
     investments  are recorded on a trade date basis.  Participants  may direct
     their  contributions  and any  related  earnings  into  thirteen  distinct
     investment  options,  including  the Nexen Inc.  Stock  Fund.  Interest is
     allocated to  Participant  accounts on a pro-rata  basis  depending on the
     Participants' account balance. Dividends are allocated based on the number
     of shares in a Participant's account.

     A brief description of each investment option is as follows:

     STABLE VALUE TRUST FUND - The Stable  Value Trust  Fund's core  investment
     vehicle is the AMVESCAP  National  Trust Company  Stable Value Trust Fund.
     The  remaining  portion of the money is  invested  in money  market  funds
     offered  through the following  mutual fund  families:  The American Funds
     Group,  Oppenheimer Funds,  Managers Funds,  Third Avenue Funds,  Delaware
     Funds, First Eagle Funds, and Scudder Funds.

     AMERICAN  BEACON  SMALL CAP VALUE PLAN - is a small  value fund that seeks
     long-term capital appreciation and current income by investing over 80% of
     its assets in equity securities of companies within the United States.

     BOND   FUND  OF   AMERICA   A  -  invests   primarily   in  high   quality
     intermediate-term corporate bonds and U.S. government securities.

     DELAWARE  GROUP:  REIT  FUND  A - is a  non-diversified  fund  that  seeks
     long-term  total return by investing  primarily in equities of real-estate
     investment trusts (REITs).

     MANAGERS SPECIAL EQUITY FUND - is a small growth fund that seeks long-term
     capital  appreciation  by  investing  at least  80% of  assets  in  equity
     securities.

     SCUDDER  EQUITY 500 INDEX FUND - is a large company growth and income fund
     that invests primarily in equity securities of companies included in the S
     & P 500.



                                        5


                               NEXEN SAVINGS PLAN
                         NOTES TO FINANCIAL STATEMENTS



Note 2.       Summary of Significant Accounting Policies - continued

  Investments - continued

     GROWTH  FUND OF  AMERICA A - is a large  growth  fund that  seeks  capital
     growth by investing  primarily in common stocks. The fund may invest up to
     15% of assets in  securities  of issuers  domiciled  outside of the United
     States and Canada.

     FIRST EAGLE OVERSEAS FUND A - is a foreign stock fund that seeks long-term
     capital growth by investing  primarily in equities of small- and mid-sized
     foreign companies in developed and emerging markets.

     EUROPACIFIC  GROWTH FUND A - is a large  company  foreign  stock fund that
     seeks long-term capital  appreciation by investing in companies  domiciled
     in developed countries outside the United States.

     WASHINGTON  MUTUAL  INVESTORS  FUND A - is a large company  value-oriented
     growth and income fund.

     OPPENHEIMER  DEVELOPING MARKETS FUND A - is an emerging markets stock fund
     that seeks  long-term  growth by investing in stock of issues in countries
     with developing markets.

     THIRD  AVENUE  VALUE FUND - is a small  value  fund that  seeks  long-term
     capital appreciation by investing in equity securities issued by companies
     that are believed to be undervalued and to have strong financial positions
     and responsible management.

     NEXEN INC. STOCK FUND - provides  ownership  interest in Nexen Inc. Common
     Stock with short-term  cash sufficient to maintain a liquidity  balance to
     facilitate daily transactions and compliance with securities law.

  Market and Credit Risks

     The Plan invests in a variety of  investments.  Investments are exposed to
     various risks,  such as interest rate, market and credit risks. Due to the
     level  of  risk  associated  with  certain  investments,  it is  at  least
     reasonably possible that the changes in the values of the investments will
     occur in the near term and that such changes could  materially  affect the
     amount  reported  in the  Plan's  statement  of net assets  available  for
     benefits.

  Administration

     The  Plan  is  administered  by the  Administrative  Committee,  which  is
     composed of members who are either  officers or  employees of the Company.
     Investment  options for the Plan are  selected by the Benefit  Plan Design
     Committee from funds available through the Recordkeeper.  Some of the fund
     providers  charge 12b-1 fees at the fund level before earnings are paid to
     investors.  The Recordkeeper  receives fees from these fund providers from
     12b-1 fees charged to the funds.  12b-1 fees received by the  Recordkeeper
     are based on Plan  assets  invested in each fund.  Similarly,  all Trustee
     fees for the Plan are received from 12b-1 fees charged to the funds. 12b-1
     fees  received by the  Trustee  are also based on Plan assets  invested in
     each fund.


                                        6


                               NEXEN SAVINGS PLAN
                         NOTES TO FINANCIAL STATEMENTS



Note 2.       Summary of Significant Accounting Policies - continued

  Loans to Participants

     Participant  loans receivable are stated at cost, which  approximates fair
     value.  A  Participant  may  borrow up to the  lesser of 50% of his or her
     vested  account  balance or $50,000  with a minimum loan amount of $1,000.
     Loans are repayable through payroll  deductions over periods ranging up to
     60  months.  Participants  are  charged  a $50 loan  set-up  fee with a $2
     monthly  maintenance  fee per loan. The loans are secured by a lien on the
     borrower's  vested account  balance in the Plan and bear interest at rates
     based on prevailing market conditions. Interest rates on outstanding loans
     at December 31, 2005 ranged from 5.76% to 9.25%.

  Plan Termination

     Although it has not  expressed any intention to do so, the Company has the
     right to terminate the Plan  pursuant to provisions  set forth by the Plan
     Document  and  subject to the  provisions  of ERISA.  In the event of Plan
     termination,  each  Participant's  account  shall  become fully vested and
     Participants will be entitled to distributions of their entire accounts.


Note 3.       Tax Status

     The Plan  received a  favorable  determination  letter  from the  Internal
     Revenue  Service  dated  April  5,  2002,  stating  that  the Plan and its
     amendments are qualified under Section 401(a) of the Internal Revenue Code
     of 1986,  as amended (the  "Code"),  and the Trust is exempt from taxation
     under Section 501(a) of the Code. The Trust  established under the Plan to
     hold the Plan's assets is intended to qualify  pursuant to the appropriate
     section of the Internal  Revenue Code as a  tax-exempt  organization.  The
     plan has been amended since receiving the determination  letter.  However,
     the Company and the Plan's tax counsel believe that the Trust continues to
     qualify and to operate as designed.


Note 4.       Investments

     Investments that represent 5% or more of the net assets available for Plan
     benefits at December 31, 2005 and 2004 are as follows:


                                                December 31,     December 31,
                                                    2005             2004
                                                 Fair Value       Fair Value
                                                ------------     ------------
     Bond Fund of America A                     $  3,150,948     $  2,459,382
     EuroPacrfic Growth Fund A                     2,755,028        2,213,910
     Nexen Inc. Stock Fund                        15,072,085        6,934,421
     Stable Value Fund                             5,501,169        5,097,765
     Third Avenue Value Fund                       2,518,717        1,993,099
     Washington Mutual Investors Fund A            4,399,742        4,092,367
     Growth Fund of America A                      2,608,119
     Delaware Group REIT Fund A                                     1,722,598
     MFS Massachusetss Investors Growth Fund A                      2,097,425


                                        7


                               NEXEN SAVINGS PLAN
                          NOTES TO FINANCIAL STATEMENTS



Note 4.       Investments - continued

     During 2005 and 2004, the Plan's  investments  (including gains and losses
     on investments bought and sold, as well as held during the year) increased
     in value by $11,587,123 and $3,786,677, respectively, as follows:



                                       2005                           2004
                            ----------------------------   --------------------------
                                            Realized and                 Realized and
                            Interest and     Unrealized    Interest and   Unrealized
                              Dividends        Gains         Dividends       Gains
                            ------------   -------------   ------------  ------------
                                                             
      Mutual funds          $ 1,519,930    $  1,015,736    $  688,502    $  2,002,637
      Stock funds                53,924       8,930,520        55,876        980,355
      Loans to Participants      67,013                        59,307


Note 5.       Plan Amendments

     On March 8,  2005,  the  Fifth  Amendment  to the Nexen  Savings  Plan was
     executed  and  adopted  effective  March 28,  2005.  The  purpose  of this
     amendment was to change the Plan's cash-out distribution dollar limit from
     $5,000 to $1,000.

     On August 17,  2005,  the Sixth  Amendment  to the Nexen  Savings Plan was
     executed  and  adopted.  Effective  August 18,  2005,  Section XIII of the
     Adoption Agreement was amended to add Canexus U.S. Inc. as a Participating
     Employer covered under the Plan.



                                        8





                              SUPPLEMENTAL SCHEDULE







                               NEXEN SAVINGS PLAN
         Schedule H, Line 4i - SCHEDULE OF ASSETS (HELD AT END OF YEAR)
                                EIN: 06-0944810
                                PLAN NUMBER 001
                               December 31, 2005




(a)                  (b)                                       (c)                        (d)          (e)
                                                Description of Investment including
          Identity of Issuer, borrower          maturity date, rate of investment,                   Current
            lessor, or similar party             collateral, par, or maturity value      Cost #       value
- -------- -------------------------------  -------------------------------------------  ---------  ------------
                                                                                         
PARTICIPANT-DIRECTED INVESTMENTS:

         The American Funds Group         Bond Fund of America A,
                                            Net Asset Value $13.22                                $  3,150,948

         The American Funds Group         Washington Mutual Investors Fund A,
                                            Net Asset Value $30.84                                   4,399,742

         The American Funds Group         EuroPacific Growth Fund A,
                                            Net Asset Value $41.10                                   2,755,028

         American Beacon                  American Beacon Small Cap Value Plan
                                            Net Asset Value $20.03                                     845,029

         Scudder Funds                    Scudder Equity 500 Index Fund,
                                            Net Asset Value $139.85                                  1,884,097

         First Eagle Funds                First Eagle Overseas Fund A,
                                            Net Asset Value $23.04                                   1,323,872

         Managers Funds                   Managers Special Equity Fund
                                            Net Asset Value $86.77                                   1,597,513

         The American Funds Group         Growth Fund of America A,
                                            Net Asset Value $30.86                                   2,608,119

         Third Avenue Funds               Third Avenue Value Fund,
                                            Net Asset Value $54.78                                   2,518,717

         Delaware Funds                   Delaware Group: REIT Fund A,
                                            Net Asset Value $19.18                                   2,121,991

         Oppenheimer Funds                Oppenheimer Developing Markets Fund A,
                                            Net Asset Value $36.33                                   1,364,984

         The American Funds Group         Cash Management Trust Of America,
                                            Par Value $1.00                                            409,681

         AMVESCAP National Trust Company  Stable Value Trust Fund,
                                            Par Value $1.00                                          5,501,169

         AllianceBernstein                Capital Reserve Money Market Fund
                                            Par Value $1.00                                                115

         Chase Bank, NA                   Cash                                                             237

   *     Nexen Inc.                       Nexen Inc. Stock Fund
                                             (Nexen Inc. Stock, no par,
                                              Net Asset Value $47.63)                               15,072,085

   *     Loans to Participants            Interest Rates From 5.76% to 9.25%                           969,883
                                                                                                   ------------

                                                                                                  $ 46,523,210
                                                                                                   ============


  *  Indicates each identified person/entity known to be party-in-interest.

  #  Historical cost information omitted as it is not required for
     participant-directed investments.


     This  supplemental  schedule lists assets held for investment  purposes at
     December  31, 2005,  as required by the  Department  of Labor's  Rules and
     Regulations for Reporting and Disclosure.

                                       9




                                   SIGNATURES

     THE PLAN.  Pursuant to the requirements of the Securities  Exchange Act of
1934,  Nexen  Petroleum  U.S.A.  Inc. has duly caused this annual  report to be
signed on its behalf by the undersigned hereunto duly authorized.

DATED:  June 28, 2006

                                       NEXEN SAVINGS PLAN

                                       By:  Nexen Petroleum U.S.A. Inc.


                                       By:  /s/ Douglas B. Otten
                                            ----------------------------
                                            Douglas B. Otten, President








                               INDEX TO EXHIBITS


        EXHIBIT
        NUMBER                   DESCRIPTION OF EXHIBITS
        -------                  -----------------------

           1               Consent of Weaver & Tidwell, L.L.P.