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                                                                   EXHIBIT 10.43

                                    ADVICE

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<S>                                                          <C>
TO:         Distribution                                     FROM:       C.R. Harden
                                                                         HMB 3432

SUBJECT:    ARCO/Vastar Agreement - Sale of Vastar Building  DATE:       September 15, 1999
            effective September 15, 1999                     CROSS REF:  Lease Agreement
            Lease by and between Lexington Memorial                 dated January 1, 1994, and
            L.L.C., as Landlord, and                                Property Management
            Vastar Resources, Inc., as Tenant                       Services Agreement dated
                                                                    effective January 1, 1994
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                ARCO/Vastar Agreement - Sale of Vastar Building

1.   Upon closing of the sale of the HMB Building, between ARCO and Lexington
     Memorial L. L. C. (Lexington), ARCO and Vastar shall execute an agreement
     terminating the Lease Agreement dated January 1, 1994, as amended (Existing
     Lease) covering the premises and building located at 15375 Memorial Drive,
     Houston, Texas 77079 and the Property Management Services Agreement
     (Management Agreement) dated effective January 1, 1994.

2.   Upon closing as stated above, Vastar will execute a new lease agreement
     with Lexington for a term of 10 years, attached as Exhibit "A". This lease
     is also adviced hereinbelow.

3.   Vastar will also execute an estoppel certificate, attached as Exhibit "B".

4.   All amounts owed between Vastar and ARCO under existing agreements shall be
     prorated as of their termination dates.

5.   At closing, ARCO shall pay Vastar $500,000 as consideration for terminating
     the lease and entering into a new lease agreement and $150,000 as
     consideration for terminating the Management Agreement.

6.   At closing, ARCO shall pay to Vastar the PV, calculated a 6.25% (Vastar's
     cost of debt) the difference between Vastar's current annual net rent of
     $1,748,862.50 ($6.25/sq. ft. on 279,818 square feet) and the net rent
     payable under the new lease from the commencement date through December 31,
     2003, prorated for partial months. That amount will be reduced by the PV of
     the amounts Vastar owed ARCO under the audit settlement, security system,
     and fire, life, safety system.

7.   Vastar shall pay ARCO $230,000 for a reduction in purchase value due to
     Lexington purchasing insurance on the behalf of Vastar, as tenant.

8.   The new lease will cover the entire building equating to 327,325 net
     rentable square feet. ARCO will also pay Vastar for the difference between
     $6.25 per square feet and the net rent payable under the New Lease on
     47,507 square feet with is Cabot's Leased Premises from the commencement
     date of the new lease through December, 31, 2003, prorated for partial
     months. At closing, ARCO shall pay Vastar $475,000 for improvement
     allowance for the Cabot space.

9.   During the fourth quarter of 2003, ARCO and Vastar will attempt in good
     faith to agree on the then current fair market rent on a gross rent basis
     for the building. If 95% of market rent is below the rent specified in the
     new lease for the remainder of the initial ten year term, ARCO shall pay
     Vastar the PV of the difference calculated at Vastar's then cost of debt.
     If 95% of the market rent is above, Vastar shall pay ARCO as in the same
     manner. There is an arbitration mechanism in place should ARCO and Vastar
     not agree on the fair market rent for the building.
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10.  At closing, ARCO shall pay Vastar $250,000 to use such funds to expand the
     parking lot located at the southern end of the premises.

11.  ARCO indemnifies Vastar, its agents and employees harmless from any and all
     liabilities of any kind or nature, including reasonable attorneys' fees in
     connection with Environmental Activities, any Hazardous Materials Claims,
     or any violation of ARCO of a Hazardous Materials Law with respect to the
     building which arose or occur prior to Closing and were not caused by
     Vastar and Environmental Activities in violation of any Hazardous Material
     Laws during the Initial Term which occur offsite and migrate to the
     building which is caused by a party other than Vastar or the landlord.

                                   LEASE

Landlord:                      Lexington Memorial L. L. C.
                               a Delaware limited liability company
                               355 Lexington Avenue
                               New York, New York 10017

Tenant:                        Vastar Resources, Inc.

Commencement Date:             September 16, 1999

Termination Date:              September 14, 2009 (10 year term - Initial Term)

Premises:                      Office building and land and all improvements
                               located at 15375 Memorial Drive, Houston, TX
                               77079

Renewal Terms:                 4 separate renewal terms of 5 years each - notice
                               not less than 12 months prior to end of the then
                               current Term

Initial Term Rent:             Lease years 1-3 - $3,273,250 annually - $272,771
                               monthly
                               Lease years 4-7 - $3,436,913 annually - $286,409
                               monthly
                               Lease years 8-10 - $3,600,575 annually - $300,048
                               monthly

Renewal Term Rent:             100% of Market Rent - fair market rent value

Net Lease:                     The Rent is free of taxes, assessments, utility
                               charges, operating expenses, refurbishings,
                               insurance premiums. Landlord is responsible for
                               capital expenditures for both Structural Elements
                               and Mechanical Elements

Tenant's Obligations:          Tenant agrees to pay any and all taxes (including
                               but not limited to real property and personal
                               property taxes, franchise taxes, business and
                               occupational license taxes, ad valorem sales,
                               use, single business, gross receipts, transaction
                               privileges, rent or other excise taxes) and other
                               assessments levied or assessed against the
                               Premises.
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Alterations by Tenant:   Tenant shall have the right of altering, improving,
                         replacing, repairing or modifying the facilities;
                         provided however, that any alterations, improvements,
                         replacements, repairs or modifications to Structural
                         Elements or to the Premises' mechanical,
                         electrical/power, fire protection/life safety,
                         plumbing, sprinkler and HVAC systems and any other
                         alterations, improvements, replacements, repairs or
                         modifications in excess of $200,000 shall require the
                         prior written approval of the Landlord.  Tenant shall
                         have the duty to provide Landlord with "as built" blue
                         prints and specifications for all alternation and
                         improvements to the Premises made by Tenant.  Tenant
                         has the right to expand the parking lot at the southern
                         end of the Premises and to construct a building of up
                         to approximately 27,000 square feet to be used by
                         Tenant primarily for storage including file room and
                         file storage.

Capital Improvements
Funded by Landlord:      Structural Elements shall mean the foundation,
                         floor/ceiling slabs, roof, exterior walls, glass and
                         mullions, columns and beams.  Mechanical Elements shall
                         mean the HVAC system, electrical system, mechanical
                         system, plumbing and sprinkler system, fire
                         protection/life safety systems and elevator system.
                         The roof shall be considered a Structural Element
                         during the Initial Term and a Mechanical Element during
                         any Renewal Term.  (Tenant would have to pay the
                         amortized portion of the actual cost plus interest of
                         the improvement over its useful life during the Term of
                         the Lease.)

Landlord Insurance:      Landlord is responsible for carrying insurance for the
                         benefit of Landlord, Tenant, and mortgagee which
                         includes broad form commercial general liability on a
                         pre-occurrence basis with an aggregate limit of not
                         less than $10MM and a pre-occurrence limit of not less
                         than $5MM or such greater limits as may be reasonably
                         required from time to time; property insurance;
                         business interruption insurance; boiler insurance;
                         sprinkler leakage insurance; such other insurance as is
                         customarily obtained by owner of similar properties.

Tenant's Insurance:      Tenant shall provide workers' compensation insurance
                         (including employers' liability insurance) covering all
                         persons employed at the Premises by Tenant.  Tenant
                         shall obtain from all contractors builder's risk
                         completed coverage for 100% of contract price on a non-
                         reporting form, deleting all co-insurance provisions
                         against all types of risks with the addition of damage
                         due to faulty materials, workmanship and errors in
                         design and including permission to occupy the Premises
                         and owner's contingent or protective liability
                         insurance covering claims not covered by or under the
                         terms of the above-mentioned comprehensive general
                         liability insurance policy.
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Assignment and Subletting:        Tenant, may without Landlord's consent, but
                                  upon 30 days prior written notice by Tenant to
                                  Landlord, assign this Lease or sublet the
                                  Premises or any portion thereof.

Holding Over:                     Tenant shall have the right, without
                                  Landlord's consent, after written notice
                                  delivered to Landlord at least 60 days prior
                                  to the end of the Initial Term to retain
                                  possession of the Premises or any part thereof
                                  after the termination of the Term for a period
                                  not to exceed 3 months on the same terms and
                                  conditions under the Lease including the Rent
                                  then in effect. If at the end of the 3 month
                                  period, Tenant remains in possession of the
                                  Premises without Landlord's express written
                                  consent, Tenant shall pay Landlord 150% of the
                                  3 month grace period as set forth in the
                                  Section and Landlord shall have all other
                                  remedies against Tenant available to Landlord
                                  at law and in equity, including but not
                                  limited to consequential damages.

Roof Top Rights:                  Tenant may install satellite dishes, antennas,
                                  receivers, transmitters or other
                                  telecommunication and all related cabling and
                                  wiring without Landlord's consent.

Parking:                          Tenant is hereby granted unlimited parking
                                  rights and privileges in the parking structure
                                  and lots on the Premises at no charge.

Notices and Demands:              All in writing and shall be deemed properly
                                  given by facsimile with confirmation or upon
                                  actual receipt by nationally recognized
                                  overnight delivery service provided for
                                  receipted delivery or within 2 business days
                                  being placed in the U.S. certified or
                                  registered mail, return receipt requested,
                                  postage paid

Consent, Permission or Approval:  Shall be in writing and shall not be
                                  unreasonably withheld or delayed. If refused,
                                  must give the basis and adequate reasons for
                                  such refusal.

Arbitration:                      All disputes related to this Agreement will
                                  subject to the arbitration provision under
                                  Exhibit "B".

                                  Exhibit "A"
                          Description of the Premises

                                  Exhibit "B"
                              Arbitration Program

                                  Exhibit "C"
                               Prevailing Market

                                  Exhibit "D"
                              Permitted Exceptions

                                  Exhibit "E"
                                Expansion Areas