Exhibit 10.6

CONFIDENTIAL
AMENDMENT NO. 2
TO
          MASTER LICENSE AGREEMENT          
(formerly the Volume License Agreement)
     THIS AMENDMENT NO. 2 TO MASTER LICENSE AGREEMENT (“Amendment No. 2”) is
made and entered into as of this 1st day of June, 2002 by and between Syntroleum
Corporation, a Delaware corporation (“Licensor”), and Ivanhoe Energy Inc., a
company organized under the laws of the Yukon, Canada (“Licensee”).
Recitals
     A.     WHEREAS, Licensor and Licensee previously entered into that certain
Volume License Agreement dated as of April 26, 2000, as amended by Amendment
No. 1 to Volume License Agreement dated as of October 11, 2000 which, among
other things, changed the Volume License Agreement to a Master License
Agreement. (collectively, the “Master License Agreement”); and
     B.     WHEREAS, Licensor and Licensee desire to amend certain provisions of
the Master License Agreement as set forth in this Amendment No. 2.
     NOW, THEREFORE, in consideration of the mutual covenants and agreements set
forth in this Amendment No. 2, the Parties agree as follows. Unless otherwise
provided in this Amendment No. 2, capitalized terms used in this Amendment No. 2
but not defined shall have the meanings set forth in the Master License
Agreement.
     1.     Attachment 3 to the Master License Agreement is amended and restated
to read in its entirety as set forth on Exhibit A to this Amendment No. 2.
     2.     Except as expressly amended by this Amendment No. 2, the Master
License Agreement is and shall remain in full force and effect in

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accordance with its terms and the parties hereby ratify and reaffirm the Master
License Agreement as amended hereby.

            Licensor
SYNTROLEUM CORPORATION

      By:   /s/ Larry J. Weick         Larry J. Weick, Vice President           
    Licensee
IVANHOE ENERGY INC.

      By:   /s/ E. Leon Daniel         E. Leon Daniel, President & CEO         
 

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Exhibit A to Amendment Number 2
 
ATTACHMENT 3
 
to Master License Agreement
 
License Fee Calculation

I.   For purposes of this Attachment 3, the following terms shall have the
meanings ascribed thereto:   A.   “Licensed Plant” means the Licensed Plant in
which a Site License Agreement for such plant is issued to and remains in the
name of the Licensee who has executed this Agreement with Licensor and, in which
the Participating Interest held by Licensee, or collectively by Licensee and any
other Person who has executed a license agreement (which is applicable to the
Licensed Plant) with Licensor, represents at least 10% of the entire
Participating Interest not held by a governmental authority regardless of
operatorship of the Licensed Plant.   B.   “Large Licensed Plant” means a
Licensed Plant under a single Site License Agreement with a maximum daily design
capacity, as defined in a single Process Design Package, of nominally 180,000 or
more barrels of Synthetic Product per day and which may be constructed in two
phases of nominally 90,000 or more barrels per day for each phase and with the
second phase constructed either concurrently with the first phase or in a
separate consecutive period starting no more than 1 year following the start of
construction of the first phase.   C.   “Royalty Rate” shall mean (i) the lowest
royalty rate per Barrel of Synthetic Product accepted by Licensor for a Site
License Agreement with a non-Affiliate for a facility of comparable size, in the
Licensed Territory, which is not under a master preferred license agreement,
during the twelve (12) months immediately preceding the execution date of the
applicable Site License Agreement under this Agreement, or (ii) if no such Site
License Agreement has been executed during the twelve (12) months immediately
preceding, then the royalty rate per Barrel of Synthetic Product in the last
Site License Agreement with a non-Affiliate, in the Licensed Territory, executed
by Licensor, which is not under a master preferred license agreement, or
(iii) if none of the foregoing applies, then US$0.50 per Barrel of Synthetic
Product. Market Royalty Rate does not include the catalyst price as provided for
under Section 2.03 of this Agreement.   D.   “BLS Index” shall mean the index
for January of the year in question represented by the Producer Price Index for
Industrial Commodities as published by the Bureau of Labor Statistics, U.S
Department of Labor, using the year 1982 as the base index equal to 100. If, at
any time, the above index should cease to be published, then

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    another suitable index published by the U.S. Government or other
authoritative organization and generally recognized by the trade as
authoritative with respect to changes in the U.S. of equivalent commodity costs
shall be used.   II.   For each Site License Agreement executed under this
Agreement for a Licensed Plant with a maximum daily design capacity, as defined
by the Process Design Package, of less than 30,000 barrels of Synthetic Product
per day, Licensee agrees to pay License Fees to Licensor on a prepaid license
basis as follows:

  A.   Licensee agrees to pay Licensor a one-time, prepaid License Fee
calculated in accordance with the following formula:         License Fee = “C” x
350 x 7.5 x “R” wherein:

          “C”   =  
the maximum daily design capacity, as defined by the Process Design Package, of
such Licensed Plant to produce Marketable Products measured in Barrels of
Synthetic Product per day for which such Licensed Plant is originally designed
and constructed, and
“R”   =  
the Royalty Rate.

      and payable in installments as follows:

  (i)   20% within thirty (30) days after the execution of the Site License
Agreement for such Licensed Plant;     (ii)   30% within thirty (30) days after
delivery of the Process Design Package or within one hundred twenty (120) days
after the execution of the Site License Agreement for such Licensed Plant,
whichever first occurs;     (iii)   20% within thirty (30) days after the
commencement of field construction move-in:     (iv)   30% within one-hundred
and twenty (120) days after the Start-Up Date of the Licensed Plant or a
successful Performance Test as specified in the Process Guarantee and
Performance Test Agreement, whichever first occurs.

  B.   Notwithstanding any other provision of this Agreement, payments made by
Licensee to Licensor under Section 5.01 of this Agreement and Section 5 of
Amendment No. 1 to Volume License Agreement between Licensee and Licensor dated
October 11, 2000, shall be fully credited against the License Fees payable by
Licensee to Licensor under Section II.A.

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  C.   In the event the actual production capacity of any Licensed Plant, under
II.A. above, is determined to have either exceeded the original maximum daily
design capacity established in its Site License Agreement or is increased
through major equipment modification, by more than five percent (5%) or by more
than 500 barrels per day, at any time after the Start-up Date, Licensee shall
pay Licensor an additional License Fee, on a prepaid basis, equal to the
difference between (a) the prepaid License Fee as would have been calculated
with the higher production capacity for such Licensed Plant substituted for “C”
in the calculation method set forth in II.A. above, and (b) the License Fee as
would have been calculated for such Licensed Plant by the method set forth in
II.A. above using the original maximum daily design capacity established in each
Site License Agreement. The incremental License Fee due will be reduced by any
previous incremental adjustments. Such additional License Fee shall be payable
within thirty (30) days after the end of the calendar year in which such
increase in production capacity of such Licensed Plant occurs. Incremental
License Fees for increased production capacity in any Licensed Plant shall not
be due if the increased production capacity is the result of the initial use of
Licensee Patent Rights or Licensee Technical information. The total cumulative
incremental capacity adjustments under each Site License Agreement will be
limited to 50 percent of the initial maximum daily capacity under such
Agreement.     D.   Upon payment of all fees due under the Site License
Agreement for each Licensed Plant under this Section II, Licensee shall be
deemed to have acquired a fully paid license for such Licensed Plant up to the
original maximum daily design capacity or any adjusted daily design capacity
made under the provisions of Section II.B. above. Any additional incremental
increases in the Licensed Plant capacity will be subject to additional License
Fees as calculated under incremental adjustments pursuant to this Section II.

III.   For each Site License Agreement executed under this Agreement for a
Licensed Plant with a maximum daily design capacity, as defined in the Process
Design Package, equal to or more than 30,000 barrels but less than nominally
180,000 barrels of Synthetic Product per day, Licensee agrees to pay License
Fees to Licensor as follows:

  A.   Prepaid License Fee.

1. Licensee agrees to pay Licensor a one-time, prepaid License Fee calculated in
accordance with the following formula:
License Fee = “C” x 350 x 7.5 x “R” x .50 wherein:

          “C”   =  
the maximum daily design capacity, as defined by the Process Design Package, of
such Licensed Plant to produce Marketable Products measured in Barrels of
Synthetic Product per day for

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which such Licensed Plant is originally designed and constructed, and
       
 
“R”   =  
the Royalty Rate.

      and payable in installments as follows:

  (i)   20% within thirty (30) days after the execution of the Site License
Agreement for such Licensed Plant;     (ii)   30% within thirty (30) days after
delivery of the Process Design Package or within one hundred twenty (120) days
after the execution of the Site License Agreement for such Licensed Plant,
whichever first occurs;     (iii)   20% within thirty (30) days after the
commencement of field construction move-in;     (iv)   30% within one-hundred
and twenty (120) days after the Start-Up Date of the Licensed Plant or a
successful Performance Test as specified in the Process Guarantee and
Performance Test Agreement, whichever first occurs.

2. Notwithstanding any other provision of this Agreement, payments made by
Licensee to Licensor under Section 5.01 of this Agreement and Section 5 of
Amendment No. 1 to Volume License Agreement between Licensee and Licensor dated
October 11, 2000, shall be credited against the License Fee payments due by
Licensee to Licensor under Section III.A.1. at the rate of up to 50%, such that
the Licensor shall receive a cash payment of at least 50% of the scheduled
installment payment under Section III.A.1.
3. In the event the actual production capacity of any Licensed Plant for which a
prepaid License Fee has been paid under Section III.A. above is determined to
have exceeded the original maximum daily design capacity established in its Site
License Agreement by more than five percent (5%) or by more than 500 barrels per
day, at any time after the Start-up Date, Licensee shall pay Licensor an
additional License Fee, on a prepaid basis, equal to the difference between
(a) the prepaid License Fee as would have been calculated with the higher
production capacity for such Licensed Plant substituted for “C” in the
calculation method set forth in II.A. above, and (b) the License Fee as would
have been calculated for such Licensed Plant by the method set forth in
Section III.A. above using the original maximum daily design capacity
established in each Site License Agreement. Such additional License Fee shall be
payable within thirty (30) days after the end of the calendar year in which such
increase in production capacity of such Licensed Plant occurs. Incremental
License Fees for increased production capacity in any Licensed

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Plant shall not be due if the increased production capacity is the result of the
initial use of Licensee Patent Rights or Licensee Technical information. The
total cumulative incremental capacity adjustments under each Site License
Agreement will be limited to 50 percent of the initial maximum daily capacity
under such Agreement.

  B.   Running Royalty License Fees.

  1.   In addition to the prepaid License Fee payable by Licensee to Licensor in
accordance with Paragraph A above, Licensee agrees to pay Licensor, on or before
thirty (30) days after the end of each calendar month, a monthly running royalty
license fee based on the actual operation of the Licensed Plant and calculated
in accordance with the following formula:         Monthly Running Royalty
License Fee = “MP” x (“R” x .50) x “BLS”         wherein:

          “MP”   =  
the total monthly production in Barrels of Synthetic Product during a calendar
quarter as measured in a manner specified in the Process Design Package,
“R”   =  
the Royalty Rate, and
“BLS”   =  
the factor equal to (a) the BLS Index for the calendar year in which the payment
is being made divided by (b) the BLS Index applicable as of the Effective Date
of the Master License Agreement.

IV.   For each Site License Agreement executed under this Agreement for a Large
Licensed Plant, Licensee agrees to pay License Fees to Licensor as follows:

  1.   First Phase

  A.   Prepaid License Fee         25% of the Prepaid License Fee for the first
nominal 90,000 barrels per day of a Large Licensed Plant (“First Phase”) will be
paid in accordance with the installment payment schedule set forth in
Section III.A. above         AND     B.   Running Royalty License Fees        
The remaining License Fee in respect to the First Phase of a Large Licensed
Plant, will be paid, on or before thirty (30) days after the end of each
calendar month, as a running royalty license fee (“First Phase

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      Running Royalty License Fee”) per barrel of actual production of
Marketable Products for the life of the project. The First Phase Running Royalty
License Fee rate, will be equal to 75% of the standard Royalty Rate for a
Licensed Plant current at the time of execution of the Site License Agreement
and escalated annually thereafter based upon the Bureau of Labor Statistics
published inflation index, calculated as follows:         First Phase Running
Royalty License Fee = “MP x (“R” x 0.75) x “BLS”         Wherein:

          “QP”   =  
total monthly production in Barrels of Marketable Products during a calendar
month
       
 
“R”   =  
the Royalty Rate
       
 
“BLS”   =  
the factor equal to (a) the BLS index for the calendar year in which the payment
is being made divided by (b) the BLS Index applicable as of the Effective Date
of the Master License Agreement.

  2.   Second Phase         For the second nominal 90,000 barrels per day
minimum or more for the Large Licensed Plant under the same Site License
Agreement referenced above (“Second Phase”) that will be included in a combined
design with the First Phase as a single project for purposes of preparation of
the Process Design Package, with the Second Phase constructed either
concurrently with the First Phase or in a separate consecutive period starting
no more than 1 year following the start of construction of the First Phase, the
License Fee associated with the Second Phase of the Large Licensed Plant shall
be paid as follows:

  A.   Prepaid License Fees

25% of the Prepaid License Fee for the Second Phase will be payable in
installments as follows:
(i) 50% at the closing of the financing on the First Phase with respect to a
Large Licensed Plant covered by a Site License (Financial Closing)
(ii) 20% within thirty (30) days after the commencement of field construction
move-in; and
(iii) 30% at the satisfactory Performance Test of the Second Phase of the Large
Licensed Plant.

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AND

  B.   Running Royalty License Fees         The remaining License Fee in respect
to the Second Phase of the Large Licensed Plant, will be paid, on or before
thirty (30) days after the end of each calendar month, as a running royalty
license fee (“Second Phase Running Royalty License Fee”) per barrel of actual
production of Marketable Products for the life of the project. The Second Phase
Running Royalty License Fee rate, will be equal to 50% of the standard Royalty
Rate for the Licensed Plant current at the time of execution of the Site License
Agreement and escalated annually thereafter based upon the Bureau of Labor
Statistics published inflation index, calculated as follows:         Second
Phase Running Royalty License Fee = “MP x (“R” x 0.50) x “BLS”         Wherein:

          “MP”   =  
total monthly production in Barrels of Marketable Products during a calendar
month
       
 
“R”   =  
the Royalty Rate
       
 
“BLS”   =  
the factor equal to (a) the BLS index for the calendar year in which the payment
is being made divided by (b) the BLS Index applicable as of the Effective Date
of the Master License Agreement.

  3.   Accumulated credits, if any, to which Licensee is entitled against the
License Fee under the Site License may be applied at Financial Closing and any
remaining credits may be applied the thirty (30) days after commencement of
field construction move-in.

V.   All payments required hereunder shall include a statement showing the
details supporting the calculation of the License Fees being paid. Licensee
shall keep accurate and complete records of all natural gas feedstock processed
(volume and composition) and all Synthetic Product produced at and either used
internally within or removed from each Licensed Plant to enable verification of
statements and payments rendered to Licensor hereunder. Licensee agrees to
permit Licensor, at Licensor’s expense, to inspect such records on reasonable
notice and at reasonable

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    intervals during normal business hours to verify the license fees paid and
payable under this Agreement.   VI.   If the Licensee can not achieve financing
on commercially reasonable terms for the Licensed Plant or if the project is
terminated for any reason prior to such time, Licensee shall retain 25% of the
License Fee payments made to Licensor for the project up to that date and the
remaining 75% shall be credited to any future Licensed Plant that is initiated
within 15 years from the Effective Dates of the Master License Agreement.

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