Exhibit 10.6

PROMISSORY NOTE

Date: June 1, 2006

Maker: LAZARUS ENERGY LLC

Maker’s Mailing Address (including county):

4400 Post Oak Parkway, 24th Floor

Houston, Texas 77027

Payee: NOTRE DAME INVESTORS, INC.

Place for Payment (including county):

5404 Holly

Bellaire, Harris County, Texas 77401

Principal Amount: $8,000,000.00

Annual Interest Rate on Unpaid Principal Balance: 6.0%

Final Maturity: June 1, 2010

Terms of Payment (principal and interest):

 

  (i) Interest shall begin to accrue immediately on a 365/366 day basis, as the
case may be. Principal payments of $1,000,000.00 along with any unpaid, accrued
interest shall be due on or before June 1 and December 1 of each year until
Final Maturity, with the first such payment due on December 1, 2006 (or, if the
due date of such payment is not a Business Day, the next succeeding Business
Day). For purposes of this note (this “Note”), “Business Day” means any day
except Saturday, Sunday or any day on which banks are generally not open for
business in the City of Houston, Texas.

 

  (ii) Pre-payments, either in whole or in part, may be allowed at any time
without penalty or discount.

Security for Payment: First Lien Deed of Trust, of even date herewith, executed
by Maker to Steven R. Brook, Trustee, for the benefit of Payee, on certain real
and personal property in Wilson County, Texas (“Deed of Trust”).

Maker promises to pay to the order of Payee at the place for payment stated
above and according to the terms of this Note the principal amount plus interest
at the rate stated above. All unpaid amounts shall be due and payable on the
date of final maturity.

If Maker defaults in the payment of this Note or in the performance of any
obligation in the Deed of Trust, and the default continues after Payee gives
Maker notice of the default with 10 calendar days to cure such default, the
Payee may declare the unpaid principal balance and accrued and unpaid interest
on this Note immediately due and payable. Any event of default by Maker as
declared by any other lender providing credit on, for or with the Security
described herein will be considered to be a default under this agreement and, in
such event, the Payee may declare the unpaid principal balance and any accrued
and unpaid interest on this Note immediately due and payable. Any acceleration
of maturity or demand for payment by any other lender providing credit to Maker
will be considered to be a default under this agreement and the Payee may
declare the unpaid principal balance and any earned unpaid interest on the

Note to be immediately due and payable. Maker waives all demands for payment,
presentations for payment, notices of intention to accelerate maturity, notices
of acceleration of maturity, protests, and notices of protest, to the extent
permitted by law.

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If this Note or any instrument securing or collateral to it is given to an
attorney for collection or enforcement, or if suit is brought for collection or
enforcement, or if it is collected or enforced through probate, bankruptcy, or
other judicial proceeding, then Maker shall pay Payee all costs of collection
and enforcement, including reasonable attorney’s fees and court costs, in
addition to other amounts due.

Interest on the debt evidenced by this Note shall not exceed the maximum amount
of nonusurious interest that may be contracted for, taken, reserved, charged, or
received under law; any interest in excess of that maximum amount shall be
credited on the principal of the debt or, if that has been paid, refunded. On
any acceleration or required or permitted prepayment, any such excess shall be
canceled automatically as of the acceleration or prepayment or, if already paid
credited on the principal of the debt or, if the principal of the debt has been
paid, refunded. This provision overrides other provisions in this and all other
instruments concerning the debt.

When the context requires, singular nouns and pronouns include the plural.

[Signature Page Follows]

 

2

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IN WITNESS WHEREOF, Maker has executed and delivered this Note as of the date
first above written.

 

LAZARUS ENERGY LLC By:   Lazarus Energy Holdings LLC, its sole member By:   LOGO
[g348276g69h43.jpg]   Jonathan Carroll   Director

Pay to the Order of STEVEN R. BROOK, ESCROW AGENT.

 

NOTREDAM E INVESTORS, INC. By:   LOGO [g348276g73s00.jpg]   Roland Oberlin,
President

Pay to the Order of Roland Oberlin as successor Escrow Agent, but without
warranty by or recourse on the undersigned:

 

  LOGO [g348276g88j90.jpg]   Steven R. Brook, Escrow Agent

This Note is further governed by the terms of that certain Intercreditor and
Subordination Agreement, a copy of which is attached hereto and incorporated by
reference herein.