FIRST SUPPLEMENTAL INDENTURE to INDENTURE Dated as of December 1, 2005

Exhibit 4.1

FIRST SUPPLEMENTAL INDENTURE

to

INDENTURE

Dated as of December 1, 2005

among

CHAPARRAL ENERGY, INC.

as Issuer,

The GUARANTORS named therein

and

WELLS FARGO BANK, NATIONAL ASSOCIATION

as Trustee

8 ¹/2% Senior Notes due 2015

FIRST SUPPLEMENTAL INDENTURE

This FIRST SUPPLEMENTAL INDENTURE (this “Supplemental Indenture”), dated as of August 24, 2006, is among Chaparral Energy, Inc. (or its successor), a Delaware corporation (the “Issuer”), the Guarantors (the “Guarantors”) under the Indenture referred to below, and Wells Fargo Bank, National Association, as trustee under the Indenture referred to below (the “Trustee”).

W I T N E S S E T H :

WHEREAS the Issuer has heretofore executed and delivered to the Trustee an Indenture (as such may be amended from time to time, the “Indenture”), dated as of December 1, 2005, providing for the issuance of its 8 ¹/2% Senior Notes due 2015 (the “Notes”);

WHEREAS the Issuer and the Guarantors deem it to be in their best interest to enter into this Supplemental Indenture for the purpose of amending certain provisions of the Indenture relating to the denominations in which the Notes may be issued; and

WHEREAS pursuant to Section 9.1 of the Indenture, the Trustee, the Issuer and the Guarantors are authorized to execute and deliver this Supplemental Indenture;

NOW THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the receipt of which is hereby acknowledged, the Issuer, the Guarantors and the Trustee mutually covenant and agree for the equal and ratable benefit of the Holders as follows:

1. Definitions. (a) Capitalized terms used herein without definition shall have the meanings assigned to them in the Indenture.

(b) For all purposes of this Supplemental Indenture, except as otherwise herein expressly provided or unless the context otherwise requires: (i) the terms and expressions used herein shall have the same meanings as corresponding terms and expressions used in the Indenture; and (ii) the words “herein,” “hereof” and “hereby” and other words of similar import used in this Supplemental Indenture refer to this Supplemental Indenture as a whole and not to any particular section hereof.

2. Denominations of Senior Notes. The provisions of each of the following sections of the Indenture are hereby amended as follows:

3. Ratification of Indenture; Supplemental Indentures Part of Indenture. Except as expressly amended hereby, the Indenture is in all respects ratified and confirmed and all the terms, conditions and provisions thereof shall remain in full force and effect. This Supplemental Indenture shall form a part of the Indenture for all purposes, and every Holder heretofore or hereafter authenticated and delivered shall be bound hereby.

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4. Governing Law. THIS SUPPLEMENTAL INDENTURE SHALL BE GOVERNED BY AND CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

5. Trustee Makes No Representation. The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or for or in respect of the recitals contained herein, all of which are made solely by the Issuer.

6. Multiple Counterparts. The parties may sign multiple counterparts of this Supplemental Indenture. Each signed counterpart shall be deemed an original, but all of them together represent one and the same agreement.

7. Headings. The headings of this Supplemental Indenture have been inserted for convenience of reference only, are not to be considered a part hereof, and shall in no way modify or restrict any of the terms or provisions hereof.

[Signatures on following pages]

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IN WITNESS WHEREOF, the parties hereto have caused this Supplemental Indenture to be duly executed as of the date first above written.

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