EXHIBIT 4.1


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                             PARKER DRILLING COMPANY
                            and Subsidiary Guarantors

                          9 3/4% SENIOR NOTES DUE 2006

                                 ---------------

                          THIRD SUPPLEMENTAL INDENTURE

                           Dated as of April 30, 2002

             Supplementing the Indenture dated as of March 11, 1998

                                 ---------------

                              JPMORGAN CHASE BANK,
                                   as Trustee



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                          THIRD SUPPLEMENTAL INDENTURE


         This Third Supplemental Indenture dated and effective as of April 30,
2002 (the "Third Supplemental Indenture") is made and entered into by and among
Parker Drilling Company, a Delaware corporation (the "Company"), each of the
parties identified under the caption "Existing Subsidiary Guarantors" on the
signature pages hereof (the "Existing Subsidiary Guarantors"), each of the
parties identified under the caption "New Subsidiary Guarantors" on the
signature pages hereof (the "New Guarantors") and JPMorgan Chase Bank, a New
York banking organization, as Trustee (the "Trustee"), formerly known as The
Chase Manhattan Bank and successor by merger to Chase Bank of Texas, National
Association.

                RECITALS OF THE COMPANY AND SUBSIDIARY GUARANTORS

         WHEREAS, the Company, the Existing Subsidiary Guarantors and the
Trustee have executed and delivered an Indenture dated as of March 11, 1998 by
and among the Company, the Trustee and the Subsidiary Guarantors (as
supplemented by the First and Second Supplemental Indentures, the "1998
Indenture") for the benefit of one another and for the ratable benefit of the
Holders of the 9 3/4% Senior Notes due 2006, Series D (the "Notes") and pursuant
to which the Existing Subsidiary Guarantors have agreed, jointly and severally,
to unconditionally guarantee the due and punctual payment of the principal of,
premium, if any, and interest on the Notes and all other amounts due and payable
under the 1998 Indenture and the Notes by the Company ; and

         WHEREAS, Section 9.01(a)(vi) and (vi) of the 1998 Indenture provides
that under certain conditions the Company and the Trustee may, without the
consent of any Holder of a Note, amend or supplement the 1998 Indenture to add
any Restricted Subsidiary as an additional Subsidiary Guarantor as provided in
Section 10.02 of the 1998 Indenture or to evidence the succession of another
Person to any Existing Subsidiary Guarantor pursuant to Section 10.04 of the
1998 Indenture and the assumption by any such additional Subsidiary Guarantor of
the covenants and agreements of such Subsidiary Guarantor contained in the 1998
Indenture and in the Subsidiary Guarantee of such Subsidiary Guarantor and to
release a Subsidiary Guarantor pursuant to Section 10.05;

         WHEREAS, the Company has determined that the New Guarantors are
required to be added as Subsidiary Guarantors pursuant to Section 10.02 of the
1998 Indenture as a result of said New Guarantors having guaranteed the
Indebtedness of the Company under the Senior Credit Facility;

         WHEREAS, Section 10.02 of the 1998 Indenture provides that as a result
of said actions the following is required: (i) the execution and delivery by the
New Guarantors of this Third Supplemental Indenture whereby the New Guarantors
agree to be bound by the terms of the 1998 Indenture as applicable to a
Subsidiary Guarantor; and (ii) the execution of a Subsidiary Guarantee of the
Notes by the New Guarantors; and

         WHEREAS, the Company has determined that certain Subsidiary Guarantors
should be released from their obligations under the Indenture and its respective
Subsidiary Guarantee as a result of being merged into an Existing Subsidiary
Guarantor; and

         WHEREAS, the execution and delivery of this Third Supplemental
Indenture has been duly authorized by a Board Resolution of the respective
Boards of the Company, the Existing Subsidiary Guarantors and each of the New
Guarantors; and

         WHEREAS, all conditions and requirements necessary to make this Third
Supplemental Indenture valid and binding upon the Company, the Existing
Subsidiary Guarantors and the New


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Guarantors, and enforceable against the Company, the Existing Subsidiary
Guarantors and the New Guarantors in accordance with its terms, have been
performed and fulfilled.

         NOW, THEREFORE, in consideration of the above premises, the parties
hereto mutually covenant and agree for the equal and ratable benefit of the
respective Holders of the Notes, as follows:

                                    ARTICLE I

                                 NEW GUARANTORS

         Section 1.1. New Guarantors. The New Guarantors, by execution and
delivery of this Third Supplemental Indenture, hereby agree to be bound by the
terms of the Indenture as a Subsidiary Guarantor.

         Section 1.2. Guarantee of Each New Guarantor. Attached as Exhibit A and
incorporated herein by reference is the Subsidiary Guarantee of each New
Guarantor in the form prescribed in the 1998 Indenture, by which each New
Guarantor agrees to guarantee the obligations of the Company, in accordance with
the terms set out in the Subsidiary Guarantee.

                                   ARTICLE II

                              RELEASE OF GUARANTORS

         Section 2.1 Merger of Guarantors. On or about July 31, 1998, Hercules
Rig Corp. merged into Hercules Offshore Corporation and Parker Drilling Offshore
Company merged into Hercules Offshore Corporation in accordance with Section
10.04.

         Section 2.2 Release of Guarantors. Because Hercules Offshore
Corporation, now Parker Drilling Offshore Corporation, is an Existing Guarantor,
and has executed a supplemental indenture to the Indenture and a Subsidiary
Guarantee, Hercules Rig Corp. and Parker Drilling Offshore Company are hereby
released from any further obligations under the Indenture and their respective
Subsidiary Guarantees in accordance with Section 10.05.

                                   ARTICLE III

                    PARTICULAR REPRESENTATIONS AND COVENANTS

         Section 3.1. Authority. The Company and each Existing Subsidiary
Guarantor is duly authorized by a resolution of its respective Board of
Directors to execute and deliver this Third Supplemental Indenture, and all
corporate action on its part required for the execution and delivery of this
Third Supplemental Indenture has been duly and effectively taken.

         Section 3.2. Correctness of Recitals. The Company and each Existing
Subsidiary Guarantor represent and warrant that all recitals and statements in
this Third Supplemental Indenture are true and correct.

                                   ARTICLE IV

                             CONCERNING THE TRUSTEE

         Section 4.1 Acceptance of Trusts. The Trustee accepts the trusts
hereunder and agrees to perform same, but only upon the terms and conditions set
forth in the Indenture.


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         Section 4.2 Responsibility for Recitals. The recitals and statements
contained in this Third Supplemental Indenture shall be taken as recitals and
statements of the Company, the Existing Subsidiary Guarantors and the Trustee
assumes no responsibility for the correctness of same. The Trustee makes no
representations as to the validity or sufficiency of this Third Supplemental
Indenture, except that the Trustee is duly authorized to deliver it.


                                    ARTICLE V

                            MISCELLANEOUS PROVISIONS

         Section 5.1 Relation to the 1998 Indenture. This Third Supplemental
Indenture shall become effective immediately upon execution and delivery. All
terms and conditions in it shall form a part of the 1998 Indenture as fully and
with the same effect as if all such terms and conditions had been set forth in
the 1998 Indenture. The 1998 Indenture is hereby ratified and confirmed and
shall remain and continue in full force and effect in accordance with its terms,
as supplemented by this Third Supplemental Indenture. The 1998 Indenture and the
Third Supplemental Indenture shall be read, taken and construed together as one
instrument. Capitalized terms used but not defined in this Third Supplemental
Indenture have the meaning ascribed to such terms in the 1998 Indenture.

         Section 5.2 Execution in Counterparts. This Third Supplemental
Indenture may be executed in several counterparts, each of which shall be deemed
an original, but all of which together shall constitute one instrument.

         Section 5.3 Governing Law. The internal laws of the State of New York
shall govern and be used to construe this Third Supplemental Indenture and the
new notations of Subsidiary Guarantees executed and delivered pursuant to it.

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

                                        PARKER DRILLING COMPANY


                                        By:     /s/ James J. Davis
                                           ------------------------------------
                                        Name:   James J. Davis
                                        Title:  Sr. Vice President-Finance and
                                                Chief Financial Officer


                                        JPMORGAN CHASE BANK, as Trustee


                                        By:    /s/ Mauri J. Cowen
                                           ------------------------------------
                                        Name:  Mauri J. Cowen
                                        Title: Vice President and Trust Officer


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                            EXISTING SUBSIDIARY GUARANTORS:

                            Parker Drilling Company of Oklahoma, Incorporated
                            Parker Drilling Company Limited (Nevada)
                            Parker Drilling Company Limited (Oklahoma)
                            Choctaw International Rig Corp.
                            Parker Drilling Company of New Guinea, Inc.
                            Parker Drilling Company North America, Inc.
                            Parker-VSE, Inc.  (formerly Vance Systems
                               Engineering, Inc.)
                            DGH, Inc.
                            Parker Drilling Company International Limited
                            Parker USA Drilling Company (formerly Parcan
                               Limited)
                            Parker Technology, L.L.C.
                            Parker Technology, Inc.
                            Parker Drilling U.S.A. Ltd.
                            Parker Drilling Offshore Corporation (formerly
                               Hercules Offshore Corporation)
                            Parker Drilling Offshore International, Inc.


                            By:    /s/ David W. Tucker
                               ------------------------------------------------
                            Name:  David W. Tucker
                            Its:   Vice President & Treasurer

                            Quail Tools, L.L.P.

                            By:    /s/ James J. Davis
                               ------------------------------------------------
                            Name:  James J. Davis
                            Its:   Vice President & Treasurer

                            Parker Drilling Offshore USA, L.L.C. (formerly
                               Mallard Bay Drilling, L.L.C.)


                            By:    /s/ Bruce J. Korver
                               ------------------------------------------------
                            Name:  Bruce J. Korver
                            Its:   Vice President-Finance



                            NEW GUARANTORS:

                            Anachoreta, Inc.
                            Pardril, Inc.
                            Parker Aviation, Inc.
                            Parker Drilling (Kazakhstan), Ltd.
                            Parker Drilling Company of Niger
                            Parker North America Operations, Inc.
                            Selective Drilling Corporation
                            Universal Rig Service Corp.


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                            By: /s/ David W. Tucker
                               ------------------------------------------
                            Name:  David W. Tucker
                            Its:   Vice President & Treasurer


                            Parker Drilling Management Services, Inc.
                            Creek International Rig Corp.


                            By: /s/ Bruce J. Korver
                               ------------------------------------------
                            Name:  Bruce J. Korver
                            Its:   Vice President & Treasurer


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