<PAGE>   1
 
                                                                  EXHIBIT 3.1(i)
 
                          CERTIFICATE OF INCORPORATION
                                       OF
                           G.D.E. SEARCH CORPORATION
 
                              A STOCK CORPORATION
 
          FIRST: The name of this Corporation is G.D.E. Search Corporation.
 
          SECOND: Its Registered Office in the state of Delaware is to be
     located at 3422 Old Capitol Trail, Suite 700, in the City of Wilmington,
     County of New Castle, Zip Code 19808-6192. The Registered Agent in charge
     thereof DELAWARE BUSINESS INCORPORATORS, INC., located at same address, as
     above.
 
          THIRD: The purpose of the corporation is to engage in any lawful act
     or activity for which corporations may be organized under the General
     Corporation Law of Delaware.
 
          FOURTH: The amount of the total authorized capital stock of this
     corporation is 50,000,000 shares of $.0001 par value.
 
          FIFTH: The name and mailing address of the incorporator are as
     follows:
 
                NAME             Lori M. Smith
              MAILING ADDRESS 3422 Old Capitol Trail, Suite 700
                                Wilmington, Delaware     ZIP CODE 19808-6192
 
          SIXTH: The powers of the incorporator are to terminate upon the filing
     of the certificate of incorporation. The name and mailing address of the
     person who is to serve as director until the first annual meeting of the
     shareholders or until their successors are duly elected and qualify is as
     follows:
 
                NAME             Arthur A. Graves, III
              MAILING ADDRESS 701 S. Parker Street, Suite 7300
                                Orange, California     ZIP CODE 92668
 
THE UNDERSIGNED, for the purpose of forming a corporation under the laws of the
State of Delaware, make, file and record this Certificate, and do certify that
the facts herein stated are true, and have accordingly hereunto set my hand this
31st day of January, A.D. 1989.
 
                                            /S/  LORI M. SMITH
<PAGE>   2
 
                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION
 
     IT IS HEREBY CERTIFIED THAT:
 
     The name of the corporation is G.D.E. SEARCH CORPORATION (the
"Corporation").
 
     1. The applicable section amended by this Certificate of Amendment of
Certificate of Incorporation presently reads as follows:
 
          "FOURTH: The amount of the total authorized capital stock of this
     corporation is 50,000,000 shares of $.0001 par value."
 
     The Company's Amended Certificate of Incorporation shall be amended to read
as follows:
 
          "FOURTH: The amount of the total authorized capital stock of this
     corporation is 50,000,000 shares of $.00001 par value."
 
     2. The applicable section amended by this Certificate of Amendment of
Certificate of Incorporation presently reads as follows:
 
          "SIXTH: The powers of the incorporator are to terminate upon the
     filing of the Certificate of Incorporation. The name and mailing address of
     the person who is to serve as director until the first annual meeting of
     the shareholders or until their successors are duly elected and qualify is
     as follows:
 
<TABLE>
<S>       <C>
Name:     Arthur A. Graves, III
Address:  701 S. Parker Street, Suite 7300
          Orange, CA 92668"
</TABLE>
 
     The Corporation's Amended Certificate of Incorporation shall be amended to
read as follows:
 
          "SIXTH: The powers of the incorporator terminate upon the filing of
     the Certificate of Incorporation. The name and mailing address of the
     Chairman of the Board is as follows:
 
<TABLE>
<S>       <C>
Name:     Robert P. Jackson
Address:  4200 South Hulen Street
          Suite 536
          Fort Worth, Texas 76109"
</TABLE>
 
     3. That pursuant to resolution of its Board of Directors, a special meeting
of the stockholders of said corporation was duly called and held, upon notice in
accordance with Section 222 of the General Corporation Law of the State of
Delaware at which meeting the necessary number of shares as required by statute
were voted in favor of the amendments.
 
     4. That said amendments were duly adopted in accordance with the provisions
of Section 242 of the General Corporation Law of the State of Delaware.
 
     IN WITNESS WHEREOF, said G.D.E. SEARCH CORPORATION has caused its corporate
seal to be hereunto affixed and this Certificate to be signed by Robert P.
Jackson, its President and G. Don Edwards, its Secretary, this 21st day of
March, 1989.
 
                                                /S/  ROBERT P. JACKSON
                                            ------------------------------------
                                                     Robert P. Jackson
 
                                            ATTEST:
 
                                                 /S/  G. DON EDWARDS
                                            ------------------------------------
                                                      G. Don Edwards
<PAGE>   3
 
                            CERTIFICATE OF AMENDMENT
                                       TO
                          CERTIFICATE OF INCORPORATION
                                       OF
                           G.D.E. SEARCH CORPORATION
 
     Pursuant to the provisions of Section 242 of the Delaware General
Corporation Law, the undersigned corporation hereby certifies the adoption of
the following Certificate of Amendment to its Certificate of Incorporation.
 
     FIRST: The name of the corporation is G.D.E. SEARCH CORPORATION.
 
     SECOND: The following amendments of the Articles of Incorporation were duly
adopted in the manner prescribed by Section 242 of the Delaware General
Corporation Law with written consent of the stockholders given in accordance
with Section 228 of the Delaware General Corporation Law:
 
          Article FIRST of the Certificate of Incorporation is hereby amended to
     read as follows:
 
             FIRST: The name of the Corporation is PONDER INDUSTRIES, INC.
 
          Article FOURTH of the Certificate of Incorporation is hereby amended
     to read as follows:
 
             FOURTH: The total number of shares of stock which this Corporation
                     shall have the authority to issue shall be 50,000,000
                     shares of common stock of the par value of $.01 per share.
 
                     Each four shares of the Corporation's common stock, $.00001
                     par value per share, outstanding and to be outstanding
                     pursuant to this Corporation's Stock Bonus Plan, shall be
                     and they are hereby automatically changed (without any
                     further act) into one share of common stock, $.01 par value
                     per share, provided that no fractional shares shall be
                     issued. Fractional share interests of .5 or more shall be
                     rounded to the next full share and fractional share
                     interests of less than .5 shall be eliminated. Immediately
                     after the effective date of this amendment, the
                     stockholders of record as of the close of business on the
                     effective date shall be given notice to surrender their
                     certificates of shares of common stock, $.00001 par value,
                     to the Corporation for cancellation and reissue in
                     accordance with the terms of the foregoing.
 
                                            G.D.E. SEARCH CORPORATION
 
                                            By:   /S/  ROBERT P. JACKSON
                                              ----------------------------------
                                                      Robert P. Jackson
 
                                            ATTEST:
 
                                                  /S/  C. DIANE WELLS
                                            ------------------------------------
                                                       C. Diane Wells
                                                         Secretary
 
Dated: January 26, 1990
<PAGE>   4
 
                             CERTIFICATE OF MERGER
                                       OF
                            PONDER INDUSTRIES, INC.
                          INTO PONDER INDUSTRIES, INC.
 
     Under Section 252 of the General Corporation Law of the State of Delaware,
Ponder Industries, Inc. hereby certifies that:
 
          1. The name and state of incorporation of each of the constituent
     corporations are:
 
             a. Ponder Industries, Inc., a Texas corporation.
 
             b. Ponder Industries, Inc., a Delaware corporation.
 
          2. An Agreement and Plan of Merger has been approved, adopted,
     certified, executed and acknowledged by each of the constituent
     corporations in accordance with the provisions of subsection (c) of Section
     252 of the General Corporation Law of the State of Delaware.
 
          3. The name of the surviving corporation is Ponder Industries, Inc., a
     Delaware corporation.
 
          4. The executed Agreement and Plan of Merger is on file at the
     principal place of business of the surviving corporation at 5005 Riverway
     Drive, Suite 550, Houston, Texas 77056.
 
          5. A copy of the Agreement and Plan of Merger will be furnished by the
     surviving corporation on request and without cost, to any stockholder of
     Ponder Industries, Inc., a Texas corporation or Ponder Industries, Inc., a
     Delaware corporation.
 
          6. The authorized capital stock of the non-surviving corporation,
     which is incorporated under the laws of the State of Texas, is 4,200,000
     shares of common stock, no par value.
 
          7. The Certificate of Incorporation of Ponder Industries, Inc. shall
     be its Certificate of Incorporation.
 
     IN WITNESS WHEREOF, Ponder Industries, Inc. has caused this certificate to
be signed by its President, and attested by its Secretary, on the 2nd day of
December, 1997, to be effective October 12, 1990.
 
                                            PONDER INDUSTRIES, INC.
 
                                            By:    /S/  EUGENE L. BUTLER
                                              ----------------------------------
                                                       Eugene L. Butler
                                              President, Chief Executive Officer
                                                    and Chairman of the Board
 
                                            ATTEST:
 
                                            By:   /S/  DEBORAH S. HUDGEONS
                                              ----------------------------------
                                              Name: Deborah S. Hudgeons
                                              Title: Office Manager
<PAGE>   5
 
                            CERTIFICATE OF AMENDMENT
                                       OF
                          CERTIFICATE OF INCORPORATION
                                       OF
                            PONDER INDUSTRIES, INC.
 
     The undersigned, Ponder Industries, Inc., a Delaware corporation (the
"Corporation"), for the purpose of amending the Certificate of Incorporation of
the Corporation, in accordance with the General Corporation Law of the State of
Delaware, does hereby make and execute this Certificate of Amendment of
Certificate of Incorporation and does hereby certify that:
 
          FIRST: The following resolutions proposed by the Board of Directors
     and adopted by the stockholders of the Corporation set forth the amendments
     adopted:
 
             RESOLVED, that the Certificate of Incorporation of the Company be
        amended by deleting all of the present Article Fourth and inserting in
        lieu thereof the following Article Fourth:
 
                FOURTH. The total number of shares of stock which the
           Corporation shall have authority to issue is 160,000,000 shares, of
           which 150,000,000 shares shall be common stock, $.01 par value per
           share, and 10,000,000 shares shall be preferred stock, $.01 par value
           per share. The designations, rights, preferences, privileges and
           voting powers of the preferred stock, and any restrictions and
           qualifications thereof, shall be determined by the Board of
           Directors.
 
             RESOLVED, that the Certificate of Incorporation of the Company be
        amended by deleting all of the present Article Sixth and inserting in
        lieu thereof the following Article Sixth:
 
                SIXTH. No director of the Corporation shall be liable to the
           Corporation or any of its stockholders for monetary damages for
           breach of fiduciary duty as a director; provided that this Article
           SIXTH shall not eliminate or limit the liability of a director of the
           Corporation; (i) for any breach of the director's duty of loyalty to
           the Corporation or its stockholders, (ii) for acts or omissions not
           in good faith or that involve intentional misconduct or a knowing
           violation of law, (iii) under Section 174 of the General Corporation
           Law of the State of Delaware, or (iv) for any transaction from which
           the director derived an improper personal benefit.
 
                SECOND: Such amendments were duly adopted in accordance with the
           provisions of Section 242 of the General Corporation Law of the State
           of Delaware, as amended.
 
     IN WITNESS WHEREOF, this Certificate of Amendment has been executed on
behalf of the Corporation by its President on this 21st day of May 1998.
 
                                            PONDER INDUSTRIES, INC.
 
                                            By:    /S/  EUGENE L. BUTLER
                                              ----------------------------------
                                                      Eugene L. Butler,
                                                          President