EXHIBIT 10.1

<PAGE>


                               SECOND AMENDMENT TO
                     SEITEL, INC. REVOLVING CREDIT AGREEMENT


     This Second Amendment to Seitel,  Inc.  Revolving Credit Agreement dated as
of May 1, 1997 (this  "Second  Amendment")  is among  Seitel,  Inc.,  a Delaware
corporation  (the  "Borrower"),  the  lenders set forth on the  signature  pages
hereto (the "Lenders") and The First National Bank of Chicago,  individually and
as agent for the Lenders (in such capacity, the "Agent").

     FOR  VALUABLE  CONSIDERATION,  the receipt and adequacy of which are hereby
acknowledged, the parties hereto agree as follows:

     1.  DEFINITIONS.  Unless  amended  pursuant  hereto or unless  the  context
otherwise  requires,  all terms used herein  which are defined in the  Revolving
Credit Agreement dated as of July 22, 1996, as amended (the "Credit  Agreement")
among the Borrower,  the Agent and the Lenders shall have the meanings  assigned
to them in the Credit Agreement.

     2. AMENDMENTS.  Upon the satisfaction of the conditions precedent set forth
in Section 4 of this Second  Amendment  and  effective  as of the date first set
forth above (the  "Effective  Date"),  the Credit  Agreement shall be amended as
follows:

          (a) The  Commitment  of The First  National  Bank of Chicago is hereby
     increased to $30,000,000.

          (b) The  Commitment of Bank One,  Texas,  N.A. is hereby  increased to
     $20,000,000.

          (c) Exhibit "B" to the Credit  Agreement is hereby amended by deleting
     the amount  "$25,000,000"  on the first page thereof and  replacing it with
     the amount "$50.000.000".

          (d) Schedule 6 to the Credit  Agreement  is hereby  amended to read in
     its entirety asset forth in Schedule 6 attached hereto.

     3. REPRESENTATIONS AND WARRANTIES. The Borrower hereby confirms,  reaffirms
and restates as of the date hereof the  representations and warranties set forth
in  Article V of the  Credit  Agreement,  PROVIDED  that,  with  respect  to the
representations  and  warranties  set forth in Section 5.15,  the  references to
"July 15, 1996" therein shall be deemed to read "May 1, 1997."

     4. CONDITIONS  PRECEDENT.  This Second  Amendment and the amendments to the
Credit  Agreement  provided for in Section 2 hereof shall become effective as of
the Effective  Date when all of the following  conditions  precedent  shall have
been satisfied:

          (a)  The  Agent  shall  have  received  counterparts  of  this  Second
     Amendment  duly  executed  and  delivered by the Borrower and by all of the
     Lenders and consented to by all of the Subsidiary Guarantors.



<PAGE>


          (b) The Agent shall have  received from the Borrower new Ratable Notes
     payable  to the  order  of each  Lender  in the  amount  of  such  Lender's
     Commitment as revised hereby and new  Competitive  Bid Notes payable to the
     order of each  Lender  substantially  in the form of Exhibit "B" as amended
     hereby, each duly executed and delivered by the Borrower.

          (c) The Agent shall have received from the Borrower a certificate of a
     Senior Financial  Officer attaching and certifying  resolutions  adopted by
     the Board of Directors of the  Borrower on or prior to the  Effective  Date
     authorizing  the Borrower to borrow money pursuant to the Credit  Agreement
     from  time  to time  in an  aggregate  principal  amount  at any  one  time
     outstanding  not  in  excess  of  $50,000,000,  and  certifying  that  such
     resolutions  remain in full force and effect and have not been  modified or
     rescinded or attaching and  certifying,  if  applicable,  any amendments to
     such resolutions.

          (d) On the Effective Date and after giving effect to the terms of this
     Second  Amendment,  no Default or Unmatured Default shall have occurred and
     be continuing.

     5. EFFECT ON THE CREDIT  AGREEMENT.  Except to the extent of the amendments
expressly provided for herein, all of the  representations,  warranties,  terms,
covenants and conditions of the Loan Documents (a) shall remain  unaltered,  (b)
shall  continue to be, and shall remain,  in full force and effect in accordance
with their  respective  terms,  and (c) are hereby ratified and confirmed in all
respects. Upon the effectiveness of this Second Amendment, all references in the
Credit  Agreement  (including  references in the Credit  Agreement as amended by
this Second Amendment) to "this Agreement" (and all indirect  references such as
"hereby",  "herein",  "hereof" and "hereunder") shall be deemed to be references
to the Credit Agreement as amended by this Second Amendment.

     6. ENTIRE AGREEMENT. This Second Amendment, the Credit Agreement as amended
by this  Second  Amendment  and the  other  Loan  Documents  embody  the  entire
agreement and  understanding  among the parties hereto and supersede any and all
prior agreements and  understandings  between the parties hereto relating to the
subject matter hereof.

     7. APPLICABLE LAW. THIS SECOND AMENDMENT SHALL BE GOVERNED BY AND CONSTRUED
IN ACCORDANCE WITH THE INTERNAL LAWS (AND NOT THE LAW OF CONFLICTS) OF THE STATE
OF ILLINOIS, BUT GIVING EFFECT TO FEDERAL LAWS APPLICABLE TO NATIONAL BANKS.

     8.  HEADINGS.  The  headings,  captions  and  recitals  used in this Second
Amendment are for convenience  only and shall not affect the  interpretation  of
this Second Amendment.

     9.  COUNTERPARTS.  This Second  Amendment  may be executed in any number of
counterparts,  each of  which  shall be  deemed  an  original,  but all of which
together shall constitute one and the same instrument.



                                     Page 2


<PAGE>

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


                                  SEITEL, INC.


                                  By:         /s/ Debra D. Valice
                                              ---------------------------------
                                  Title:      Senior Vice President
                                              ---------------------------------

                                  THE FIRST NATIONAL BANK OF CHICAGO,
                                  INDIVIDUALLY AND AS AGENT


                                  By:         /s/ Leo Loughead
                                              ---------------------------------
                                  Title:      Corporate Banking Officer
                                              ---------------------------------


                                  BANK ONE, TEXAS, N.A.


                                  By:         /s/ Linda Masera
                                              ---------------------------------
                                  Title:      Vice President
                                              ---------------------------------


























                                     Page 3


<PAGE>


               ACKNOWLEDGMENT AND CONSENT BY SUBSIDIARY GUARANTORS

         Each of the  undersigned  Subsidiary  Guarantors (i)  acknowledges  its
receipt of a copy of and hereby  consents to all of the terms and  conditions of
the foregoing  Second  Amendment and (ii)  reaffirms its  obligations  under the
Subsidiary  Guaranty  dated as of July 22,  1996 in favor of The First  National
Bank of Chicago, as agent.


                            SEITEL DATA CORP.


                            By:         /s/ Barbara J. Steen
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------

                            SEITEL DELAWARE, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            SEITEL MANAGEMENT, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      President
                                        ---------------------------------------


                            SEITEL GEOPHYSICAL, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            DDD ENERGY, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------










                                     Page 4



<PAGE>



                            SEITEL GAS & ENERGY CORP.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            SEITEL POWER CORP.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            SEITEL NATURAL GAS, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            MATRIX GEOPHYSICAL, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            EXSOL, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            DATATEL, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------










                                     Page 5


<PAGE>



                            SEITEL OFFSHORE CORP.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            GEO-BANK, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            ALTERNATIVE COMMUNICATIONS
                            ENTERPRISES, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            SEITEL INTERNATIONAL, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            AFRICAN GEOPHYSICAL, INC.


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------


                            SEITEL DATA LTD.
                            BY:  SEITEL DELAWARE, INC. ITS GENERAL PARTNER


                            By:         /s/ Debra D. Valice
                                        ---------------------------------------
                            Title:      Vice President
                                        ---------------------------------------








                                     Page 6


<PAGE>



                                   SCHEDULE 6
                             INDEBTEDNESS AND LIENS


1.   Note Purchase Agreement dated December 28, 1995,  between Seitel,  Inc. and
     the Series A, Series B and Series C Noteholders relating to Senior Notes in
     the original principal balance of USD 75,000,000.00. As of May 1, 1997, the
     outstanding balance of this debt was USD 75,000,000.00.

2.   Master Equipment Lease Agreement dated March 4, 1994, and related schedules
     between Seitel, Inc. and NationsBanc  Leasing  Corporation  relating to the
     lease by Seitel, Inc. of certain geophysical  computer processing equipment
     and related furniture fixtures in the original amount of USD 324,350.00. As
     of May 1, 1997, the outstanding  balance under this lease was approximately
     USD 134,000.00.

3.   Promissory Note dated July 7, 1995,  between DDD Inc. and CoreStates  Bank,
     N.A.  relating to a term the original  principal  amount of USD  329,701.36
     primarily by certain computer equipment and agreements.  As of May 1, 1997,
     the outstanding of this debt was approximately USD 137,000.00.

4.   Promissory  Note  dated  November  29,  1995,  between  Seitel,   Inc.  and
     CoreStates Bank, N.A.  relating to a term the original  principal amount of
     USD 386,663.62 primarily by a Marathon Coach Bus, and agreements. As of May
     1, 1997, the outstanding of this debt was approximately USD 204,000.00.

5.   Loan and  Security  Agreement  dated as of April 15, 1997 among DDD Energy,
     Inc., Seitel Management,  Inc. and NationsBanc Leasing Corporation of North
     Carolina and related  Secured Term Note A and Secured Term Note B, relating
     to term loans in the aggregate  principal amount of USD 350,553.16  secured
     by  certain  computer  and  telephone  equipment.  As of  May 1,  1997  the
     outstanding balance of this debt was USD 350,533.16.