EXHIBIT 10.11.6


               SIXTH AMENDMENT TO FIFTH RESTATED CREDIT AGREEMENT

      This Sixth  Amendment  to Fifth  Restated  Credit  Agreement  (this "SIXTH
AMENDMENT") is entered into as of the 19th day of May, 1997, by and among Snyder
Oil Corporation  ("BORROWER"),  NationsBank of Texas,  N.A., as Agent ("AGENT"),
and NationsBank of Texas,  N.A.  ("NATIONSBANK"),  Bank One, Texas,  N.A. ("BANK
ONE"),  Wells Fargo Bank,  N.A.  ("WELLS  FARGO"),  Texas Commerce Bank National
Association  ("TCB," and together  with  NationsBank,  Bank One and Wells Fargo,
collectively referred to herein as the "ORIGINAL BANKS") and Credit Lyonnais New
York Branch as Banks (the "BANKS").

                               W I T N E S E T H:

      WHEREAS,  the Banks,  Borrower and Agent are parties to that certain Fifth
Restated Credit  Agreement dated as of June 30, 1994, as amended by that certain
(i) letter  agreement by and among  Borrower and the Original  Banks dated as of
May 1, 1995,  (ii) Second  Amendment to Fifth Restated  Credit  Agreement by and
among  Borrower,  Agent and the Original Banks dated as of June 30, 1995,  (iii)
Third Amendment to Fifth Restated Credit Agreement by and among Borrower,  Agent
and the Original  Banks dated as of November 1, 1995,  (iv) Fourth  Amendment to
Fifth Restated Credit Agreement by and among Borrower,  Agent and Original Banks
dated as of April 4, 1996,  and (v) Fifth  Amendment  to Fifth  Restated  Credit
Agreement  by and among  Borrower,  Agent  and the  Original  Banks  dated as of
November 1, 1996 (as amended,  the "CREDIT AGREEMENT") (unless otherwise defined
herein,  all terms used herein with their initial letter  capitalized shall have
the meaning given such terms in the Credit Agreement); and

      WHEREAS,  pursuant to the Credit  Agreement,  the Banks have made  certain
Loans to Borrower,  and Agent has issued certain  Letters of Credit on behalf of
Borrower; and

      WHEREAS,  Borrower  has advised the Banks that  Borrower  intends to issue
certain  ten  year   non-amortizing   Senior  Subordinated  Notes  (the  "SENIOR
SUBORDINATED NOTES"), in an aggregate principal amount up to $200,000,000;  such
Senior  Subordinated  Notes being more  particularly  described  in that certain
Preliminary Prospectus Supplement (To Prospectus Dated August 4, 1994) dated May
__, 1997, a copy of which has been delivered to each Bank; and

      WHEREAS,  Borrower has requested  that the Credit  Agreement be amended in
certain  respects  in  connection  with the  proposed  issuance  of such  Senior
Subordinated Notes; and

      WHEREAS,  subject to the terms and conditions herein contained,  the Banks
have agreed to Borrower's requests.

      NOW  THEREFORE,  for and in  consideration  of the  mutual  covenants  and
agreements  herein  contained  and other good and  valuable  consideration,  the
receipt  and  sufficiency  of  which  are  hereby  acknowledged  and  confessed,
Borrower, Agent and each Bank hereby agree as follows:



      SECTION 1.  AMENDMENTS.  Subject  to the  satisfaction  of each  condition
precedent set forth in SECTION 3 hereof and in reliance on the  representations,
warranties,  covenants and  agreements  contained in this Sixth  Amendment,  the
Credit Agreement shall be amended  effective May __, 1997 (the "EFFECTIVE DATE")
in the manner provided in this SECTION 1.

     1.1.  AMENDMENT  TO  DEFINITIONS.  The  definition  of  "Loan  Papers"  and
"Restricted  Payment"  contained in Section 1.1 of the Credit Agreement shall be
amended to read in full as follows:

            "Loan Papers" means this Agreement, the Letter Agreement, the Second
      Amendment, the Third Amendment, the Fourth Amendment, the Fifth Amendment,
      the Sixth Amendment,  the Notes, the Mortgages,  the Restricted Subsidiary
      Guarantees and all other certificates,  documents or instruments delivered
      in connection  with this  Agreement,  as the foregoing may be amended from
      time to time.

            "Restricted Payment" means (a) any Distribution by Borrower, (b) any
      capital  contribution,  loan or  advance  by  Borrower  or any  Restricted
      Subsidiary to any Unrestricted Subsidiary of Borrower, (c) the issuance of
      a Guarantee by Borrower or any Restricted  Subsidiary  with respect to any
      Debt  or  other  obligation  of  any  Unrestricted  Subsidiary,   (d)  the
      retirement,  redemption or prepayment  prior to the scheduled  maturity by
      Borrower or a Restricted Subsidiary of Debt of Borrower or such Restricted
      Subsidiary  which is subordinate  to the  Obligations,  including  without
      limitation,  the Fourth Debentures and the Convertible Debentures (and, in
      the case of the Third  Convertible  Debentures and the Fourth  Debentures,
      any redemption  payments  required as a result of any asset sale or change
      of  control),  and (e) any  Investment  by  Borrower  which is a Permitted
      Investment  pursuant to  subsection  (e) of the  definition  of  Permitted
      Investment.  For purposes of this definition,  at the time Borrower or any
      Restricted Subsidiary issues any Guarantee of any Debt or other obligation
      of any  Unrestricted  Subsidiary,  Borrower or such Restricted  Subsidiary
      will be deemed to have made a Restricted Payment in an amount equal to the
      maximum  potential  liability  of Borrower or such  Restricted  Subsidiary
      under such Guarantee (not to exceed,  however,  the aggregate  outstanding
      Debt   [including   accrued  but  unpaid  interest  and  fees]  and  other
      obligations which are guaranteed pursuant to any such Guarantee).

     1.2. ADDITIONAL  DEFINITIONS.  Section 1.1 of the Credit Agreement shall be
amended to add the following definitions to such Section:

            "Draft  Prospectus"  means  that  certain   Preliminary   Prospectus
      Supplement (To Prospectus  Dated August 4, 1994) dated May __, 1997, which
      is in draft  form and  subject  to  completion,  a copy of which  has been
      previously provided by Borrower to the Banks.

                                        2



            "Fourth Debentures" means Borrower's Senior Subordinated Notes in an
      aggregate  amount  not to exceed  $200,000,000  and which  shall be on the
      terms and conditions set forth in the Draft Prospectus.

            "Fourth Indenture Trustee" means Texas Commerce Bank National
      Association and any successor trustee appointed pursuant to the Fourth
      Indenture.

            "Fourth  Indenture"  means an Indenture  entered into by and between
      Borrower and the Fourth  Indenture  Trustee setting forth certain terms of
      the Fourth Debentures and which shall contain the terms and conditions set
      forth in the Draft Prospectus.

            "Sixth  Amendment"  means  that  certain  Sixth  Amendment  to Fifth
      Restated  Credit  Agreement  dated  as of May  ___,  1997,  by  and  among
      Borrower, Agent and the Banks.

     1.3. DEBT COVENANT. Section 9.1 of the Credit Agreement shall be amended to
read in full as follows:

            SECTION  9.1.  TOTAL  ADDITIONAL  DEBT OF  BORROWER  AND  RESTRICTED
      SUBSIDIARIES.  Neither  Borrower nor any Restricted  Subsidiary will incur
      any Debt other than (a) Debt secured by Permitted  Encumbrances  described
      in  subpart  (1)  of  the  definition  of  Permitted   Encumbrances,   (b)
      Nonrecourse  Debt, (c) Third Party Letters of Credit  permitted by SECTION
      2.1 hereof,  (d) the Loans,  (e) margin  accounts with brokers and dealers
      relating to Margin Stock and other securities,  and (f) Guarantees of Debt
      and other  liabilities of other  Restricted  Subsidiaries  and of Borrower
      provided that such Debt and other  liabilities  are permitted  pursuant to
      this  Agreement;  PROVIDED,  THAT, the Debt permitted  pursuant to SECTION
      9.1(A) and (B) shall not exceed  $15,000,000 in the  aggregate;  PROVIDED,
      FURTHER THAT, the Third Party Letter of Credit Exposure under Cash Secured
      Third Party  Letters of Credit  shall not exceed at any time five  percent
      (5%) of the Borrowing Base in effect at such time;  and PROVIDED,  FURTHER
      THAT,  the maximum  aggregate  outstanding  balance of Borrower's  and its
      Subsidiaries'  margin  accounts  shall  not  exceed  one  percent  (1%) of
      Borrower's Consolidated Tangible Net Worth at any time. In addition to the
      foregoing,  Borrower may issue (i) the Second  Convertible  Debentures  in
      exchange  for the  Second  Preferred  Stock,  (ii) the  Third  Convertible
      Debentures,  and (iii) the Fourth  Debentures  provided that (A) the Third
      Convertible  Debentures are called for redemption within 30 days following
      issuance of the Fourth Debentures, and (B) the proceeds of the issuance of
      the Fourth  Debentures are used, in part and within 90 days following such
      issuance,  to redeem the Third Convertible  Debentures in full;  provided,
      that  Borrower  shall give each Bank  ninety (90) days  advance  notice of
      Borrower's  intention to complete any exchange of  Convertible  Debentures
      for Preferred  Stock,  and if Majority Banks require that Borrower and the
      Restricted  Subsidiaries  grant Liens on their oil and gas  properties and
      Related Assets pursuant

                                        3

      to SECTION  5.1(B),  Borrower will not complete  such  exchange  until all
      requisite  Mortgages  have been executed and delivered by Borrower and the
      Restricted  Subsidiaries  and Agent has  notified  Borrower  that all such
      Mortgages have been filed of record and that all other steps  necessary to
      perfect (and confirm  perfection)  of the Liens created by such  Mortgages
      have been taken.

     1.4.  RESTRICTED  PAYMENTS  COVENANT.  Section 9.2 of the Credit  Agreement
shall be amended to read in full as follows:

            SECTION  9.2.   RESTRICTED   PAYMENTS.   Neither  Borrower  nor  any
      Restricted  Subsidiary  will  declare  or  make  any  Restricted  Payment;
      provided, that, so long as no Default or Event of Default,  Borrowing Base
      Deficiency  or  noncompliance  with  SECTION 10.4 exists  (without  giving
      effect to the cure periods  provided by SECTION 4.4 or 10.4), and provided
      further that no Default or Event of Default,  Borrowing Base Deficiency or
      non compliance with SECTION 10.4 would result from such Restricted Payment
      (without  giving  effect to the cure  periods  provided  by SECTION 4.4 or
      10.4),  Borrower  and  Restricted  Subsidiaries  may (a)  make  Restricted
      Payments in an aggregate  amount  (measured  cumulatively  from January 1,
      1996) not to exceed the sum of the  following (i)  $75,000,000,  plus (ii)
      the net cash proceeds to Borrower from all equity  offerings  completed by
      Borrower of Borrower's equity securities after January 1, 1996, plus (iii)
      all cash  Distributions  actually  received by Borrower or any  Restricted
      Subsidiary from Unrestricted Subsidiaries after January 1, 1996, plus (iv)
      fifty  percent  (50%) of  Borrower's  Consolidated  Cash Flow earned on or
      after January 1, 1996 to the date of determination, (b) declare and make a
      Qualified Redemption of the Second Issue, (c) issue the Second Convertible
      Debentures in exchange for the Second  Preferred Stock, and (d) redeem the
      Third  Convertible  Debentures  with the  proceeds of the  issuance of the
      Fourth Debentures.

     1.5. AMENDMENTS TO MATERIAL COVENANTS.  SECTION 9.6 of the Credit Agreement
shall be amended to read in full as follows:

            SECTION 9.6. AMENDMENTS TO MATERIAL DOCUMENTS.  Neither Borrower nor
      any Restricted  Subsidiary shall enter into or permit any modifications or
      amendment  of, or waive any  material  right or  obligation  of any Person
      under, (a) its certificate or articles of  incorporation,  bylaws or other
      organizational  document other than amendments,  modifications and waivers
      which are not, individually or in the aggregate,  material,  (b) the First
      Preferred Stock Designation,  the Second Preferred Stock Designation,  the
      First Indenture,  the Second  Indenture,  the Third Indenture,  the Fourth
      Indenture, the Convertible Debentures,  or the Fourth Debentures,  (c) the
      DJ Transaction  Documents,  or (d) the Patina Transaction  Documents other
      than,  in  the  case  of  clauses  (c)  and  (d)  preceding,   amendments,
      modifications and waivers which are not,  individually or in the aggregate
      material;  provided,  that  Borrower  shall  provide  Agent  and each Bank
      written notice of each immaterial amendment,

                                        4



      modification  or  waiver  of  any  DJ  Transaction   Documents  or  Patina
      Transaction  Documents  not later  than  fifteen  (15) days after the date
      Borrower  or  its  Restricted   Subsidiary  enters  into  such  amendment,
      modification, or waiver specifying in detail the subject thereof.

     1.6. USE OF PROCEEDS COVENANT. Section 9.7 of the Credit Agreement shall be
amended to read in full as follows:

            SECTION 9.7. USE OF PROCEEDS. The proceeds of Borrowings will not be
      used for any purpose  other than (a) working  capital,  (b) to finance the
      acquisition,  exploration  and  development  of oil and gas properties and
      Related  Assets  and  the  transportation,  processing  and  marketing  of
      hydrocarbons  by Borrower  and  Restricted  Subsidiaries,  (c)  Restricted
      Payments  permitted  pursuant  to SECTION  9.2 and  Investments  permitted
      pursuant to SECTION 9.8 provided,  that none of such proceeds  (including,
      without  limitation,  proceeds of Letters of Credit issued hereunder) will
      be used,  directly or  indirectly,  for the  purpose,  whether  immediate,
      incidental or ultimate,  of  purchasing or carrying any Margin Stock,  and
      none  of  such  proceeds  will be used  in  violation  of  applicable  law
      (including,  without limitation, the Margin Regulations).  Notwithstanding
      anything to the contrary contained herein,  from and after the issuance of
      the Fourth  Debentures and continuing  until the next  Determination  Date
      thereafter, the proceeds of any Borrowing (any "proposed Borrowing") which
      is made at any time  when the sum of (a) the  aggregate  Letter  of Credit
      Exposure  of all Banks at such time,  plus (b) the  aggregate  outstanding
      principal   balance  of  all  Loans  at  such  time   (collectively,   the
      "outstanding   credit")   exceeds   Seventy  Million  and  No/100  Dollars
      ($70,000,000)  (such  computation  to be made after giving  effect to such
      proposed  Borrowing)  shall, to the extent the outstanding  credit exceeds
      Seventy  Million and No/100 Dollars  ($70,000,000)  after giving effect to
      such  proposed  Borrowing,  be used only by  Borrower  and its  Restricted
      Subsidiaries  and only to finance  substantially  contemporaneous  capital
      expenditures for the  acquisition,  exploration and development of oil and
      gas properties and the acquisition and improvement of Related Assets.

      SECTION 2. MANDATORY  REDUCTIONS IN BORROWING BASE. Borrower  acknowledges
and agrees that notwithstanding  anything to the contrary contained herein or in
the Credit Agreement, simultaneously with the issuance of the Senior Subordinate
Notes,  the Total Borrowing Base then in effect under the Credit  Agreement will
reduce by eighty  percent (80%) of the amount by which the  aggregate  principal
amount of the Senior  Subordinate Notes so issued exceeds  $150,000,000.  All of
such reduction shall be allocated to the Borrowing Base for Facility A. Borrower
shall be required to immediately make a mandatory prepayment of principal of the
Facility  A Notes in an  amount  sufficient  to  eliminate  any  Borrowing  Base
Deficiency resulting from such reduction. Borrower acknowledges that the maximum
amount of Senior  Subordinate  Notes  Borrower is  permitted  to issue under the
Credit Agreement is $200,000,000.

                                        5



      SECTION 3.  CONDITIONS  PRECEDENT  TO  EFFECTIVENESS  OF  AMENDMENTS.  The
amendments  to the  Credit  Agreement  contained  in  SECTION  1 of  this  Sixth
Amendment shall be effective only upon, and are  conditioned  upon, the delivery
to Agent and each Bank of such resolutions,  certificates and other documents as
Agent  or  any  Bank  shall  request  relative  to the  Note  Issuance  and  the
authorization,  execution and delivery by Borrower of this Sixth  Amendment.  If
the foregoing condition has not been satisfied by the Effective Date, this Sixth
Amendment and all obligations of the Banks and Agent contained  herein shall, at
the option of Majority Banks, terminate.

      SECTION 4. REDESIGNATION OF CERTAIN SUBSIDIARIES. Notwithstanding anything
to the contrary contained herein or in the Credit Agreement, Borrower, Agent and
each Bank hereby  acknowledge and agree that, from and after the Effective Date,
(i) Snyder Acquisition  Corporation,  (ii) Institutional  Services,  Inc., (iii)
SOCO Thomasville, Inc. and the Subsidiaries of SOCO Thomasville, Inc., (iv) SOCO
California Properties,  Inc., and (v) SOCO Technologies,  Inc. (the Subsidiaries
listed in clauses (i) through (v) above are  collectively  referred to herein as
the "REDESIGNATED  SUBSIDIARIES"),  shall each be automatically  redesignated as
Unrestricted  Subsidiaries  for purposes of the Credit  Agreement  and the other
Loan Papers  without the  necessity  of any further act on the part of Borrower,
Agent,  any such  Redesignated  Subsidiary or any Bank.  In connection  with the
foregoing,  Banks  and  Agent  hereby  release  and  discharge  (a)  each of the
Redesignated  Subsidiaries  from all  obligations and liabilities of each under,
and with respect to, that certain Amended and Restated Guaranty dated as of July
1, 1993 (as  amended  through  the date  hereof),  and (b) the Liens in favor of
Agent  encumbering  the capital stock of each  Redesignated  Subsidiary  pledged
under, and pursuant to, that certain Amended and Restated Pledge Agreement dated
as of July 1, 1993 (as  amended  through the date  hereof),  and Agent is hereby
authorized to execute,  deliver and file of record appropriate  releases of such
Liens and to take such  other  action as shall be  necessary  to  evidence  such
release,  including,   without  limitation,  the  release  to  Borrower  of  all
certificates in Agent's possession evidencing the issued and outstanding capital
stock of each Redesignated Subsidiary.

      SECTION 5. REPRESENTATIONS AND WARRANTIES OF BORROWER. To induce the Banks
and Agent to enter into this Sixth  Amendment,  Borrower  hereby  represents and
warrants to Agent as follows:

      5.1 Each  representation  and  warranty  of Borrower  and each  Restricted
Subsidiaries contained in the Credit Agreement and the other Loan Papers is true
and correct on the date hereof and will be true and correct  after giving effect
to the amendments set forth in SECTION 1 hereof.

      5.2 The  execution,  delivery  and  performance  by Borrower of this Sixth
Amendment are within the Borrower's  corporate powers, have been duly authorized
by necessary action,  require no action by or in respect of, or filing with, any
governmental body, agency or official and do not violate or constitute a default
under any provision of  applicable  law or any Material  Agreement  binding upon
Borrower or the Subsidiaries of Borrower or result in the creation or imposition
of any Lien upon any of the assets of Borrower or the  Subsidiaries  of Borrower
except Permitted Encumbrances.

                                        6



      5.3 This Sixth Amendment  constitutes the valid and binding  obligation of
Borrower   enforceable  in  accordance  with  its  terms,   except  as  (i)  the
enforceability thereof may be limited by bankruptcy,  insolvency or similar laws
affecting  creditor's rights  generally,  and (ii) the availability of equitable
remedies may be limited by equitable principles of general application.

      5.4 (a) The  aggregate  fair  market  value  of all  assets  owned  by the
Redesignated  Subsidiaries (taken as a whole) as of the date hereof is less than
$1,000,000,  and (b) the aggregate amount of Consolidated Cash Flow attributable
to the Redesignated  Subsidiaries  (taken as a whole) during the four (4) fiscal
quarters immediately preceding the date hereof is less than $1,000,000.

      SECTION 6.        MISCELLANEOUS.

      6.1 NO DEFENSES. Borrower hereby represents and warrants to the Banks that
there are no  defenses  to  payment,  counterclaims  or rights of  set-off  with
respect to the Loans existing on the date hereof.

      6.2  REAFFIRMATION OF LOAN PAPERS;  EXTENSION OF LIENS. Any and all of the
terms and provisions of the Credit  Agreement and the Loan Papers shall,  except
as amended and modified hereby, remain in full force and effect. Borrower hereby
extends the Liens securing the Obligations  until the Obligations have been paid
in full, and agrees that the amendments and modifications herein contained shall
in no manner affect or impair the Obligations or the Liens securing  payment and
performance thereof.

      6.3 PARTIES IN  INTEREST.  All of the terms and  provisions  of this Sixth
Amendment  shall bind and inure to the benefit of the  parties  hereto and their
respective successors and assigns.

      6.4 LEGAL EXPENSES. Borrower hereby agrees to pay on demand all reasonable
fees and expenses of counsel to Agent incurred by Agent,  in connection with the
preparation,  negotiation  and execution of this Sixth Amendment and all related
documents.

      6.5  COUNTERPARTS.  This Sixth Amendment may be executed in  counterparts,
and all parties need not execute the same counterpart;  however,  no party shall
be bound by this Sixth  Amendment until all parties have executed a counterpart.
Facsimiles shall be effective as originals.

      6.6   COMPLETE AGREEMENT.  THIS SIXTH AMENDMENT, THE CREDIT AGREEMENT
AND THE OTHER LOAN PAPERS REPRESENT THE FINAL AGREEMENT BETWEEN THE
PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR,
CONTEMPORANEOUS OR ORAL AGREEMENTS OF THE PARTIES.  THERE ARE NO
UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

      6.7 HEADINGS.  The headings,  captions and arrangements used in this Sixth
Amendment are, unless specified otherwise, for convenience only and shall not be
deemed to limit, amplify or modify the terms of this Sixth Amendment, nor affect
the meaning thereof.

                                        7



      IN WITNESS WHEREOF, the parties hereto have caused this Sixth Amendment to
be duly executed by their  respective  authorized  officers on the date and year
first above written.

                                          BORROWER:

                                          SNYDER OIL CORPORATION,
                                           a Delaware corporation

                                          By:/s/ Peter E. Lorenzen
                                                 Peter E. Lorenzen
                                          Its:Vice President

                                          AGENT:

                                          NATIONSBANK OF TEXAS, N.A.

                                          By:/s/ J.Scott Fowler
                                                 J.Scott Fowler
                                          Its:Vice President

                                          BANKS:

                                          NATIONSBANK OF TEXAS, N.A.

                                          By:/s/ J. Scott Fowler
                                                 J. Scott Fowler
                                          Its:Vice President

                                          TEXAS COMMERCE BANK
                                          NATIONAL ASSOCIATION

                                          By:/s/ Dale S. Hurd
                                                 Dale S. Hurd
                                          Its:Senior Vice President

                                           BANK ONE, TEXAS, N.A.

                                          By:/s/ Brad Bartek
                                                 Brad Bartek
                                          Its:Vice President

                                        8



                                            WELLS FARGO BANK, N.A.

                                          By:/s/ Chad Kirkham
                                                 Chad Kirkham
                                          Its:Vice President

                                          CREDIT LYONNAIS NEW YORK BRANCH

                                          By:/s/ Jacques-Yves Mulliez
                                                 Jacques-Yves Mulliez
                                          Its:Senior Vice President
1/234135.4


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