<PAGE>   1


                                                                    EXHIBIT 4(d)

                          P R 0 M I S S 0 R Y   N 0 T E

$5,200,000.00                                                 December 29, 1995


        FOR VALUE RECEIVED, after date, without grace, in the manner, on the
dates and in the amounts so herein stipulated, the undersigned, ADAMS RESOURCES
EXPLORATION CORPORATION, a Delaware corporation ("Borrower") , PROMISES TO PAY
TO THE ORDER OF NATIONSBANK OF TEXAS, N.A., a national banking association
("Lender"), in Houston, Harris County, Texas, the sum of FIVE MILLION TWO
HUNDRED THOUSAND AND N0/100 DOLLARS ($5,200,000.00) or, if less, the aggregate
unpaid principal amount of advances made by Lender to Borrower pursuant to this
Note, in lawful money of the United States of America, which shall be legal
tender in payment of all debts and dues, public and private, at the time of
payment, and to pay interest on the unpaid principal amount from date until
maturity at the rate or rates described in this Note ("Stated  Rate"), not to
exceed the maximum non-usurious interest rate permitted by applicable law from
time to time in effect as such law may be interpreted, amended, revised,
supplemented or enacted ("Maximum Rate"), provided that if at any time the
Stated Rate exceeds the Maximum Rate then interest hereon shall accrue at the
Maximum Rate. In the event the Stated Rate subsequently decreases to a level
less than the Maximum Rate or if the Maximum Rate applicable to this Note
should subsequently be increased to a level greater than the Stated Rate, then,
in either case, interest hereon shall thereafter accrue at a rate equal to the
applicable Maximum Rate until the aggregate amount of interest accrued through
the term of this Note equals the aggregate amount of interest which would have
accrued at the Stated Rate without regard to any usury limit, at which time
interest hereon shall again accrue at the Stated Rate.

     Accrued and unpaid interest on each LIBOR Loan shall be due and payable on
the last day of the Interest Period with respect to such LIBOR Loan. All other
accrued and unpaid interest hereunder shall be due and payable on December 31,
1995 and on the last day of each calendar quarter thereafter. A principal
payment in the amount of $433,333.00 shall be due and payable on September 30,
1996, and on the last day of each calendar quarter thereafter. All unpaid
principal and accrued and unpaid interest on this Note shall be due and payable
on January 26, 1997.

     Subject to the provisions of paragraphs (3) and (5) below, unless Borrower
has elected, pursuant to paragraph (2) below, that interest on all or a portion
of the outstanding principal amount of this Note shall accrue at the Adjusted
LIBOR Rate, Borrower shall


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pay interest on the outstanding principal amount of this Note at
the Base Rate.

          (1) Borrower may, at any time upon the expiration of any Interest
     Period, or at any time with respect to a portion of the outstanding
     principal balance of this Note that does not constitute a LIBOR Loan, elect
     that the per annum rate of interest on all or any portion of the
     outstanding principal amount of this Note accrue at the Base Rate. Accrued
     and unpaid interest on this Note under this paragraph (1) shall be
     calculated on the basis of a 365-day year, and the actual number of days
     elapsed.

          (2) Upon three (3) business days written notice to Lender of such
     election and of the Interest Period selected by Borrower, Borrower may,
     effective upon the expiration of any Interest Period, or effective any
     other time with respect to a portion of the outstanding principal balance
     of this Note that does not constitute a LIBOR Loan, elect that the per
     annum rate of interest on at least $100,000.00 of the outstanding principal
     amount of this Note accrue at the Adjusted LIBOR Rate, but only if at the
     time of such election (A) no Event of Default exists hereunder, and (B)
     after giving effect to such election, the aggregate number of all
     outstanding LIBOR Loans will not exceed eight (8). Accrued and unpaid
     interest on each LIBOR Loan shall be calculated on the basis of a 365-day
     year, and the actual number of days elapsed.

          (3) In the event that Lender shall have determined (which
     determination shall, absent manifest error, be final, conclusive and
     binding):

               (i) that adequate and fair means do not exist for ascertaining
          the applicable interest rate on the basis provided for in the
          definition of the LIBOR Rate;

               (ii) that the relevant LIBOR Rate does not represent the
          effective pricing to Lender for funding or maintaining a LIBOR Loan,
          or Lender shall incur increased costs or reductions in the amounts
          received or receivable hereunder in respect of any LIBOR Loan, in any
          such case because of (a) any change in any applicable law or
          governmental rule, regulation, guideline or order or any
          interpretation thereof and including the introduction of any new law
          or governmental rule, regulation, guideline or order (such as, for
          example but not limited to, a change in official

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     reserve requirements) and/or (b) other circumstances which materially and
     adversely affect Lender, the LIBOR Market, or the position of Lender in
     such market; or

          (iii) that the making or continuance by Lender of any LIBOR Loan has
     become unlawful by its compliance in good faith with any law, governmental
     rule, regulation, guideline or order (whether or not having the force of
     law and whether or not failure to comply therewith would be unlawful), or
     has become impracticable as a result of a contingency occurring which
     materially and adversely affects Lender, the LIBOR Market, or the position
     of Lender in such market;

then, and in any such event, Lender shall promptly after making such
determination give written notice to Borrower. Thereafter, in the case of clause
(i) or (ii) above, the applicable Adjusted LIBOR Rate shall be the per annum
rate of interest for each Interest Period specified from time to time by Lender,
taking into account the circumstances described above. Any subsequent election
of the Adjusted LIBOR Rate by Borrower shall be an election of the Adjusted
LIBOR Rate so specified by Lender. In the case of clause (iii) above, Borrower's
right to elect the Adjusted LIBOR Rate as the basis for determining accrued
interest under this Note shall be suspended until such time as Lender notifies
Borrower that the circumstances described in such clause no longer exist, and
interest on this Note shall, after the end of the then applicable Interest
Period(s), but subject to the post-default provisions of this Note, accrue
at the Base Rate.

     (4) Borrower shall compensate Lender, upon its written request (which
request shall set forth in reasonable detail the basis for requesting such
amounts and the calculation thereof and shall, absent manifest error, be final,
conclusive and binding), for all losses, expenses and liabilities (including,
without limitation, any loss, interest, expense, penalty or other amounts paid
or incurred by Lender in connection with any deposits or funds liquidated or
re-employed by Lender, to the extent not received by Lender in connection with
the re-employment of such funds) reasonably incurred by Lender (A) if any
repayment or-prepayment (including, without limitation, payment after
acceleration) of any LIBOR Loan occurs on a date which is not the last day of
the Interest Period applicable thereto, (B) if any prepayment of any LIBOR Loan
is not made on any date

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 specified in a notice of prepayment given by Borrower, or (C) as a consequence
 of any default by Borrower in repaying any interest or principal on this Note
 when required. The calculation of all amounts payable to Lender on LIBOR Loans
 shall be made on the assumption that Lender has funded each LIBOR Loan through
 the purchase of a Eurodollar deposit bearing interest at the Adjusted LIBOR
 Rate in an amount equal to the amount of such LIBOR Loan with a maturity
 equivalent to the Interest Period applicable to such LIBOR Loan, and through
 the transfer of such Eurodollar deposit from an office of Lender outside the
 United States to an office of Lender in the United States; provided that Lender
 may fund any LIBOR Loan in any manner that it chooses in its sole discretion
 and the foregoing assumptions shall only be made in order to calculate amounts
 payable under this Note.

     (5) In the event that Lender shall have determined that the adoption of any
requirement of law, rule or regulation regarding capital adequacy, or any change
therein or in the interpretation or application thereof, or compliance by
Lender with any request or directive regarding capital adequacy made or issued
(whether or not having the force of law and whether or not non-compliance
therewith would be unlawful) from any central bank or other governmental
authority or agency, does or will have the effect of increasing the amount of
capital required or expected to be maintained by Lender (or any corporation
controlling Lender), and Lender shall determine that such increase is based upon
the existence of Lender's commitment or obligations hereunder with respect to
making LIBOR Loans and other commitments or obligations of this type, then from
time to time upon the written demand by Lender to Borrower, Borrower shall pay
to Lender such additional amount or amounts as will compensate Lender for any
increased costs or reduced rate of return on capital or assets of Lender
resulting from such circumstances. A certificate as to any such additional
amount or amounts showing in reasonable detail the basis for the calculation
thereof submitted to Borrower by Lender shall, absent manifest error, be final,
conclusive and binding.

     (6) As used herein, the following terms shall have the following meanings:

          (i) "Adjusted LIBOR Rate" shall mean the LIBOR Rate plus one and
     one-fourth percent (1-1/4%) per annum.

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     (ii) "Base Rate" shall mean the variable rate of interest announced by
Lender from time to time as its base rate of interest and, without notice to
Borrower or any other person, such rate of interest shall change as and when
changes in that base rate of interest are announced. The Base Rate is set by
Lender as a general reference rate of interest, taking into account such factors
as Lender may deem appropriate, it being understood that many of Lender's
commercial or other loans are priced in relation to such rate, that it is not
necessarily the lowest or best rate of interest actually charged on any loan,
and that Lender may make various commercial or other loans at rates of interest
having no relationship to the Base Rate.

     (iii) "Interest Period" shall mean the interest period to be applicable to
any LIBOR Loan, each of which Interest Periods shall be either a one month
period, a two month period, a three month period or a six month period;
provided, however,

          (A) if any Interest Period would otherwise expire on a day which is
     not a business day, such Interest Period shall expire on the next
     succeeding business day; provided, that if any Interest Period would
     otherwise expire on a day which is not a business day but is a day of the
     month after which no further Business Day occurs in such month, such
     Interest Period shall expire on the immediately preceding business day;

          (B) if any Interest Period begins on a day for which there is no
     numerically corresponding day in the calendar month at the end of such
     Interest Period, such Interest Period shall end on the last business day of
     such calendar month; and

          (C) No Interest Period shall extend beyond the maturity date of this
     Note.

     (iv) "LIBOR Loan" shall mean at least $100,000.00 of the outstanding
principal balance of this Note as to which Borrower has elected the Adjusted
LIBOR Rate option.

     (v) "LIBOR Rate" shall mean, with respect to each Interest Period, but
subject to the provisions this Note, the rate per annum quoted by Lender

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               as the rate which Lender, in accordance with its usual practice,
               is offering first-class banks in the LIBOR Market for deposits of
               dollars (lawful money of the United States of America) for such
               Interest Period at or about 11:00 a.m. London, England time two
               (2) business days prior to the beginning of such Interest Period
               for delivery on the first day of such Interest Period.

                     (vi) "LIBOR Market" shall mean the London interbank
               Eurocurrency market.

         Upon the occurrence of an Event of Default (hereinafter defined), or
in the event this Note is declared due, interest shall accrue at the Maximum
Rate.

         The occurrence of any of the following shall constitute an "Event of
Default" under this Note:

              (a) Any default in the payment of any installment of interest when
         due hereunder if such default remains uncured for a period of three (3)
         days after Lender gives written notice of the existence thereof to
         Borrower;

              (b) Any default in the payment of any installment of principal
         when due hereunder, or any other default hereunder;

              (c) Any Event of Default under, and as defined in, that certain
         Loan Agreement dated August 20, 1993, by and between Lender and KSA
         Industries, Inc. ("KSA") , as amended by that certain First Amendment
         to Loan Agreement dated September 8, 1993 between KSA and Lender, by
         that certain Second Amendment to Loan Agreement dated May 31, 1994
         between KSA and Lender and by that certain Third Amendment to Loan
         Agreement dated April 28, 1995 between KSA and Lender, and as the same
         may be further amended from time to time;

              (d) Any Event of Default under, and as defined in, that certain
         Loan Agreement dated October 27, 1993 by and among Lender and Service
         Transport Company, Borrower, Ada Crude Oil Company, Buckley Mining
         Corporation, Ada Resources, Inc., CJC Leasing, Inc., Classic Coal
         Corporation, Ada Mining Corporation and Bayou City Barge Lines, Inc.
         (collectively, the "Borrower Group"), as amended by that certain First
         Amendment to Loan Agreement dated October 27, 1994 among the Borrower
         Group and Lender and by that certain Second Amendment to Loan Agreement
         of even date herewith among the Borrower Group


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         and Lender, and as the same may be further amended from time to time;
         or

              (e) Any Event of Default under, and as defined in, that certain
         Note Purchase Agreement (the "Note Purchase Agreement") of even date
         herewith, executed by KSA for the benefit of Lender.

         Upon the occurrence of an Event of Default hereunder, Lender may
accelerate and declare this Note immediately due and payable without notice. Any
failure to exercise this option shall not constitute a waiver by Lender of the
right to exercise the same at any other time. It is agreed that time is of the
essence of this agreement.

         Borrower may prepay this Note, in whole or in part, at any time prior
to maturity without penalty (except as may be expressly required pursuant to the
provisions of this Note), and interest shall cease on any amount prepaid. Any
partial prepayment shall be applied to payments in the inverse order of
maturity.

         Any check, draft, money order or other instrument given in payment of
all or any part hereof may be accepted by the holder hereof and handled in
collection in a customary manner, but same shall not constitute payment hereof
or diminish any rights of Lender except to the extent that actual cash proceeds
of such instrument are unconditionally received by Lender.

         Borrower hereby agrees to pay all expenses, including reasonable
attorneys' fees, all of which shall become a part of the principal hereof,
incurred by Lender if this Note is placed in the hands of an attorney for
collection or if collected by suit or through any probate, bankruptcy or any
other legal proceedings.

         It is expressly stipulated and agreed to be the intent of Borrower and
Lender to comply with applicable Texas law governing the maximum non-usurious
rate or amount of interest payable on or in connection with this Note (or
applicable United States federal law to the extent that it permits Lender to
contract for, charge, take, reserve or receive a greater amount of interest than
under Texas law). Accordingly, it is agreed that notwithstanding any provision
to the contrary in this Note, or in any of the documents securing payment hereof
or otherwise relating hereto, no such provision shall require the payment or
permit the collection of interest in excess of the Maximum Rate. If any excess
of interest in such respect is provided for, or shall be judicially interpreted
to be so provided for, in this Note or in any of the documents securing payment
hereof or otherwise relating hereto, or if the acceleration of the maturity of
this Note or any prepayment by Borrower results in Borrower's having paid any
interest in excess of that permitted by applicable law, then in any such event,
it is


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the express intent of Borrower and Lender that (1) the provisions of this
paragraph shall govern and control, (2) neither Borrower nor any endorser or
guarantor of this Note, nor their respective heirs, legal representatives,
successors or assigns, nor any other party liable for the payment hereof, shall
be obligated to pay the amount of such interest to the extent that it is in
excess of the Maximum Rate, (3) any such excess which may have been collected
shall be either applied as a credit against the then unpaid principal amount
hereof or refunded to Borrower, and (4) the provisions of this Note and any
documents securing payment of this Note shall be automatically deemed reformed
and the amounts thereafter collectible thereunder reduced, without the necessity
of the execution of any new document, so that the effective rate of interest
shall be reduced to the Maximum Rate. For the purpose of determining the Maximum
Rate, all sums paid or agreed to be paid to Lender for the use, forbearance or
detention of the proceeds of this Note shall be amortized, prorated, allocated
and spread throughout the full term of this Note so that the rate or amount of
interest on account of this Note is uniform throughout the term hereof and does
not exceed the applicable usury ceiling.

         Borrower agrees that the Maximum Rate to be charged or collected
pursuant to this Note shall be the applicable indicated rate ceiling as defined
in TEX. REV. CIV. STAT. ANN. Art. 5069-1.04, provided that Lender may rely on
other applicable laws, including without limitation laws of the United States,
for calculation of the Maximum Rate if the application thereof results in a
greater Maximum Rate. Except as provided above, the provisions of this Note
shall be governed by the laws of the State of Texas.

         Each maker, surety, guarantor and endorser waives demand, grace,
notice, presentment for payment, notice of intention to accelerate the maturity
hereof, notice of the acceleration of the maturity hereof and protest, and
agrees that this Note and the liens securing its payment may be renewed, and the
time of payment extended, from time to time, without notice and without
releasing any of the foregoing.

         This Note is given in renewal and extension of a Promissory Note dated
June 15, 1995, executed by Borrower, payable to the order of Lender in the
amount of $5,200,000.00, which Promissory Note was given in renewal and
extension of a Promissory Note (the "Original Note") dated April 13, 1994,
executed by Borrower, payable to Lender in the amount of $5,200,000.00, and the
liens securing the payment thereof are not released but are hereby ratified and
hereby carried forward to secure this Note.

         The principal of the Original Note was advanced by Lender to Borrower
to permit Borrower to acquire certain oil and gas properties from Torch-I
Development Drilling Program, Ltd. Borrower will not sell, transfer, pledge,
encumber or otherwise


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<PAGE>   9
dispose of any of such oil and gas properties without the prior written consent
of Lender.

         This Note is the Note referred to in, is subject to, and is entitled to
the benefits of, the Note Purchase Agreement and that certain Guaranty Agreement
dated October 27, 1993, executed by Adams Resources & Energy, Inc. for the
benefit of Lender, as amended from time to time, including by that certain
Amendment to Guaranty Agreement of even date herewith, executed by Adams
Resources & Energy, Inc. for the benefit of Lender.

         Borrower represents and warrants that this loan is for business,
commercial, investment or similar purpose and not primarily for personal, family
or household use, as such terms are used in (i) Chapter One of the Texas Credit
Code, (ii) 12 CFR 226 (1969 and as amended) and (iii) 12 CFR Part 34, Subpart B
(1988).

                                     ADAMS RESOURCES EXPLORATION
                                     CORPORATION


                                     By:
                                        ----------------------------------------
                                        Name:
                                             -----------------------------------
                                        Title:          Treasurer
                                              ----------------------------------

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<PAGE>   10
                            NOTE PURCHASE AGREEMENT


         THIS NOTE PURCHASE AGREEMENT (this "Note Purchase Agreement") dated the
29th day of December, 1995, is among KSA INDUSTRIES, INC., a Delaware
corporation (the "Purchaser") , ADAMS RESOURCES EXPLORATION CORPORATION, a
Delaware corporation (the "Borrower"), and NATIONSBANK OF TEXAS, N.A., a
national banking association (the "Bank")

         1. Declaration. The Borrower has executed a promissory note dated of
even date herewith, in the original principal amount of $5,200,000.00, payable
to the order of the Bank (which promissory note or any renewal, extension or
rearrangement thereof is referred to herein as the "Note"), a copy of which is
attached hereto as Exhibit "A". As a condition precedent to funding the Note,
the Bank requires the Purchaser to enter into this Note Purchase Agreement. The
Purchaser believes, and represents and warrants to the Bank, that the Purchaser
will obtain substantial benefit from the loan made by the Bank to the Borrower
pursuant to the Note. Therefore, in order to induce the Bank to fund the Note
and enter into all related credit documents, and for other good and valuable
considerations, the receipt and sufficiency of which are hereby acknowledged,
the Borrower, the Purchaser and the Bank hereby agree to the terms set forth
herein.

         2. Events of Default. For purposes of this Note Purchase Agreement,
each of the following items will be an event of default ("Event of Default")
hereunder:

            2.01 The Borrower shall fail to pay all amounts due under the Note
on or prior to the date on which the Note matures, whether upon acceleration, or
at any other time;

            2.02 Any other default, however denominated, under the terms of this
Note Purchase Agreement, the Note or any agreement securing the Note or any
related credit document, shall have occurred;

            2.03 Any representation or warranty made in this Note Purchase
Agreement, the Note or any related credit document shall prove to be incorrect
in any material respect when made;

            2.04 Any Event of Default under, and as defined in, that certain
Loan Agreement dated August 20, 1993, between the Purchaser and the Bank, as
amended by that certain First Amendment to Loan Agreement dated September 8,
1993 between the Purchaser and the Bank, by that certain Second Amendment to
Loan Agreement dated May 31, 1994 between the Purchaser and the Bank and by that
certain Third Amendment to Loan Agreement dated April 28, 1995 between the
Purchaser and the Bank, and as the same may be further amended from time to
time, shall have occurred, or if the commitment of the Bank under said Loan
Agreement is terminated for any reason; or
<PAGE>   11
            2.05 Any Event of Default under, and as defined in, that certain
Loan Agreement dated October 27, 1993, among the Bank and Service Transport
Company, the Borrower, Ada Crude Oil Company, Buckley Mining Corporation, Ada
Resources, Inc., CJC Leasing, Inc., Classic Coal Corporation, Ada Mining
Corporation and Bayou City Barge Lines, Inc. (collectively, the "Borrower
Group") , as amended by that certain First Amendment to Loan Agreement dated
October 27, 1994 among the Borrower Group and the Bank and by that certain
Second Amendment to Loan Agreement of even date herewith among the Borrower
Group and the Bank, and as the same may be further amended from time to time,
shall have occurred.

         3. Note Purchase.

            3.01 Note Purchase Obligation. Following an Event of Default, the
Bank may at any time request that Purchaser purchase the Note, and, within five
(5) business days after such request is made, Purchaser will purchase the Note
by paying to the Bank, as the purchase price therefor, an amount (the "Purchase
Amount") equal to the entire outstanding principal balance of and accrued and
unpaid interest on the Note and all other fees or indebtedness owed to the Bank
under the Note, any document securing the Note or any related credit document as
of the date of such purchase, such payment to be made at Bank's office at 700
Louisiana, 8th Floor, Houston, Texas 77002, in lawful money of the United States
and in immediately available funds, without offset, defense or counterclaim.

            3.02 Assignment and Delegation. If the Note is purchased by
Purchaser pursuant to this Note Purchase Agreement, the Bank upon receipt of the
Purchase Amount, shall endorse and deliver the Note to Purchaser and assign and
delegate all of the Bank's rights and duties under the Note, all without
recourse to the Bank and without representations or warranties of any kind or
character, express or implied, except for the Bank's warranty of title to the
Note. Purchaser agrees to accept the assignment and delegation and therefore to
accept the rights and assume the duties of the Bank in relation thereto. The
Borrower agrees, that following such assignment and delegation, the Bank shall
be released from any duties the Bank might have to the Borrower under the Note
or any related documents, and that following such assignment and delegation, the
Borrower will look solely to the Purchaser for performance of those duties. The
Borrower agrees that following such assignment and delegation, the Borrower will
remain fully bound by the terms and conditions of the Note and any related
documents as if the Purchaser had been the Bank when the Note and any other
documents were initially executed.

            3.03 Subordination. If the Note is purchased by the Purchaser
pursuant to this Note Purchase Agreement, the Purchaser may receive payments on
the Note unless and until such time as


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<PAGE>   12
Borrower is in default of any of its obligations to the Bank, or any document or
instrument on which the Borrower has liability is in default to the Bank, after
which time the Purchaser will not ask, demand, sue for, take or receive any part
of the indebtedness evidenced by the Note unless or until all indebtedness of
the Borrower to the Bank, now existing or hereafter arising, shall have been
paid in full. Notwithstanding the foregoing, at all times after its purchase of
the Note pursuant to this Note Purchase Agreement, the Purchaser shall be
entitled to receive, and shall apply against the indebtedness evidenced by the
Note, all proceeds generated by the operation or sale of the oil and gas
properties acquired by the Borrower with the proceeds of the Note. The Purchaser
hereby agrees that, except as expressly set forth above, in the event it
purchases the Note from the Bank, all of its rights to receive any payments
under the Note from the Borrower, as well as any and all rights it may have or
acquire to any security for the repayment of the Note other than the proceeds of
the oil and gas properties described above, shall be subordinate and junior in
all respects to all indebtedness of the Borrower to the Bank outstanding at any
time, whether now or hereafter incurred, created or evidenced, and however such
indebtedness may be extended, renewed or evidenced, as well as to all security
held by the Bank for such indebtedness.

         4. Purchaser's Representations and Warranties. The Purchaser hereby
represents and warrants to the Bank as follows:

            4.01 Documents. The Purchaser (i) has examined the Note and the
related credit documents and approved them for the purposes of this Note
Purchase Agreement and (ii) agrees to any renewal, extension or rearrangement of
the Note or any related credit document which may hereafter be executed in
connection with the Note.

            4.02 Authority. The Purchaser is a corporation duly organized,
validly existing and in good standing under the laws of the State of Delaware.
The execution, delivery and performance by the Purchaser of this Note Purchase
Agreement are within the Purchaser's powers, have been duly authorized by all
necessary action, will not contravene (i) the Purchaser's Certificate of
Incorporation or Bylaws or (ii) any law, regulation, order or material
contractual restriction affecting the Purchaser or its property and will not
result in, or require the creation or imposition of, any lien on any of the
Purchaser's property, assets or revenues pursuant to the provisions of any such
contract or other agreement, instrument or undertaking. No authorization or
approval or other action by, and no notice to or filing with, any governmental
authority or regulatory body is required for the due execution, delivery and
performance by the Purchaser of this Note Purchase Agreement.


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<PAGE>   13
            4.03 Binding Obligations. This Note Purchase Agreement is the legal,
valid and binding obligation of the Purchaser, enforceable against the Purchaser
in accordance with its terms, subject to the effect of any applicable
bankruptcy, insolvency, reorganization, moratorium or similar law affecting
creditors' rights generally.

         5. Purchaser's Covenants.

            5.01 Purchase Obligation Absolute. The Purchaser will perform under
the terms of this Note Purchase Agreement regardless of any law, regulation or
order now or hereafter in effect in any jurisdiction affecting any of such terms
or the rights of the Bank with respect thereto. The duty of the Purchaser
hereunder shall be absolute and unconditional irrespective of:

                 (a) any default or event of default, however, denominated, that
         has occurred under the Note or any related credit document;

                 (b) any lack of validity or enforceability of the Note or any
         related credit document;

                 (c) any amendment to, waiver of or consent to departure from
         the terms of the Note or any related credit document;

                 (d) any renewal, extension, assumption or rearrangement of, or
         any other indulgence with respect to, the Note or any related credit
         document;

                 (e) any exchange, release or non-perfection of any collateral,
         or any release of, amendment to, waiver of or consent to departure from
         any guaranty hereafter executed in favor of the Bank guaranteeing the
         obligations of Borrower under the Note or any related credit document;

                 (f) any lack of validity or enforceability of any lien on any
         collateral securing the repayment of the Note or any related credit
         document, including a lack of validity or enforceability due to prior
         or otherwise competing liens;

                 (g) any lack of creditworthiness of the Borrower, including the
         Borrower's bankruptcy, assignment for the benefit of creditors or
         appointment of a receiver; or

                 (h) any other circumstances which might otherwise constitute a
         defense available to, or a discharge of, the Borrower or any guarantor.

            5.02 Payment Amount. The Purchaser agrees that, to the extent that
the Borrower makes payments to the Bank, or the Bank


                                      -4-
<PAGE>   14
receives any proceeds of collateral, and such payments or proceeds or any part
thereof are subsequently invalidated, declared to be fraudulent or preferential,
set aside or otherwise required to be repaid, then to the extent the Purchase
Amount would have been reduced by the amount of such invalidated, set aside or
repaid payments, the Purchase Amount shall be increased to reflect such
occurrence. The Purchaser shall defend and indemnify the Bank from and against
any claim or loss under this Section (including reasonable attorneys, fees and
expenses) in the defense of any such action or suit.

            5.03 Waiver of Notices. The Purchaser hereby waives promptness,
diligence, notice of acceptance, notice of acceleration, notice of intent to
accelerate and any other notice with respect to any actions the Bank may take
pursuant to this Note Purchase Agreement, the Note or any related credit
document. Nothing in this Section is intended to eliminate the requirement that
the Bank make a request to purchase the Note pursuant to Section 3.01 of this
Note Purchase Agreement.

            5.04 Other Remedies. The Purchaser hereby waives any requirement
that the Bank protect, secure, perfect or insure any lien or any property
subject thereto or exhaust any right or take any action against the Borrower or
any other person or any collateral, including any action required by Chapter 34
of the Texas Business and Commerce Code.

            5.05 Costs and Expenses. The Purchaser agrees to pay to the Bank all
costs, attorneys' fees and other expenses incurred by the Bank in an effort to
enforce and/or collect all or any part of the indebtedness evidenced by the
Note, or to enforce any of the Purchaser's obligations hereunder.

         6. Remedies.

            6.01 Right of Set-Off. Upon making the request that the Purchaser
purchase the Note pursuant to Section 3.01 hereof, the Bank is authorized to
hold as collateral for the payment of the Purchase Amount any funds, investment
accounts or deposits the Purchaser has at the Bank, up to the amount of the
Purchase Amount, and, if the Purchaser defaults in the payment of the Purchase
Amount when due, to set off and apply any funds, investment accounts or deposits
and other indebtedness that the Bank owes the Purchaser against any and all of
the obligations of the Purchaser under this Note Purchase Agreement. The Bank
agrees promptly to notify the Purchaser after any such holding of collateral or
set-off made by the Bank, provided that the failure to give such notice shall
not affect the validity of such holding of collateral or set-off.


                                      -5-
<PAGE>   15
            6.02 Limitation of Remedy. If the Bank should breach any of the
terms of this Note Purchase Agreement, the Bank shall be liable for actual
damages, if any, incurred by the Purchaser as a result of such breach, but such
breach shall in no way release the Purchaser from its obligations hereunder,
including the Purchaser's obligation to purchase the Note for the Purchase
Amount, and any damages the Purchaser might incur as a result of such breach
shall not be offset against the Purchase Amount that the Purchaser is required
to pay under the terms of this Note Purchase Agreement.

         7. Miscellaneous.

            7.01 Notice. Unless otherwise specified, all notices and other
communications provided for in this Note Purchase Agreement shall be in writing
and delivered or transmitted, including by telecopy, to the addresses set forth
below the signatures herein, or to such other address as shall be designated by
the Purchaser, the Borrower or the Bank in written notice to the other parties.
Any notice pursuant to this Note Purchase Agreement shall be deemed given when
received by the party to whom it is directed or when deposited in the United
States mail, certified, return receipt requested, with the postage prepaid,
addressed to the party as provided herein.

            7.02 Amendments, Etc. No amendment or waiver of any provision of
this Note Purchase Agreement, nor any consent to any departure by the Purchaser
or the Borrower therefrom, shall be effective unless the same shall be in
writing and signed by the Bank, and then such waiver or consent shall be
effective only in the specific instance and for the specific purpose for which
given.

            7.03 No Waiver. No failure on the part of the Bank to exercise, and
no delay in exercising, any right hereunder shall operate as a waiver thereof;
nor shall any single or partial exercise of any right hereunder preclude any
other or further exercise thereof or the exercise of any other right.

            7.04 Transfer of Interest. This Note Purchase Agreement shall create
a continuing obligation and shall (a) remain in full force and effect until
payment in full and termination of the obligations of Borrower to the Bank under
the Note and all related credit documents, (b) be binding upon the Borrower, the
Purchaser and their respective heirs, legal representatives, successors and
assigns, and (c) inure, together with the rights and remedies of the Bank
hereunder, to the benefit of the Bank and its successors, transferees and
assigns. The Purchaser may not assign its rights nor delegate its duties
hereunder without the prior written permission of the Bank.

            7.05 Termination of Purchase Obligation. When the Borrower has fully
paid or otherwise performed the obligations under the Note and all related
credit documents, and the Bank has


                                      -6-
<PAGE>   16
received all of the outstanding principal, interest, fees and other amounts due
it under the Note and all related credit documents, the obligations of the
Purchaser hereunder shall be terminated and released.

            7.06 Governing Law. THIS NOTE PURCHASE AGREEMENT SHALL BE GOVERNED
BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF TEXAS.

            7.07 Counterparts. This Note Purchase Agreement may be executed in
multiple counterparts, any one or more of which may contain the signature of
any party hereto. All of such counterparts taken together shall constitute a
complete executed original hereof.

            EXECUTED as of the day and year first above written.


                                     KSA INDUSTRIES, INC.                
                                                                        
                                                                         
                                                                         
                                     By: /s/   Scott L. Thompson           
                                        ---------------------------------
                                        Name:  Scott L. Thompson
                                             ----------------------------
                                        Title: EVP
                                              ---------------------------  
                                                                         
                                     Address for Notice:                 
                                     6910 Fannin                         
                                     Houston, Texas 77030                
                                     Telecopy No.: 797-9301              
                                                                         
                                                                         
                                     ADAMS RESOURCES EXPLORATION         
                                     CORPORATION                         


                                     By:                                 
                                        ---------------------------------
                                        Name:
                                             ----------------------------
                                        Title:  Treasurer
                                              ---------------------------      
                                                                         
                                     Address for Notice:                 
                                     6910 Fannin                         
                                     Houston, Texas 77030                
                                     Telecopy No.: 795-4495              


                                       -7-
                                                                         
                                     
<PAGE>   17
                                     NATIONSBANK OF TEXAS, N.A.   
                                                                 
                                                                 
                                                
                                     By:       /s/ James R. Allred          
                                        ---------------------------------
                                        Name:  James R. Allred          
                                             ----------------------------
                                        Title: Vice President
                                              ---------------------------      

                                                                 
                                     Address for Notice:         
                                     700 Louisiana, 8th Floor    
                                     Houston, Texas 77002        
                                     Telecopy No.: 247-6432      

                                      -8-