<PAGE>
                                                                   EXHIBIT 10.43

                           CONTRACT FOR THE SUPPLY OF
                        CRUDE OIL FROM THE PARISIAN BASIN


BETWEEN:

ELF ANTAR FRANCE, having a share capital of 1,422,2 15,000 francs, registered
office Tour Elf, 2 place de la Coupole, La Defense 6,924OO COURBEVOIE, Nanterre
company number B 302 556 832 (hereinafter referred to as " the Purchaser"),
represented by Robert DUCHESNE, , acting in his capacity of Procurement and
Marketing Manager and duly authorised for the purposes hereof of the fast part
AND MIDLAND MADISON PETROLEUM COMPANY, general partnership with a share capital
of 1,000,OOO francs, registered office 16 Place Vendome, 75001 PARIS, Paris
company number B 391727 450 (hereinafter referred to as "the Vendor",
represented by Erik DALBIEZ , acting in his capacity of Manager and duly
authorised for the purposes hereof of the second part hereinafter collectively
referred to as 'the parties"

IT HAS BEEN AGREED AS FOLLOWS:

                                   DEFINITIONS

The parties agree that in this contract ("the contract") the terms hereinbelow
shall have the following meanings:

- REPRESENTATIVE SAMPLE OF DAILY DELIVERIES:

     A sample taken by mixing and homogenizing samples from the Grandpuits
     refinery in trucks delivering between 0 and 2400H each day crude deriving
     from the same concession.

- REPRESENTATIVE SAMPLE OF MONTHLY DELIVERIES:

     For pipeline deliveries, sampling done by an on-line automatic sampler
     associated with the outlet for crude conveyed by pipeline between OH of the
     first day of a given month and 2400H of the last day of the said month.

     For deliveries by truck, a sample taken by mixing and homogenizing samples
     from trucks from the same concession between OH of the first day of a given
     month and 2400 H of the last day of the said month.

- DELIVERY FOR MONTH M:

     This corresponds to the volume of crude free of water and sediment
     expressed in barrels at 60" F (the barrel by M3 factor used shall be equal
     to 6.29) and delivered to Grandpuits between OH of the fast day of a given
     month and 2400H of the last day of the said month.

BATCH DELIVERED:

     Each batch delivered by pipeline corresponds to the sum of the consignments
     made daily from to 2400H between OH Monday and 2400H Sunday.

     At the beginning of the month, the batch delivered by pipeline shall
     consist of daily consi between OH00 on the first day of the month and 24HOO
     of the first Sunday. At the end month the batch delivered by pipeline shall
     consist of daily despatches between OH00 on Monday of the month and 24HOO
     of the last day of the month.


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<PAGE>


- CLOSURE OF THE GRANDPUITS REFINERY:

     For the purposes hereof the date of closure of the refinery shall be the
     date of expiration of the period of one month following notification of the
     Administration by the Purchaser of the decision to close pursuant to the
     Oil Industry Law of 92-1443 of December 31, 1992.

     In the event that the declaration of closure is made to the authorities
     after shipments are halted, the date of closure shall be deemed to be the
     date of receipt at the Le Havre oil terminus of the last tonne of oil
     imported for processing in the Grandpuits refinery.

- CONCESSION: in this contract, the term "Concession " applies to all the
     following:

    - Exploration licence,

    - Exploitation concession,

1. PURPOSE OF CONTRACT

The Vendor agrees to sell the Producer and deliver to the Purchaser, and the
Purchaser agrees to buy from the Vendor, in accordance with the methods and
conditions set out herein, the portion of crude oil production extracted from
the concessions held by the Vendor as set out hereinafter :

                     CHAMPROSE (100%) and CHARMOTTES (100%)

The Vendor may additionally make an offer to the Purchaser by certified letter
with acknowledgment of receipt to buy from it all that part of the production it
is entitled to as new exploration in the Parisian basin for the term of the
contract under the same conditions as those herein for a crude of equivalent
quality. The Purchaser shall have a period of one month from receipt of the
Vendor's request to notify the Vendor by certified letter with acknowledgment of
receipt of its acceptance or rejection of the offer. Should the Purchaser
approve, the Contract shall be given a rider.

The Vendor may also make an offer to the Purchaser by certified letter with
acknowledgment of receipt to buy from it all its production sourced from the
Vendor's acquisition of already existing production in the Paris basin, for the
term of the contract under the same conditions as those herein for a crude of
equivalent quality. The Purchaser shall have a period of one month from receipt
of the Vendor's request to notify the Vendor by certified letter with
acknowledgment of receipt of its acceptance or rejection of the offer. Should
the Purchaser approve, the Contract shall be given a rider.

In the event that the production of crude oil the subject-matter of this
Contract, such as production of crude oil from new operations, should be shared
between several producers, only those portions of the production belonging to
the Vendor shall benefit from the terms hereof. In consequence thereof, the
Vendor agrees to inform the Purchaser by certified letter with acknowledgment of
receipt within one month of any changes of associates and any change in the
amount of its share in the concession.

In any event the Purchaser shall not be obliged to accept under the terms of
this contract a quantity of crude oil greater than 100,000 metric tonnes per
annum.

2. PRICE

The price P (in French Francs per US barrel of crude oil free of sediment and
water delivered in the Grandpuits refinery crude vats) shall be obtained by
applying the following formula:

                                   P=(A+B+C)xD

A is equal in value to the arithmetic mean of all average daily quotations (spot
assessment) of the Dated Brent published in Platt's Oil Market Wire during month
M + 1 for the month M deliveries



                                       2
<PAGE>



The value of B is equal to : -1.50 USD/bbl (minus one dollar and sixty cents per
barrel).

The value of C is equal to 0 for pipeline deliveries and -0.30 USD/bbl (minus
thirty cents perfor truck deliveries.

D is equal in value to the arithmetic mean of all average daily quotations for
the exchange rate French francs of the US dollar, as indicated by the Banque de
France and subsequently published French Republic Official Gazette during month
M+ 1 (for the month M deliveries).

Items A,B,C,D, and P shall be rounded up to two decimal places.

3. DUTIES AND TAXES

All duties, taxes, income tax, royalties or other charges on the contract crude
oil shall be borne by the Vendor.

4. INVOICING AND PAYMENT

The Vendor shall make out its invoices on the basis of net quantities received
at refinery by the Purchaser during a given month.

Payment for supply of crude oil under the Contract shall be made in French
francs in France by bank transfer.

Payment shall be made within six working days of the date of issue of the
invoice, which the Vendor agrees to send to the Purchaser by fax and post the
same day.

5. DETERMINATION OF QUANTITIES DELIVERED

The monthly quantities of crude oil free of water and sediment to be taken into
account for invoicing shall be determined :

     - For truck deliveries to the Grandpuits refinery on the basis of
     representative samples of the monthly deliveries corresponding to each
     Concession and quantities measured by weighing on the weighbridges at the
     Grandpuits refinery.

The weighbridges are approved MIS and calibrated twice a year, once in the
presence of the DRIIE

     - For pipeline deliveries to the Grandpuits refinery on the basis of
     analyses of the representative sample from each batch delivered in the
     month or in default thereof the representative sample from monthly
     deliveries corresponding to each Concession and quantities measured by an
     approved MIS counting system and transmitted by the operator of the
     Purchaser's pipeline.

The counting device is calibrated twice a year, once in the presence of the
DRIRE.

If the difference between 2 calibrations is greater than 0.2% the frequency of
calibration may by consent of both parties be increased to 3 months.

In the event of an anomaly detected by the Purchaser or the Vendor the
measurement of the quantities delivered by pipeline shall be made by both
parties on the basis of quantities measured by dipping in the transport vats.


                                       3

<PAGE>


An estimate of the quantity delivered in month M shall be provided to the
Purchaser by the Vendor on the 15" of month M-l.

6. QUALITY

Analyses shall be carried out in accordance with the following methods :

Density:                        ASTM D5002
Water content:                        ASTM D4006
Sediment content:               ASTM D473
Salt content:                         ASTM D3230
REID Vapour Pressure:           ASTM D323
Pour point:                           ASTM D97

Crude oil deliveries should satisfy the following specifications:

- Water content less than 0.5%

- REID Vapour Pressure at 37.8 C less than 0.8 bar

- Chloride content less than 100 mg of NaCl/l

- Pour point < 6 C for pipeline transport.- the crude shall be of the quality
usually produced on the Concession and shall be known to be of commercial
quality.

- the crude oil shall not have undergone other operations than pouring,
dehydration and de-salting.

- Any addition of chemical products by the Vendor to the crude oil must have the
prior written approval of the Purchaser before use.

All trucks are to be checked by the Purchaser when being drained before
emptying.

Should water be present when draining the trunk the tank is drained before being
emptied or rejected by the Purchaser.

7. MONITORING CRUDE OIL QUALITY

For pipeline reception the monitoring of crude oil quality shall be carried out
by an independent laboratory approved by the parties, according to the methods
outlined in clause 6, upon the representative sample from each batch delivered
in the month or in default thereof upon the representative sample from monthly
deliveries, obtained by an automatic sampler at the start of the pipeline.

Each representative sample shall be divided into four samples each stored in a
sterile bottle and distributed as follows :

- 1 for the Purchaser

- 1 for the Vendor

- 1 for the independent laboratory

- 1 in reserve.

Each sample shall be sealed, labeled, and kept for a period of two months. In
the event that analysis results are disputed by either party the reserve sample
shall be analysed by a neutral laboratory, chosen by agreement of the parties.
The said laboratory's conclusions shall be binding on the parties.

Expenses arising from analyses of samples from pipeline deliveries shall be
borne by the Vendor.


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<PAGE>
For truck reception the monitoring of the crude oil quality shall be by
analysis, using the methods outlined in clause 6, of the representative sample
from daily deliveries made by the refinery in accordance with the following
sampling rule:


<Table>
<Caption>
    Monthly Reception per         Average Number of Trucks per
          Concession                          Day                    Number of Daily Samples
    ---------------------         ----------------------------       -----------------------
<S>                               <C>                                <C>
            <1500                              <3                               1
          1500-4000                          3 to 6                             2
          4000-10000                        8 to 20                             3
  for each additional 10,000                  +20                              +1
</Table>


The refinery shall keep the representative samples from monthly deliveries for
each Concession for a period of two months.

Analyses of samples from truck deliveries shall be at the Vendor's expense.

In the event that analysis results are disputed, the Vendor must notify the
Purchaser by the 15th of the month following the month of reception of the crude
oil at the latest. The said sample shall be analysed by a neutral laboratory,
chosen by agreement of the parties. The said laboratory's conclusions shall be
binding on the parties.

For both truck and pipeline reception: in the event that the first laboratory's
cost of analyses made by the second laboratory shall be borne by the party
making an objection or the Vendor if the crude is found not to be of the
required quality.

8. PRODUCTION CHARGES AND DATA TRANSFER.

With respect to Concessions operated by several producers or the transporting of
crude oil for a third party, production charges payable respectively to the
Vendor and other producers shall be calculated by application of the rules
hereinbelow.

For delivery on behalf of producers operating the same Concession, the quantity
of crude due to each producer is calculated monthly for each Concession by
multiplying the producer's share in the Concession by the total quantity of
crude free of water and sediment delivered over the month.

The quantities of crude free of water and sediment accepted for invoicing are
those calculated by the Grandpuits refinery for lorry deliveries and by the
pipeline operator for pipeline deliveries.

With respect to pipeline deliveries the monthly summary of "Gross" volumes and
net quantities sold by each producer of crude conveyed by pipeline shall be sent
by the pipeline operator to the Purchaser on the second working day of the month
following the month of delivery at the latest.

9. TRANSPORTING CRUDE AND TRANSFER OF OWNERSHIP

Transport shall be organised by the Vendor at its own-risk and expense in
compliance with the refinery's rules for the reception of crude (particularly
opening hours for "shipments" at the refinery).

The Vendor shall deliver and the Purchaser shall buy the contract quantities
brought to the entrance of the Grandpuits Refinery's storage facilities.



                                       5
<PAGE>



The Purchaser shall become owner of the quantities delivered at the refinery and
all risks pertaining thereto shall be are to be borne by the operator by it when
the crude oil passes the connecting flange of the storage facilities at the
refinery.

10. ASSIGNMENT OF CONTRACT

Neither the Purchaser nor the Vendor may assign all or part of their rights or
obligations under the Contract to any other company without having first
obtained the written consent of the other party.

However, no prior approval of the Vendor or the Purchaser shall be necessary in
the event of assignment to one of the affiliated companies of either party.

"Affiliated Company" means any company in which either party holds directly or
indirectly more than 50% of the capital.

In the event of assignment, the Purchaser and/or the Vendor shall remain jointly
liable to the other party for full performance of the Contract by the assignee
company.

11. TERM OF CONTRACT

This contract shall take effect on 01/01/97.

It is agreed to have a term of three years.

It may then be renewed automatically for periods of one year unless notice is
given by certified letter with acknowledgment of receipt by either of the
parties at least six months before the due date.

12. STORAGE AND TRANSPORT BY PLIF

In the event of repudiation of the contract by the Purchaser the Vendor agrees
to transport the crude oil produced by the Vendor between Grandpuits and
Gargenville via the PLIF (Ile de France Pipeline). The said agreement shall
result in signature by both parties of a transport contract with a term of 96
months, within six months of repudiation of the Contract.

The services provided for in the said transport contract shall include:

- storage and handling at Grandpuits

- transport via PLIF in regular batches not less than 20,000 m3 in size

- storage and handling at Gargenville.

They shall be invoiced at rates comparable to those practised in the petroleum
profession for identical services, taking into account the costs relating to
logistic constraints upon the Purchaser, especially but not exhaustively:

- operations preliminary to placing the crude on line.

- Working over the pipeline.


                                       6
<PAGE>


It is hereby agreed that:

    - during the first period of 48 months the Purchaser may not repudiate the
    transport contract save for force majeure. During the second period of 48
    months the Purchaser may repudiate the transport contract at 6 months'
    notice.,

    - however, in the event of closure of the GRANDPUITS refinery, the Purchaser
    may repudiate the transport contract at 2 years' notice during the first
    period of 48 months and at 6 months' notice during the second period of 48
    months.


13. EQUITY CLAUSE

If during the term of the Contract one of the parties considers itself no longer
able to continue performance of the same, solely for reasons beyond its control
having the effect of causing it to suffer costs that should not in conscience be
imposed upon it, the party concerned shall notify the other by certitied letter
with acknowledgment of receipt, and both parties shall confer for the purpose of
adopting appropriate measures in the circumstances in their mutual interest.

If after two months from the date of receipt of the abovementioned letter, the
Parties fail to agree on the steps to be taken, the Contract may lawfully be
repudiated with no compensation payable at either party's demand at one month's
notice by certified letter with acknowledgment of receipt.

14. PRIOR CONTRACTS

This contract renders null and void and replaces any contract previously made
between the parties for the sale and transport of the crude which is the
subject-matter of the Contract.

15. GOVERNING LAW

French shall be the language of the contract.

The laws of France shall be applied to the interpretation and application of the
terms of the Contract.

16. JURISDICTION

In the event of dispute over the interpretation or performance hereof the
Tribunal de Commerce at Paris shall have sole jurisdiction.

17. FORCE MAJEURE

If either party cannot undertake or continue performance of all or part of its
obligations and intends to avail itself of a claim of force majeure it is
obliged to advise the other party immediately.

It must do so by the most rapid means and confirm by certified letter with
acknowledgment of receipt, providing evidence of the unforeseeable, unavoidable
and external nature of the event that renders it incapable of undertaking or
continuing performance of its obligations.

In any event the affected party must use its best endeavors to remedy the
non-performance of its obligations.



                                       7
<PAGE>



The following shall be deemed to be cases of force majeure :

- Strikes or other social unrest, whatever the cause thereof, even if the
problems can yielding to the workers' demands ;

- Natural disasters, fire, or explosion;

The periods for which performance of the said obligations is delayed shall be
added to the normal term of the Contract, but may not in any circumstances be
greater than 6 months. Beyond that period each of the parties shall have the
right to repudiate the Contract.



DATED December 26 1996
SIGNED AT Paris (two original copies)
For MIDLAND MADISON

/s/ Eric Dalbiez
--------------------------------
ERIC DALBIEZ
For ELF ANTAR FRANCE

/s/ Robert Duchesne
--------------------------------
ROBERT DUCHESNE



                                       8
<PAGE>



                                   RIDER NO. 1
                  CONTRACT FOR THE SUPPLY OF PARISIAN CRUDE OIL
                                   12/26/1996

BETWEEN:

ELF ANTAR FRANCE, a public limited company with a share capital of 1,422,2
15,QOO francs, registered office Tour Elf, 2 place de la Coupole, LA Defense
6,924OO COURBEVOIE, Nanterre company number B 302 556 832 (hereinafter referred
to as " the Purchaser"), represented by Robert DUCHESNE, , acting in his
capacity of Purchasing outlets Manager and duly authorised for the purposes
hereof of the first part

AND MADISON / CHART ENERGY, limited partnership with a capital of I,781,400
francs, registered office situate at 16 Place Vendome, 75001 PARIS, Paris
company number B 391 727 450 (hereinafter referred to as "the Vendor",
represented by Erik DALBIEZ , acting in his capacity of Chief Executive Officer
of Madison Oil France plc, Manager of Madison / Chart Energy, and duly
authorised for the purposes hereof of the second part hereinafter collectively
referred to as "the parties".

It has been agreed as follows:

     A. PURPOSE OF CONTRACT

The contract for the supply of Parisian crude oil dated December 26, 1996 is
hereby amended to take account of the transfer to the Vendor of the EAEPF share
in the wells and concessions at Neocomien as from 01/10/97.

In consequence whereof clauses 1 and 2 of the contract dated December 26, 1996
are henceforth expressed as follows:

1. PURPOSE OF CONTRACT

The Vendor agrees to sell and deliver to the Purchaser, and the Purchaser agrees
to buy from the Vendor, in accordance with the methods and conditions set out
herein, the portion of crude oil production extracted from the concessions held
by the Vendor as set out hereinafter:

                  - CHAMPROSE               100%
                  - CHARMOTTES              100%
                  - NEOCOMIEN               100%

                  (SAINT FIRMIN, CHATEAURENARD, CHUELLES and COURTENAY)

The Vendor may additionally make an offer to the Purchaser by certified letter
with acknowledgment of receipt to buy from it all that part of the production it
is entitled to as new exploration in the Parisian basin for the term of the
contract under the same conditions as those herein for a crude of equivalent
quality. The Purchaser shall have a period of one month from receipt of the
Vendor's request to notify the Vendor by certified letter with acknowledgment of
receipt of its acceptance or rejection of the offer. Should the Purchaser
approve, a rider shall be added to the Contract.

The Vendor may also make an offer to the Purchaser by certified letter with
acknowledgement of receipt to buy from it all its production sourced from the
Vendor's acquisition of already exis the Paris basin, for the term of the
contract under the same conditions as those herein fo equivalent quality. The
purchaser shall have a period of one month from receipt of the request to notify
the Vendor by certified letter with acknowledgment of receipt of its acceptance
or rejection of the offer. Should the Purchaser approve, a rider shall be added
to the Contract.



                                       9
<PAGE>



In the event that the production of crude oil the subject-matter of this
Contract, such as production of crude oil from new operations, should be shared
between several producers, only those portions of the production belonging to
the Vendor shall benefit from then terms hereof. In consequence thereof, the
Vendor agrees to inform the Purchaser by certified letter with acknowledgment of
receipt within one month of any changes of associates and-any change in the
amount of its share in the concession.

In any event the Purchaser shall not be obliged to accept under the terms of
this contract a quantity of crude oil greater than 100,000 metric tonnes per
annum.

2. PRICE

The price P (in French Francs per US barrel of crude oil free of sediment and
water delivered in the Grandpuits refinery crude vats) shall be obtained by
applying the following formula:

                                   P=(A+B+C)xD

A is equal in value to the arithmetic mean of all average daily quotations (spot
assessment) of the Dated Brent published in Platt's Oil Market Wire during month
M + 1 for the month M deliveries.

The value of B is equal to: - 1.60 USD/bbl (minus one dollar and sixty cents
per barrel) for the crude from the fields of:

CHAMPROSE
CHARMOTTES

The value of B is equal to: -2.15 USD/bbl (minus two dollars fifteen cents per
barrel) for the crude from the fields of:

NEOCOMIEN (SAINT FIRMM, CHATEAURENARD, CHUELLES and COURTENAY)

The value of C is equal to 0 for pipeline deliveries and -0.30 USD/bbl (minus
thirty cents per barrel) for truck deliveries.

D is equal in value to the arithmetic mean of all average daily quotations for
the exchange rate in French francs of the US dollar, as indicated by the Banque
de France and subsequently published in the French Republic Official Gazette
during month M+ 1 (for the month M deliveries).

Items A,B,C,D, and P shall be rounded to two decimal places.

     B. EFFECTIVE DATE OF THIS RIDER

This rider shall take effect on October 1, 1997.

The other terms of the contract dated December 26, 1996 shall remain unchanged.

DATED March 30, 1998
SIGNED AT Paris (two copies)
For MADISON / CHART ENERGY For ELF ANTAR FRANCE

/s/ Erik Dalbiez
--------------------------------
ERIK DALBIEZ

/s/ Robert Duchesne
--------------------------------
ROBERT DUCHESNE.



                                       10
<PAGE>



                                   RIDER NO. 2
                TO THE CONTRACT FOR SUPPLY OF PARISIAN CRUDE OIL

BETWEEN:

ELF ANTAR FRANCE, a public limited company having a share capital of 1,422,2
15,000 francs, registered office Tour Elf, 2 place de la Coupole, La Defense
6,924OO COURBEVOIE, Nanterre company number B 302 556 832 (hereinafter referred
to as " the Purchaser"), represented by Patrick NICOLAS, acting in his capacity
of Purchasing Logistics Manager and duly authorised for the purposes hereof of
the first part

AND MADISON / CHART ENERGY, limited partnership with a capital of
1,78 1,400 francs, registered office 13/15 boulevard de la Madeleine, 75001
PARIS, Paris company number B 391 727 450 (hereinafter referred to as "the
Vendor", represented by Etik DALBIEZ , acting in his capacity of Chief Executive
Officer of Madison Oil France plc, Manager of Madison I Chart Energy, and duly
authorised for the purposes hereof of the second part hereinafter collectively
referred to as 'the parties"

It has been agreed as follows:

A. PURPOSE OF THE CONTRACT

The contract for supply of Parisian crude oil dated December 26,1996 and the
rider of March 30,1998 are hereby amended to take account of the following
amendments:

- review of the pricing formula.

- Changes to the payment schedule (dependent on the period for determining
item A)

- Amendment of the contractual payment schedule.

- Insertion of a confidentiality clause,

In consequence whereof clauses 2,4 and 11 of the contract dated December 26,
1996 and the rider of March 30,1998 and the new clause 18 are henceforth
expressed as follows:

"2. PRICE

2.1 The price P (in French Francs per US barrel of crude oil free of sediment
    and water delivered in the Grandpuits refinery crude tanks) shall be
    obtained by applying the following formula: P=(A+B+C)xT/D

2.2 A is equal in value to the arithmetic mean of all average daily quotations
    (spot assessment) of the Dated Brent published in Platt's Oil Market Wire
    during month M for the month M deliveries

2.2 1 For crude from the fields of:

         CHAMPROSE
         CHARMOTTES

The value of B is defined as follows:

B= -l $US/bbl if A be less than or equal to $l0/bbl
B= -A/ $ US l0/bbl if A be greater than $l0/bbl and if A be less than $20/bbl
B= -$ US 2/bbl if A be greater than or equal to $20/bbl

2.22 For crude from the fields of:

NEOCOMIEN (SAINT FIRMM, CHATEAURENARD, CHUELLES and COURTENAY) The value of B is
defined as follows:


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<PAGE>


B= - $ US 1.25/ bbl if A be less than or equal to $l0/bbl
B= -A/ $ US 8/bbl if A be greater than $10/bbl and if A be less than $21/bbl
B= - $ US 2.625 / bbl if A be greater than or equal to $21/bbl

2.3 The value of C is equal to 0 for pipeline deliveries and -0.30 USD/bbl
(minus, thirty cents per barrel) for truck deliveries.

2.4 D is equal in value to the arithmetic mean of all average daily quotations
for the exchange rate in US dollars of the Euro, as indicated by the Banque
Centrale Europbemre and subsequently published in the French Republic Official
Gazette during month M (for the month M deliveries).

2.5 The rate of conversion of the Euro into francs, T = 6.55957 FF/Euro.

2.6 If the Platt quotations and the dollar quotations cease to be published, the
parties shall confer as soon as possible to agree on the necessary amendments to
this contract.

2.7 Rounding rules:

Item D shall be rounded to four decimal places.

If the fifth decimal is greater than or equal to 5, the fourth decimal shall be
rounded up,

If the fifth decimal is less than 5, the fourth decimal shall remain unchanged.

Item A shall be rounded to two decimal places,

Item B shall be rounded to two decimal places,

Item P shall be rounded to two decimal places,

If the third decimal is greater than or equal to 5, the second decimal shall be
rounded up,

If the third decimal is less than 5, the second decimal shall remain unchanged.

2.8 The Purchaser's option with respect to the period for fixing A and D

If during a given month M-l the value A exceeds $15 / bbl the Purchaser shall
have the option of reverting for month M deliveries to a reference period "month
M + 1" for the quotations used in the calculation of A and D. In that case the
Purchaser shall inform the Vendor, by facsimile or certified letter with
acknowledgment of receipt, of the altered reference period before the 8" working
day of month M.

4. INVOICING AND PAYMENT

The Vendor shall make out its invoices on the basis of net quantities expressed
in full barrels and received at refinery by the Purchaser during a given month.
Payment for supply of crude oil under the Contract shall be made in French
francs in France by bank transfer.
Payment shall be made within six working days of the date of issue of the
invoice, which the Vendor agrees to send to the Purchaser by facsimile and post
the same day.

11 TERM OF CONTRACT

This contract shall take effect on 01/03/99 and shall remain in force until
31/12/2002. It may then be renewed automatically for periods of one year unless
notice is given by with acknowledgment of receipt by either of the parties at
least six months before the due date.

18. CONFIDENTIALITY CLAUSE.

Information given by the parties pursuant to this contract must be considered
confidential and may



                                       12
<PAGE>



not in any circumstances given by the Purchaser or the Vendor to third parties,
without the written consent of the other party.

Similarly, all associates of the Purchaser or the Vendor must observe
professional secrecy with respect to all information to which they are privy
pursuant to this contract save with the prior written authority of the other
party.

It is agreed that the confidentiality undertakings as defined in this clause
shall remain valid for the whole term of this contract and remain in force for
two years after the expiration of the said contract."

B. CLAUSES IN FORCE

The other terms of the contract dated December 26, 1996 and the rider dated
March 30, 1998 which are not amended by this rider remain in force.

DATED March 29, 1999
SIGNED AT Paris La Dkfense (two copies)
For MADISON / CHART ENERGY

/s/ Eric Dalbiez
-----------------------------------
Erik DALBIEZ
For ELF ANTAR FRANCE

/s/Patrick Nicolas
-----------------------------------
Patrick NICOLAS



                                       13
<PAGE>
                                   APPENDIX 1
                           INVOICING AND PAYMENT TERMS

1) INVOICING

As of the signature of this Scale Agreement, the Seller shall send the
Purchaser:

     a) an invoice for an amount of USD 9,670,OOO (nine million six hundred and
     seventy thousand United States dollars) to which VAT shall be added. VAT
     shall be calculated on the equivalent in French francs of said sum
     converted at the rate in force as published in the Journal Oficiel
     [Official gazette of laws and regulations] by Banque de France on the date
     of invoicing.

     b) an invoice for an amount of USD 330,000 (three hundred and thirty
     thousand United States dollars).

2) INCOME FROM THE SALE OF CRUDE

As of the signature of this Sale and Assignment Agreement, the Seller shall
cancel all of the invoices made for transitional purposes for quantities of oil
delivered to refinery between 1 October 1997 and 31 May 1998. It shall replace
them with invoices for the same quantities, established on the basis of the
conditions concluded between the Purchaser and Elf Antar France, the amount of
which, calculated in dollars, shall be deducted from the second payment provided
for in Article 3(ii) hereinbelow. The Purchaser shall invoice Elf Antar France
directly for the quantities delivered to refinery as of 1 June 1998.

3) PAYMENT OF THE PRICE

Payment shall be made according to the following terms:

     (i) 1st instalment: within ten working days of the execution of this Sale
     and Assignment Agreement, the Purchaser shall pay the Seller the sum of USD
     330,000 (three hundred and thirty thousand United States dollars)

     (ii) 2nd instalment: within ten working days as of the signature of this
     Sale and Assignment Agreement the Purchaser shall pay the Seller the sum of
     USD 5,670,OOO (five million six hundred and seventy thousand United States
     dollars), from which shall be deducted the income collected by the Seller
     as described in Article 2 hereinabove.

     (iii) Payment of the outstanding balance:

The remainder of the price, i.e. USD 4,000,OOO (four million United States
dollars) (the Balance) shall be the subject of seven half-yearly payments of a
unitary amount of USD 571,400 (five hundred and seventy-one thousand four
hundred United States dollars) adjusted by a coefficient determined by the
arithmetical average (P) of all of the Brent daily spot assessments published in
Platts Oil Market Wider during the previous calendar half-year.



                                       25
<PAGE>


The applicable coefficients, functions of the value of P, shall be as follows:


<Table>
<Caption>
  PRICE PER BARREL            COEFFICIENT
 ------------------           -----------
<S>                               <C>
       P < or = 12.50               0%
  12.5 < P < or = 13.50            15%
  13.5 < P < or = 14.50            35%
  14.5 < P < or = 15.50            55%
  15.5 < P < or = 16.50            70%
  16.5 < P < or = 17.50            85%
  17.5 < P < or = 18.50           100%
  18.5 < P < or = 19.50           120%
  19.5 < P < or = 20.50           140%
  20.5 < P < or = 21.50           160%
  21.5 < P < or = 22.50           180%
       P > 22.50                  200%
</Table>

The seven payments shall fall on the following due dates:

January 31, 1999
July 31, 1999
January 31, 2000
July 31, 2000
January 31, 2001
July 31, 2001
January 31, 2002

On the hypothesis that the application of the preceding conditions does not
allow exhaustion of the Balance and interest on the last due date, namely
January 3 1, 2002, the Purchaser shall pay the Vendor a royalty calculated on
the basis of 2 USD (two dollars) per barrel produced, at an average Brent price
of between USD 17.50 and USD 18.50. Payment of that royalty shall fall on the
following dates :

                  July 31, 2002
                  January 31, 2003
                  July 31, 2003
                  January 31, 2004

The royalty shall be adjusted by a coefficient taking into account of the
average Brent price over-the preceding calendar week, the adjustment
coefficients being the same as those stipulated in the scale above. Royalties
paid shall be deductible from the Balance and no royalty shall be owed and
interest are paid off.

As of January 3 1, 1999 sums owed to the assignor shall be increased by interest
calculated on the basis of the LIBOR plus 1.75%. Interest owing on each due date
shall be calculated on the basis of sums owing on that due date only, the
balance of the interest incurred being payable on the final date, namely January
3 1, 2004.

The Purchaser may accelerate discharge of its debt at any time without penalty.
In the event of lasting decrease or stagnation, over and above current
conditions, of the price at which the Purchaser can release its production,
putting at risk the economic balance of this contract, the Parties shall confer
to modify the conditions contained in this paragraph 3(lii).
VAT owed by the Purchaser on the amount referred to in clause l(a) above shall
be certified as being transferred to Elf Antar France. As soon as Elf Antar
France shall have paid the amount to the Purchaser, the Purchaser shall on the
same day repay the same amount to the assignor.



                                       26
<PAGE>
ELF AQUITAINE EXPLORATION PRODUCTION FRAME

Postal address:
P.O. Box 22-64170 Lacq
Telephone: +33 (0) 5 59 92 22 22
Central telex /Lacq 500 804

                                            MADISON CHART/Energy
                                            13-15 rue de la Madeleine
                                            75001 PARIS
                                            Attention : Mr E. DALBIEZ

Our ref.: EP/F/JUR - OL/No. 00.93
Re: Assignment agreement dated August 20, 1998

Dear Sir,

I am following up our conversations concerning the application of clause 3
"payment" in Schedule 1 (" invoicing and payment procedures") of the assignment
agreement dated August 20, 1998 re interest applicable when paying the balance
of the consideration in 7 instalments before January 3 1,2002, on the dates
specified in the said schedule 1.

In order to settle the issue, EAEPF and Madison CharVEnergy have agreed on the
following method of calculating the interest owing on each of the 5 instalments
accrued or accruing between Jamtary 3 1, 2000 and January 3 1,2002, noting that
calculation of the interest for the instalments between January 3 1, 1999 and
July 3 1 1999 is not in dispute and the said instalments are paid in full.

The sums owing to the assignor on each instalment date are to be increased by
interest calculated on the amount owing for the said in&&rent, as follows:

a) for the six month period leading up to the instalment date the rate of
interest shall be the USD Libor rate six month quote at London two working days
before the commencement of the said six month period plus 1.75%;

b) for the preceding six month periods, commencing on February 1, 1999 and
ending on the eve of the first day of the six month period referred to above in
a), the rate of interest shall be the six month USD Libor rate for each of the
six month periods since January 31 ,1999 previously used to calculate the
interest for payments made on preceding instalment dates with no margin applied;
c) the calculation of interest follows the LIBOR USD market rule: the amount
of interest owing is obtained by dividing the annual interest on a payment by
360 and multiplying the said amount by the number of days in each six month
period including the first and last day of the period being the instalment date
on which payment is due.

The amount of interest, determined in accordance with the aforementioned
conditions, is paid with the consideration payment corresponding to the
instalment date.

The said conditions are used to determine each invoicing of interest. A copy of
an invoice accompanied by an explanatory table showing the breakdown of interest
accrued and due hereto bv wav of illustration: the said invoice regularizes the
amount of interest owing at January 31, 2000 instalment date, for which a
provisional payment has been made of USD 37,486 January 31, 2000 value.



                                       27
<PAGE>



If the whole of then balance and interest be not repaid on January 31,2002, the
said balance shall be repaid by application of payment and instalment dates
provided for in clause 1 of schedule 3 of the contract, together with interest
calculated in accordance with the provisions of paragraphs a), b) and c)
hereinabove.

This contractual letter supplements clause 3 of Schedule No. 1 of the assignment
agreement dated August 20, 1998.

I should be grateful if you would send back the duplicate of this letter with
your signature to indicate your agreement to these conditions.

Yours Faithfully,
DATED July 21, 2000
SIGNED AT Lacq (two copies)
For Elf aquitaine exploration
production france

/s/ C. Gueritte
--------------------
C. GUERITTE

For Madison Chart Energy

/s/ Erik Dalbiez
--------------------
E. DALBIEZ




                                       28