<PAGE>   1
                                                                   EXHIBIT 10.27

             [EOTT ENERGY OPERATING LIMITED PARTNERSHIP LETTERHEAD]

                           CRUDE OIL PURCHASE CONTRACT




                                  March 5, 1999



Coho Marketing & Transportation, Inc.
Attn:  Ms. Anne Marie O'Gorman
14785 Preston Road, Suite 865
Dallas, Texas 75240

            Re:  EOTT Contract No. 52826
                 Coho Contract No.____________

Gentlemen:

When accepted by you in the manner hereinafter indicated, this shall evidence
the agreement ("Agreement") between COHO MARKETING & TRANSPORTATION, INC.,
hereinafter referred to as "Coho" and EOTT ENERGY OPERATING LIMITED PARTNERSHIP,
hereinafter referred to as "EOTT", under the terms of which, and for and in
consideration of the promises made hereunder, such parties shall sell and buy
the hereinafter described crude oil and/or condensate as follows:

I.   TERM:

     Commencing at 7:00 a.m. C.T. on March 1, 1999 through December 31, 1999,
     and continuing annually thereafter, until terminated by either party
     giving the other party written notice of such cancellation prior to
     September 30 for each term.

     If at any time during 1999, or any subsequent renewal period, the floor
     pricing plan is in effect (meaning the price paid under the Agreement is
     the floor price, even if the market did not automatically trigger the floor
     price), EOTT, at its option, may extend the Agreement for an additional one
     year term at the same terms and conditions.

II.  TYPE OF OIL:

     Coho shall deliver to EOTT Mississippi Heavy Sour type of crude oil from
     leases identified on Exhibit "A" or new lease production acceptable to
     EOTT.

III. QUANTITY:

     Coho shall deliver to EOTT a mutually agreed minimum quantity of crude oil,
     with a total calculated monthly from the expected minimum volumes from each
     field, estimated to be approximately 1,185 BPD at 3/1/99. This minimum
     monthly volume will be increased by 5% on April 1, 1999, May 1, 1999, June
     1, 1999 and July 1, 1999 (1,244 BPD for April 1999, 1,306 BPD for May 1999,
     1,371 BPD for June 1999 and 1,440 BPD for July 1999 through end of term).
     Coho may revise the minimum quantity of crude oil to be delivered On a
     monthly basis for any renewal term by providing data to support a volume
     reduction.


<PAGE>   2
IV.  DELIVERY:

     Coho shall deliver at the leases through meters and/or tank gauges into
     EOTT's designated trucks.

V.   PRICE:


     For each barrel of crude oil purchased by EOTT, EOTT shall pay the higher
     of (A) a mutually agreed floor price of $8.50 per barrel or (B) EOTT's
     posted price for West Texas Sour crude oil, gravity delivered, plus $.50
     per barrel ("Posted Price"). For pricing purposes, all crude oil delivered
     hereunder during any calendar month will be considered to have been
     delivered in equal daily quantities during such month.

     The floor price will be an option for payment for each barrel purchased by
     EOTT in any month in which any field reaches its minimum expected volume
     (as set forth on Exhibit "B" attached hereto and made a part hereof). The
     monthly volume will be calculated by EOTT based on the total barrels
     purchased by EOTT from that field by the number of calendar days in the
     month.

     For any month in which the floor price is an option for payment and the
     minimum monthly volumes have not been met by Coho, before determining which
     price is higher, the floor price will be reduced by the percentage of the
     under delivery. For example, if the minimum monthly volume is 1,000
     barrels, but actual deliveries from that field total 900 barrels, the price
     to be paid per barrel shall be the higher of (A) 90% of the floor price or
     (B) the Posted Price.

     If, for any subsequent renewal period, Coho does not elect to renew the
     floor price option of the pricing provision, all crude oil will be paid at
     the Posted Price.

VI.  PAYMENT:

     Payment shall be made pursuant to open division orders, executed by each
     party, less taxes, payable by check on the twentieth (20th) day of the
     month following the month of delivery. In the event the payment due date
     falls on a Saturday or a bank/Federal holiday other than a Monday, payment
     shall be due on the last preceding business day. Should the payment due
     date fall on a Sunday or a Monday bank/Federal holiday, payment shall be
     due on the following business day.

VII. DIVISION ORDERS:

     All division orders, division order documents and division order matters
     shall be sent to the following addresses:

<TABLE>
<CAPTION>
<S>                                             <C>
     EOTT Energy Operating Limited Partnership  Coho Marketing & Transportation, Inc.
     ATTN: Division Order Department            ATTN; Division Order Department
     P.O. BOX 4666                              14785 Preston Road, Suite 860
     HOUSTON. TX 77210-4666                     Dallas, Texas 75240
</TABLE>

     If any division orders are executed pursuant to this Agreement, and in the
     event of any irreconcilable conflict between the terms of any such division
     orders and this Agreement, the terms of this Agreement shall be deemed
     controlling, even if the division orders are dated subsequent to this
     Agreement.
<PAGE>   3

VIII.  INVOICES:

       Invoices and any other invoicing matters/documents shall be mailed to the
       following addresses:

<TABLE>
<CAPTION>
<S>                                                 <C>
       EOTT Energy Operating Limited Partnership    Coho Marketing & Transportation, Inc.
       ATTN: Crude Oil Accounting                   ATTN:________________________
       P.O. Box 4666                                14875 Preston Road, Suite 860
       Houston, TX 77210-4666                       Dallas, Texas 75240
</TABLE>

IV.    SPECIAL PROVISIONS:

       A.  All crude oil delivered to EOTT hereunder will be crude oil delivered
           in accordance with the quality standards set forth herein [NOTE: We
           either have to attach the General Provisions from the first contract
           or insert quality standards], and Coho shall fully indemnify EOTT
           against and hold EOTT harmless from any loss, damage, harm,
           liability, claim, action, suit, demand or complaint of any nature
           whatsoever, which EOTT may suffer as a result of receiving
           non-standard crude oil from Coho at the point of title transfer set
           forth herein as a consequence of Coho's intentional addition in any
           such crude oil of any contaminant.

       B.  Coho represents and warrants to EOTT that it has full right and
           authority to enter into this Agreement for all of the crude oil
           committed by Coho hereunder and that Coho is violating no duty or
           obligation which it may have with any third party by entering into
           this Agreement.

       C.  Coho shall fully defend and indemnify EOTT against, and hold EOTT
           fully harmless from, any claim, action, suit, demand or complaint (of
           any nature whatsoever) which any governmental entity or any interest
           owner in any well or lease from which the crude oil delivered to EOTT
           was produced may bring in connection with (i) Coho's ability to enter
           into this Agreement with EOTT, or (ii) any production proceeds out by
           EOTT pursuant to this Agreement.

       D.  Neither party shall assign this Agreement to any person or firm
           except upon written consent by the other party, including credit
           approval, which consent shall not be unreasonably withheld. This
           Agreement shall be binding upon and inure to the benefit of the
           parties hereto, their respective heirs, representatives, successors
           and assigns.

       Please confirm your acceptance of, and agreement with, this transaction
by signing below in the space provided and return facsimile to 601-969-6516
within the next 48 hours, followed by return by regular mail. If we have not
heard from you to the contrary within the foregoing time frame, your acceptance
will be presumed.

Very truly yours,

EOTT ENERGY OPERATING LIMITED PARTNERSHIP
By: EOTT Energy Corp., its General Partner


By: /s/ DAN E. COLE
   -------------------------------
Name: Dan E. Cole
     -----------------------------
Title: Regional Business Manager
      ----------------------------
Fax:  (601) 969-6516
    ------------------------------

<PAGE>   4
AGREED TO AND ACCEPTED THIS 1 DAY OF APRIL, 1999 BY:

COHO MARKETING & TRANSPORTATION, INC.


By: /s/ ANNE MARIE O'GORMAN
   -----------------------------
Name:   Anne Marie O'Gorman
     ---------------------------
Title:  Sr. Vice President
      --------------------------
Fax:
    ----------------------------