<PAGE>

                         AGREEMENT AMONG STOCKHOLDERS

     This Agreement Among Stockholders (this "Agreement") dated October 15,
1999, is by and among Quicksilver Resources Inc., a Delaware corporation (the
"Company"), Mercury Exploration Company, a Texas corporation ("Mercury"),
Quicksilver energy, L.C., a Michigan limited liability company ("QELC"), Frank
Darden, Thomas F. Darden, Glenn Darden, Anne Darden Self, and Joint Energy
Development Investments Limited Partnership, a Delaware limited partnership
("JEDI").

     WHEREAS, except for the Company, the parties hereto (collectively the
"Stockholders" and each, a "Stockholder") are holders of shares of the Company's
common stock, par value $.01 per share (the "Common Stock"); and

     WHEREAS, the parties hereto and others were parties to that certain
Stockholders Agreement dated April 9, 1998 as amended by Amendment No. 1 dated
September 1, 1998 (as so amended, the "Stockholders Agreement");

     NOW, THEREFORE, in consideration of the execution and delivery by each of
the parties hereto of the Termination Agreement of even date herewith,
terminating the Stockholders Agreement, the parties hereto agree as follows:

     1.   Board Representation.

          (a)  The Company, subject to its fiduciary duties under applicable
state law, and each of the Stockholders agree and acknowledge that JEDI and/or
its Permitted Transferees (defined below) shall have the right, exercisable at
any time and acting alone (or, if more than one, in concert with each other), to
elect one or more members of the Board of Directors of the Company as determined
below, until such time (the "Termination Date") as JEDI and/or its Permitted
Transferees have transferred in the aggregate 1,340,405 shares of Company Stock
to one or more persons other than Permitted Transferees. The number of directors
that JEDI and/or its Permitted Transferees shall be entitled to elect shall be
that number of directors that represents a percentage of the entire Board of
Directors at the time of election that is as close as possible to the percentage
of outstanding shares of Common Stock then held collectively by JEDI and/or its
Permitted Transferees. In calculating that percentage, the number of outstanding
shares of Common Stock held by JEDI and/or its Permitted Transferees shall not
exceed 1,340,405 shares less any number of shares theretofore transferred by
JEDI and/or its Permitted Transferees to one or more persons other than
Permitted Transferees. In no case before the Termination Date shall JEDI and/or
its Permitted Transferees be entitled to elect less than one director. Any
director elected by JEDI and/or its Permitted Transferees pursuant to this
Section 1 may be removed only by JEDI and/or its Permitted Transferees and any
vacancy resulting from the resignation, removal or death of any director elected
by JEDI and/or its Permitted Transferees may be filled only by JEDI and/or its
Permitted Transferees, and neither the Company nor any Stockholder other than
JEDI and/or its Permitted Transferees shall take any action to remove any such
director or fill any such vacancy.

          (b)  In order to facilitate the rights of JEDI and/or its Permitted
Transferees set forth in paragraph (a) of this Section 1, each of the
Stockholders other than JEDI hereby grants to JEDI its proxy, which (being
coupled with an interest) shall be irrevocable, to take any of the following
actions, either by written consent or at a meeting of the Company's
stockholders: (i) to elect the number of directors that JEDI and/or its
Permitted Transferees are entitled to elect pursuant to

<PAGE>

paragraph (a) of this Section 1; (ii) to remove a director elected by JEDI
and/or its Permitted Transferees; and (iii) to fill any vacancy on the Board of
Directors resulting from the removal, resignation or death of a director elected
by JEDI and/or its Permitted Transferees. The proxy granted hereby shall
terminate upon the termination of JEDI's and/or its Permitted Transferees's
right to elect directors pursuant to paragraph (a) of this Section 1.

     2.   Tag Along Rights; Limitation on Transfers by Certain Stockholders.
Each of Mercury and QELC (collectively the "Restricted Stockholders", and each,
a "Restricted Stockholder") agrees that until the Termination Date such
Restricted Stockholder will not transfer any shares of Common Stock without
first providing JEDI and/or its Permitted Transferees the right to join in such
transfer in accordance with the following provisions:

               (1)  If a Restricted Stockholder desires to transfer shares of
Common Stock (a "Proposed Transfer") the Restricted Stockholder shall cause the
proposed transferee (the "Proposed Transferee") to make a written offer (the
"Offer") to JEDI and/or its Permitted Transferees to purchase, on the same terms
offered to the Restricted Stockholder, from JEDI and/or its Permitted
Transferees a number of shares of Common Stock (rounded to the nearest whole
number of shares) (the "Offered Shares") equal to the product of (A) a fraction
the numerator of which is the number of shares of Common Stock then held
collectively by JEDI and/or its Permitted Transferees but not to exceed
1,340,405 shares less any number of shares theretofore transferred by JEDI
and/or its Permitted Transferees to one or more persons other than Permitted
Transferees and the denominator of which is the total number of then outstanding
shares of Common Stock and (B) the total number of shares of Common Stock to be
purchased from the Restricted Stockholder in the Proposed Transfer.  The Offer
shall specify the total number of shares of Common Stock to be purchased from
the Restricted Stockholder, the per share consideration to be paid and the other
terms of the Proposed Transfer, including the closing date for the Proposed
Transfer, which shall not be less than twenty days nor more than ninety days
after the date the Offer is received by JEDI and/or its Permitted Transferees.

               (2)  JEDI and/or its Permitted Transferees shall have the right,
for a period of twenty days following receipt of an Offer, to elect to accept
the Offer with respect to all or a portion of the Offered Shares by delivering
to the Proposed Transferee within such twenty-day period a written acceptance
(an "Acceptance") of the Offer, specifying the number of shares to be
transferred by JEDI and/or its Permitted Transferees.  The number of shares of
Common Stock to be transferred by the Restricted Stockholder in the Proposed
Transfer shall be reduced by the number of shares of Common Stock to be
transferred by JEDI and/or its Permitted Transferees in the Proposed Transfer.
Closing of the Proposed Transfer shall be made on reasonable terms specified in
the Offer, which terms shall include only those terms that are customary in
transactions similar to the Proposed Transfer.  If JEDI and/or its Permitted
Transferees does not deliver an Acceptance within twenty days after receipt of
an Offer, the Offer shall expire.

     3.   Certain Shares Held by Mercury; Agreement Does Not Apply.
Notwithstanding anything in this Agreement to the contrary, this Agreement does
not apply to 1,340,405 shares of the Common Stock now owned by Mercury (the
"Excepted Shares").  Mercury may transfer all or any portion of the Excepted
Shares at any time or from time to time without restriction, and the transferees
will have no rights or obligations under this Agreement.  Shares of Common Stock
that

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<PAGE>

are transferred by Mercury pursuant to a transaction in which JEDI and/or its
Permitted Transferees have been given the right to join under Section 2 shall
not be deemed Excepted Shares.

        4.      Legend on Certificates; Stop Transfer Orders.  The parties
hereto agree to the placement on certificates representing shares of Common
Stock (other than Excepted Shares) of a legend indicating that such securities
are subject to the terms of this Agreement. In addition, Mercury and QELC agree
to the placement on certificates representing shares of Common Stock owned by
them (other than Excepted Shares) of a legend indicating that such securities
may not be transferred except in accordance with this Agreement and to the entry
of a stop transfer order with the transfer agent for such securities against the
transfer of such securities except in accordance with this Agreement.

        5.      Miscellaneous.

                (a)  This Agreement shall inure to the benefit of and be binding
upon the successors and assigns of the parties hereto, except that no transferee
of Common Stock from JEDI and/or its Permitted Transferees (except Permitted
Transferees) shall have any rights or obligations hereunder and no transferee
(except Permitted Transferees) of Common Stock from any party shall have any
rights or obligations under Section 2.

                (b)  Each of the parties hereto acknowledges and agrees that the
other parties would be damaged irreparably in the event any of the provisions of
this Agreement are not performed in accordance with their specific terms or
otherwise are breached. Accordingly, each of the parties agrees that the other
parties shall be entitled to an injunction or injunctions to prevent breaches of
the provisions of this Agreement and to enforce specifically this Agreement and
the terms and provisions hereof in any action instituted in any court of the
United States or any state thereof having jurisdiction over the parties and the
matter in addition to any other remedy to which it may be entitled, at law or in
equity, and if any action should be brought in equity to enforce any of the
provisions of this Agreement, none of the parties hereto shall raise the defense
that there is an adequate remedy at law.

                (c)  This Agreement may be executed in any number of
counterparts and by different parties hereto in separate counterparts, each of
which counterparts, when so executed and delivered, shall be deemed to be an
original and all of which counterparts, taken together, shall constitute but one
and the same Agreement.

                (d)  The headings in this Agreement are for convenience of
reference only and shall not limit or otherwise affect the meaning hereof.

                (e)  The laws of the State of Texas shall govern this Agreement
without regard to principles of conflict of laws.

                (f)  Any provision of this Agreement that is prohibited or
unenforceable in any jurisdiction shall, as to such jurisdiction, be ineffective
to the extent of such prohibition or unenforceability without invalidating the
remaining provisions hereof or affecting or impairing the validity or
enforceability of such provision in any other jurisdiction.

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<PAGE>

        (g)     All notices and other communications provided for or permitted
hereunder shall be made in writing by telecopy, courier service or personal
delivery at the respective addresses of the parties as shown in Section 9(j) of
the Stockholders Agreement or to such other address as any such party may
designate by notice in the manner provided above.  All notices and other
communications to a Permitted Transferee will be given to such party and to such
address as JEDI shall have notified all other parties hereto in writing.  All
such notices shall be deemed to have been delivered and received at the time
delivered by hand, if personally delivered, when receipt acknowledged, if
telecopied, and on the next business day, if timely delivered to an air courier
guaranteeing overnight delivery.

        (h)     The obligations of the parties to this Agreement are several and
not joint, and no party shall be liable for a breach by any other party of such
other party's obligations hereunder.

        (i)     This Agreement may be amended only by means of a written
amendment signed by all of the parties hereto.

        (j)     All references in this Agreement to shares of Common Stock shall
apply to such shares as adjusted to take into account subdivisions,
distributions, reclassifications, and stock splits, dividends or combinations.

        (k)     As used in this Agreement the term "Permitted Transferee" shall
mean (i) an Affiliate (defined below) of JEDI to which JEDI or another of its
Affiliates shall have transferred all or any portion of the 1,340,405 shares of
Common Stock held by JEDI on the date of this Agreement, (ii) any transferee
from JEDI of all or any portion of such shares by operation of law or judicial
decree and (iii) Mercury if JEDI transfers shares of Common Stock to it pursuant
to the Stock Transfer Agreement between them dated April 9, 1998, as amended.
For purposes of this Agreement, "Affiliate," when used to refer to Affiliates of
JEDI, shall exclude the Company and its Affiliates.  As used herein "Affiliate"
of any person means any other person directly or indirectly controlling,
controlled by or under direct or indirect common control with such person.  For
purposes of this definition "control" when used with respect to any person,
means the power to direct the management and policies of such person, whether
through the ownership of voting securities, by contract or otherwise, and the
terms "controlling" and "controlled" have correlative meanings.

        Executed effective as of the date first written above.




                                QUICKSILVER RESOURCES INC.


                                By:  /s/ Glenn Darden
                                     ---------------------------
                                Name:    Glenn Darden
                                     ---------------------------
                                Title:   President
                                     ---------------------------







                                     4


<PAGE>

                                MERCURY EXPLORATION COMPANY


                                By: /s/ FRANK DARDEN
                                   ------------------------------
                                Name: Frank Darden
                                     ----------------------------
                                Title: Chairman
                                      ---------------------------

                                QUICKSILVER ENERGY, L.C.


                                By: /s/ GLENN DARDEN
                                   ------------------------------
                                Name: Glenn Darden
                                     ----------------------------
                                Title: Administrative Manager
                                      ---------------------------


                                JOINT ENERGY DEVELOPMENT
                                INVESTMENTS LIMITED PARTNERSHIP

                                By:  Enron Capital Management Limited
                                     Partnership, its general partner

                                By:  Enron Capital Corp.,
                                     its general partner

                                By: /s/ MARK WARNER
                                   ------------------------------
                                Name: Mark Warner
                                     ----------------------------
                                Title: Agent and Attorney-in-fact
                                      ---------------------------


                                       5
<PAGE>



                                        /s/ Frank Darden
                                        -------------------------
                                        Frank Darden


                                        /s/ Thomas F. Darden
                                        -------------------------
                                        Thomas F. Darden


                                        /s/ Glenn M. Darden
                                        -------------------------
                                        Glenn M. Darden


                                        /s/ Anne Darden Self
                                        -------------------------
                                        Anne Darden Self








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