<PAGE>   1


                                                                   EXHIBIT 4.9

THE WARRANT REPRESENTED HEREBY AND THE STOCK OR OTHER SECURITIES ISSUABLE UPON
THE EXERCISE HEREOF HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
AS AMENDED (THE "ACT"), OR ANY STATE SECURITIES LAWS AND NEITHER SUCH WARRANT
NOR THE STOCK OR OTHER SECURITIES ISSUABLE UPON THE EXERCISE HEREOF NOR ANY
INTEREST THEREIN MAY BE TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AM
EXEMPTION THEREFROM UNDER SUCH ACT AND SUCH LAWS AND THE RULES AND REGULATIONS
THEREUNDER

                          WARRANT TO PURCHASE SHARES
               OF COMMON STOCK OF NORTON DRILLING SERVICES, INC.

This certifies that Norton Family Trust ("Holder"), for value received, is
entitled to purchase from Norton Drilling Services, Inc., a Delaware corporation
(the "Company"), six thousand four hundred (6,400) fully paid and nonassessable
shares of (Common Stock, par value $0.01 per share of the Company (the "Common
Stock"), at a price of $3.125 per share, as adjusted pursuant to Section 3 below
(the "Stock Purchase Price"), at any time or from time to time on or after the
Commencement Date (as defined below) but not later than 5:00 p.m.. (Lubbock,
Texas time) on the Expiration Date (as defined below), upon surrender to the
Company at its principal office at 5211 Brownfield Highway, Suite 230, Lubbock,
Texas 79407 (or at such other location as the Company may advise Holder in
writing) of this Warrant with the Form of Stock Subscription attached hereto as
Exhibit A duly filled in and signed and upon payment of the aggregate Stock
Purchase Price for the number of shares for which this Warrant is being
exercised determined in accordance with the provisions hereof (the "Aggregate
Stock Purchase Price"), in cash, by certified or official bank check, by wire
transfer, or by any combination of the foregoing, as Holder may elect, in its
sole discretion. In lieu of paying the Aggregate Stock Purchase Price upon
exercise of this Warrant, for so long as the Common Stock is publicly traded,
Holder may elect a "cashless exercise" in which event Holder will receive upon
exercise of this Warrant a reduced number of shares of Common Stock equal to (i)
the number of Shares of Common Stock that would be issuable pursuant to this
warrant upon payment of the Aggregate Stock Purchase Price minus (ii) the number
of shares of Common Stock that have an aggregate fair market value equal to the
Aggregate Stock Purchase Price. For purposes of the preceding sentence, the fair
market value of a share of Common Stock shall mean the last reported sale price
of the Common Stock on the last business day preceding the date of exercise. The
Stock Purchase Price and the number of shares purchasable hereunder are subject
to adjustment as provided in Section 3 of this Warrant. "Commencement Date"
means April 1, 1997. "Expiration Date" means April 1, 2002.

This Warrant is subject to the following terms and conditions;

1. Exercise; Issuance of Certificates; Payment for Shares. This Warrant is
exercisable at the option of Holder at any time or from time to time on or after
the Commencement Date but not later than the Expiration Date for all or a
portion of the shares of Common Stock which may be purchased hereunder. Upon
exercise of this Warrant, the Company shall issue and deliver to Holder shares
of Common Stock. The Company agrees that the shares of Common Stock to be
purchased under this Warrant shall be and are deemed to be issued to Holder as
the record owner of such shares as of the close of business on the date on which
this Warrant shall have been surrendered and payment made for such shares.
Subject to the provisions of Section 2, certificates for the shares of Common
Stock so purchased, together with any other securities or property to which
Holder is entitled upon such exercise, shall be delivered to Holder by the
Company or the Company's transfer agent at the Company's expense within a
reasonable time (but in no event more than ten days) after the rights
represented by this warrant have been exercised. Each stock certificate so
delivered shall be in such denominations and classes of Common Stock as may be
requested by Holder and shall be registered in the name of Holder or such other
name as shall be designated by Holder, subject to the limitations




<PAGE>   2


contained in this Section 1, Section 2 and Section 6. If, Upon exercise of this
Warrant, fewer than all of the shares of Common Stock evidenced by this Warrant
are purchased prior to the Expiration Date, one or more new warrants
substantially in the form of, and on the terms in, this Warrant will be issued
for the remaining number of shares of Common Stock not purchased upon exercise
of this Warrant.

2. Shares to be Fully Paid: Reservation of Shares. The Company covenants and
agrees that all shares of Common Stock which may be issued upon the exercise of
the rights represented by this Warrant (the "Warrant Shares") will be, upon
payment of the Stock Purchase Price therefor and issuance thereof, duly
authorized, validly issued, fully paid and nonassessable and free from all
preemptive rights of any stockholder and free of all taxes, liens and charges
with respect to the issue thereof. The Company further covenants and agrees that
during the period within which the rights represented by this Warrant may be
exercised, the Company will at all times have authorized and reserved, for the
purpose of issue or transfer upon exercise of the subscription rights evidenced
by this Warrant, a sufficient number of shares of authorized but unissued Common
Stock for such exercise. The Company will take all such action as may be
necessary to assure that such shares of Common Stock may be issued as provided
herein without violation of any applicable law or regulation, or of any
requirement of any securities exchange or automated quotation system upon which
the Common Stock may be listed.

3. Adjustment of Stock Purchase Price and Number of Shares. The Stock Purchase
Price and the number of shares purchasable upon the exercise of this Warrant
shall be subject to adjustment from time to time upon the occurrence of certain
events described in this Section 3. Upon each adjustment of the Stock Purchase
Price, the holder of this Warrant shall thereafter be entitled to purchase, at
the Stock Purchase Price resulting from such adjustment, the number of shares
obtained by multiplying the Stock Purchase Price in effect immediately prior to
such adjustment by the number of shares purchasable pursuant hereto immediately
prior to such adjustment, and dividing the product thereof by the Stock Purchase
Price resulting from such adjustments.

3.1 Subdivision or Combination of Common Stock. In case the Company shall at any
time subdivide its outstanding shares of Common Stock into a greater number of
shares, the Stock Purchase Price in effect immediately prior to such subdivision
shall be proportionately reduced, and the number of shares issuable upon
exercise of this Warrant shall be proportionately increased. Conversely, in case
the outstanding shares of Common Stock of the Company shall be combined into a
smaller number of shares, the Stock Purchase Price in effect immediately prior
to such combination shall be proportionately increased and the number of shares
issuable upon exercise of this Warrant shall be proportionately reduced.

3.2 Certain Dividends and Distributions. In case the Company shall at any time
declare or pay a dividend upon its Common Stock payable in shares of Common
Stock, the Stock Purchase Price in effect immediately prior to such dividend
shall be proportionately reduced and the number of shares issuable upon exercise
of this Warrant shall be proportionately increased. In case the Company shall at
any time declare or pay a dividend or other distribution on its Common Stock
payable in cash or in evidences of indebtedness, shares of stock or other
securities or property (other than in Common Stock or "Convertible Securities,"
as defined in Section 3.3.1(a)) or in rights, warrants or options to subscribe
for or purchase evidences of indebtedness, shares of stock or other securities
or property (other than "Options," as defined in Section 3.3.1(b)), the Stock
Purchase Price in effect immediately prior to such dividend or other
distribution shall be reduced by the fair market value of such dividend or other
distribution applicable to one share of Common Stock.


<PAGE>   3







3.3 Dilutive Issuances. If the Company shall sell or issue (or shall be deemed
pursuant to Section 3.3.2.3 to sell or issue) at any time after the date of this
Warrant and prior to the termination or expiration of this Warrant, shares of
Common Stock without consideration or for consideration per share less than the
Stock Purchase Price in effect on the date of and immediately prior to such sale
or issuance, then, upon such sale or issuance (or deemed sale or issuance), such
Stock Purchase Price shall be reduced concurrently with such sale or issuance to
a Stock Purchase Price (calculated to the nearest cent) determined by dividing

(a) an amount equal to (i) the total number of shares of Stock Outstanding (as
defined by law) immediately prior to such sale or issuance multiplied by the
Stock Purchase Price, plus (ii) the aggregate of the amount of all
consideration, if any, received or deemed received pursuant to subsection
3.3.2.3 by the Company for such sale or issuance, by

(b) the total number of shares of Stock Outstanding immediately after such sale
or issuance.

No adjustment in the Stock Purchase Price shall be made in respect of the sale
or issuance (or deemed sale or issuance) of additional Stock unless the
consideration per share for such additional Stock sold or issued (or deemed to
be sold or issued) by the Company is less than the Stock Purchase Price in
effect on the date of, and immediately prior to, such sale or issuance. No
adjustment in the Stock Purchase Price shall be made which would increase the
Stock Purchase Price in effect immediately prior to such adjustment, except as
provided in Section 3.3.3 and 3.3.4.

3.3.1 Definitions. For purposes of this Section 3.3, the following definitions
shall apply:

(a) "Convertible Securities" shall mean any indebtedness, shares of stock or
other securities convertible into or exchangeable for Common Stock.

(b) "Options" shall mean any rights, warrants or options to subscribe for or
purchase Common Stock or Convertible Securities.

(c) "Stock Outstanding" shall mean the aggregate of all Common Stock outstanding
and all Common Stock previously deemed issued pursuant to Section 3.3.2.3 at a
price which was less than the Stock Purchase Price in effect on the date of and
immediately prior to such issuance, and as a result of which the Stock Purchase
Price was reduced.

3.3 2 Other Rules. For the purposes of this Section 3.3, the following
provisions also shall be applicable:

3.3.2.1 Cash Consideration. In case of the issuance or sale of additional Common
Stock for cash, the consideration received by the Company therefor shall be
deemed to be the amount of cash received by the Company for such shares (or, if
such shares are offered by the Company for subscription, the subscription price,
or, if such shares are sold to underwriters or dealers for public offering
without a subscription offering, the public offering price), without deducting
therefrom any compensation or discount paid or allowed to underwriters or
dealers or others performing similar services or for any expenses incurred in
connection therewith, but excluding amounts paid or payable by the Company for
interest or dividends accrued at the time of such issuance or sale. In the case
of the issuance or sale for cash of units consisting of shares of Common Stock
and warrants, the portion of the consideration received by the Company for the
unit allocated to the warrant shall equal the value of the warrant ascribed
thereto pursuant to the Black Scholes method of valuation and the balance of the
consideration shall be allocated to the Common Stock.



<PAGE>   4


3.3.2.2 Non-Cash Consideration. In case of the issuance (otherwise than upon
conversion or exchange of Convertible Securities) or sale of additional Common
Stock Options or Convertible Securities for a consideration other than cash or a
consideration a part of which shall be other than cash, the fair market value of
such consideration as determined by the Board of Directors of the Company in the
good faith exercise of its reasonable business judgment, irrespective of the
accounting treatment thereof, shall be deemed to be the value, for purposes of
this Section 3, of the consideration other than cash received by the Company for
such securities.

3.3.2.3 Options and Convertible Securities. In case the Company shall, at any
time after the date of this Warrant, in any manner issue or grant any Options or
any Convertible Securities or shall fix a record date for the determination of
holders of any class of securities entitled to receive any such Options or
Convertible Securities, then the total maximum number of shares of Common Stock
issuable upon the exercise of such Options or upon conversion or exchange of the
total maximum amount of such Convertible Securities at the exercise such
Convertible Securities first become convertible or exchangeable shall (as of the
date of issue or grant of such Options or, in the case of the issue or sale of
Convertible Securities, as of the date of such issue or sale or, in the case
such a record date shall have been fixed, as of the close of business on such
record date) be deemed to be issued and to be outstanding for the purpose of
this Section 3.3 (except that shares of Common Stock shall not be deemed to have
been issued and to be outstanding unless the consideration per share (determined
pursuant to this Section 3.3) of such shares of Common Stock would be less than
the Stock Purchase Price in effect on the date of and immediately prior to such
issuance, or such record date, as the case may be), and to have been issued for
the sum of the amount (if any) paid for such Options or Convertible Securities
and the minimum additional amount (if any) payable upon the exercise of such
Options or upon conversion or exchange of such Convertible Securities at the
time such Convertible Securities first become convertible or exchangeable;
provided that, subject to the provisions of Section 3.3.3, no further adjustment
of the Stock Purchase Price shall be made upon the actual issuance of any such
Common Stock or upon the exercise of any such Option or upon the conversion or
exchange of any such Convertible Securities.

3.3.3 Change in Option Price or Conversion Rate. If the purchase price provided
for in any Option referred to in subsection 3.3.2.3, or the additional
consideration (if any) payable upon the conversion or exchange of any
Convertible Securities referred to in subsection 3.3.2.3, or the rate at which
any Convertible Securities referred to in subsection 3.3.2.3 are convertible
into or exchangeable for shares of Common Stock, shall change at any time
(including changes under or by reason of provisions designed to protect against
dilution), then the Stock Purchase Price in effect at the time of such event
shall forthwith be readjusted to the Stock Purchase Price that would have been
in effect at such time had such Options or Convertible Securities still
outstanding provided for such changed purchase price, additional consideration
or conversion rate, as the case may be, at the time initially granted, issued or
sold; provided that if such readjustment is an increase in the Stock Purchase
Price, such readjustment shall not exceed the amount (as adjusted by Sections
3.1, 3.2 and 3.3) by which the Stock Purchase Price was decreased pursuant to
Section 3.3 upon the issuance of the Option or Convertible Security.

3.3.4 Termination of Option or Conversion Rights. In the event of the
termination or expiration of any right to purchase Common Stock under any Option
granted after the date of this Warrant or of any right to convert or exchange
Convertible Securities issued after the date of this Warrant, the



<PAGE>   5



Stock Purchase Price shall, upon such termination, be readjusted to the Stock
Purchase Price that would have been in effect at the time of such expiration or
termination had such Option or Convertible Security, to the extent outstanding
immediately prior to such expiration or termination, never been issued, and the
shares of Common Stock issuable thereunder shall no longer be deemed to be Stock
Outstanding; provided, that if such readjustment is an increase in the Stock
Purchase Price, such readjustment shall not exceed the amount (as adjusted by
Sections 3.1, 3.2 and 3.3) by which the Stock Purchase Price was decreased
pursuant to Section 3.3 upon the issuance of the Option or Convertible Security.

3.3.5 No Impairment. The Company will not by amendment of its Certificate of
Incorporation or through any reorganization, transfer of assets, merger,
dissolution, issue or sale of securities or any other action, avoid or seek to
avoid the observance or performance of any of the terms to be observed or
performed under this Section 3.3 by the Company, but will at all times in good
faith assist in the carrying out of all the provisions of this Section 3.3 and
in the taking of all such action as may be necessary or appropriate in order to
protect the rights of the holders of this Warrant against impairment. If any
event shall occur as to which the provisions of this Section 3 shall not be
strictly applicable, but with respect to which the failure to make any
adjustment to the Stock Purchase Price and the number of shares purchasable upon
exercise of this Warrant would not fairly protect the purchase rights
represented by the Warrant in accordance with the intent and principles of this
Section 3, upon request of the Holder and at the expense of the Company, the
Company shall appoint a firm of independent public accountants reasonably
acceptable to the Holder which shall give its opinion upon the adjustments, if
any, consistent with the intent and principles established in this Section 3
necessary to preserve without dilution the purchase rights represented by this
Warrant; provided, however, if such accountants shall agree that the adjustments
initially proposed by the Company were correct, then such Holder shall pay the
reasonable fees and expenses of such accountants. Upon receipt of such opinion,
the Company will promptly mail a copy thereof to the Holder and shall make the
adjustments (if any) deserved therein.

3.4 Excluded Events. Notwithstanding anything in this Section 3 to the contrary,
the Stock Purchase Price shall not be adjusted by reason of shares of Common
Stock issued or issuable:

(A) to officers, directors or employees of, or consultants to, the Company
pursuant to stock options outstanding on the date hereof or stock options
granted after the date hereof on terms approved by the Board of Directors of the
Company; and

(B) upon the exercise of any warrants issued to the Holder.

3.5 Notice of Adjustment. Upon any adjustment of the Stock Purchase Price or any
increase or decrease in the number of shares purchasable upon the exercise of
this Warrant, the Company shall give written notice thereof, by first class mail
postage prepaid, addressed to the registered holder of this Warrant at the
address of such holder as shown on the books of the Company. The notice shall be
signed by the Company's chief financial officer and shall state the effective
date of the adjustment and the Stock Purchase Price resulting from such
adjustment and the increase or decrease if any, in the number of shares
purchasable at such price upon the exercise of this Warrant, setting forth in
reasonable detail the method of calculation and the facts upon which such
calculation is based.

3.6 Other Notices. If at any time;

(a) the Company shall propose to declare any cash dividend upon its Common
Stock;

<PAGE>   6


(b) the Company shall propose to declare or make any dividend or other
distribution to the holders of its Common Stock, whether in cash, property or
other securities;

(c) the Company shall propose to effect any reorganization or reclassification
of the capital stock of the Company or any consolidation or merger of the
Company with or into another corporation or any sale, lease or conveyance of
all or substantially all of the assets of the Company; or

(d) the Company shall propose to effect a voluntary or involuntary dissolution,
liquidation or winding-up of the Company;

then, in any one or more of said cases, the Company shall give, by certified or
registered mail, postage prepaid, addressed to the holder of this Warrant at the
address of such holder as shown on the books of the Company, (i) at least 30
days' prior written notice of the date on which the books of the Company shall
close or a record shall be taken for such dividend or distribution or for
determining rights to vote in respect of any such reorganization,
reclassification, consolidation, merger, sale, lease, conveyance, dissolution,
liquidation or winding-up, and (ii) in the case of any such reorganization,
reclassification, consolidation, merger, sale, lease, conveyance, dissolution,
liquidation or winding-up, at least 30 days' written notice of the date when the
same shall take place. Upon the occurrence of an event described in clause (c),
the holder of this Warrant shall be entitled thereafter to receive upon exercise
of this Warrant the kind and amount of shares of stock or other securities or
assets, which the holder would have been entitled to receive after the
occurrence of such event had this Warrant been exercised immediately prior to
such event; and in any such case, appropriate provision shall be made with
respect to the rights and interests of the holder to the end that the provisions
of this Warrant (including, without limitation, provisions with respect to
changes in and adjustments of the Stock Purchase Price and the number of shares
purchasable upon the exercise of this Warrant, and provisions relating to the
receipt by the holder of nonvoting stock convertible into voting stock) shall
thereafter be applicable, as nearly as may be, in relation to any shares of
stock, or other securities or assets, thereafter deliverable upon the exercise
of this Warrant. The Company will not effect any of the transactions described
in clause (c) above unless, prior to the consummation thereof, each person
(other than the Company) that may be required to deliver any cash, stock,
securities or other assets upon the exercise of this Warrant as provided herein
shall assume, by written instrument delivered to, and reasonably satisfactory
to, the holder of this Warrant, (x) the obligations of the Company under this
Warrant (and if the Company shall survive the consummation of any such
transaction, such assumption shall be in addition to, and shall not release the
Company from, any continuing obligations of the Company under this Warrant) and
(y) the obligation to deliver to such holder such cash, stock, securities or
other assets as such holder may be entitled to receive in accordance with the
provisions of this Section 3. The provisions of this Section 3.6 shall similarly
apply to successive transactions.

4. Issue Tax. The issuance of certificates for shares of Common Stock upon the
exercise of this Warrant shall be made without charge to the holder for any
issue tax in respect thereon provided, however, that the Company shall not be
required to pay any tax which may be payable in respect of any transfer involved
in the issuance and delivery of any certificate in a name other than that of the
then holder of the Warrant being exercised.

5. No Voting Rights Limitation of Liability. Nothing contained in this Warrant
shall be construed as conferring upon Holder the right to vote or to consent


<PAGE>   7


or to receive notice as a stockholder in respect of meetings of stockholders for
the election of directors of the Company or any other matters or any rights
whatsoever as a stockholder of the Company. No provisions hereof, in the absence
of affirmative action by Holder to purchase shares of Common Stock, and no mere
enumeration herein of the rights or privileges of Holder, shall give rise to any
liability of Holder for the Stock Purchase Price or as a stockholder of the
Company whether such liability is asserted by the Company or by its creditors.


6. Restrictions on Transferability of Securities: Compliance With Securities
Act.

6.1 Restrictions on Transferability. This Warrant and the Warrant Shares
(collectively, the "Securities"), shall not be transferable in the absence of
registration under the Act or an exemption therefrom under such Act.

6.2 Restrictive Legend. Each certificate representing the Securities or any
other securities issued in respect of the Securities upon any stock split, stock
dividend, recapitalization, merger, consolidation or similar event, shall
(unless otherwise permitted by the provisions of the Shareholders Agreement) be
stamped or otherwise imprinted with a legend substantially in the following form
(in addition to any legend required under applicable state securities laws):

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED ("ACT"), OR ANY STATE SECURITIES LAWS AND NEITHER SUCH
SECURITIES NOR ANY INTEREST THEREIN MAY BE TRANSFERRED IN THE ABSENCE OF SUCH
REGISTRATION OR AN EXEMPTION THEREFROM UNDER SUCH ACT AND SUCH LAWS AND THE
RULES AND REGULATIONS THEREUNDER.

6.3 Effect of Transfer. Subject to the provisions of Section 6.1 hereof, Holder
may transfer all or any portion of this Warrant by surrendering this Warrant to
the Company together with a completed assignment in the form attached hereto as
Exhibit B. Upon such surrender, the Company shall deliver a new Warrant or
Warrants to the person or persons entitled thereto and, if applicable, shall
deliver to Holder a new Warrant evidencing the right of Holder to purchase the
balance of the Warrant Shares subject to purchase hereunder. The term "Holder"
as used herein shall include any transferee to whom this Warrant has been
transferred in accordance with this Section 6.3.

6.4 Registration. The Company will use its reasonable best efforts, upon the
written request of the Holder, to register, as promptly as practicable, the
shares of Common Stock received by the Holder upon exercise of this Warrant.

7. Modification and Waiver. This Warrant and any provision hereof may be
changed, waived, discharged or terminated only by an instrument in writing
signed by the party against which enforcement of the same is sought.

8. Notices. Any notice, request or other document required or permitted to be
given or delivered to Holder or the Company shall be personally delivered, sent
by telecopier (receipt confirmed), sent by recognized overnight delivery service
or sent by certified or registered mail, postage prepaid, to Holder at its
address as shown on the books of the Company or to the Company at the address
indicated therefor in the first paragraph of this Warrant. Any notice given by
personal delivery or by telecopier shall be deemed given on the date of
delivery, any notice sent by recognized overnight courier service shall be
deemed delivered on the second following business day, and any notice given by
certified or registered mail shall be deemed given five days after registration
or certification thereof, as the case may be.


<PAGE>   8


9. Descriptive Headings. Governing Law and Jurisdiction. The descriptive
headings of the several sections and paragraphs of this Warrant are inserted for
convenience only and do not constitute a part of this Warrant. This Warrant
shall be construed and enforced in accordance with, and the rights of the
parties shall be governed by, the laws of the State of Delaware, without giving
effect to rules governing conflicts of law. Any judicial proceeding involving
any dispute, controversy or claim arising out of or relating to this Warrant may
be brought in a court located in the Lubbock, Texas, and each of the Company and
Holder (i) unconditionally accepts the non-exclusive jurisdiction of such courts
and any related appellate court and irrevocably agrees to be bound by any
judgment rendered thereby, (ii) irrevocably waives any objection it may now or
hereafter have as to the venue of any such proceeding brought in such a court or
that such a court is an inconvenient forum and (iii) waives personal service of
any and all process upon it, and consents that all such service of process be
made by registered or certified mail, return receipt requested, directed to it
at its address set forth in the Purchase Agreement. Each of the Company and
Holder hereby waives trial by jury in any judicial proceeding to which it is a
party.

10. Lost Warrants or Stock Certificates. The Company represents and warrants to,
and agrees with, Holder that upon receipt of evidence reasonably satisfactory to
the Company of the loss, theft, destruction, or mutilation of any Warrant or
stock certificate and, in the case of any such loss, theft or destruction, upon
receipt of an indemnity, or in the case of any such mutilation, upon surrender
and cancellation of such Warrant or stock certificate, the Company at its
expense will make and deliver a new Warrant or stock certificate, of like
tenor, in lieu of the lost, stolen, destroyed or mutilated Warrant or stock
certificate.

11. Fractional Shares. No fractional shares shall be issued upon exercise of
this Warrant. The Company shall, in lieu of issuing any fractional share, pay
Holder a sum in cash equal to such fraction multiplied by the fair market value
of the Common Stock.

         IN WITNESS WHEREOF, the Company has caused this Warrant to be executed
by a duly authorized officer this 4th day of March, 1998.

Norton Drilling Services, Inc.

By:  /s/  DAVID W. RIDLEY
   -----------------------------------
      Treasurer


<PAGE>   9
                                   EXHIBIT A

                           FORM OF STOCK SUBSCRIPTION

(To be signed only upon exercise of Warrant)

To:  UTI ENERGY CORPORATION
   ------------------------

The undersigned, the holder of the accompanying Warrant, hereby irrevocably
elects, to exercise the purchase right represented by such Warrant for, and to
purchase thereunder, Six Thousand Four Hundred (6,400) shares of Common Stock
(the "Common Stock"), of Norton Drilling Services Inc. (the "Company") and
herewith makes payment of Twenty Thousand Dollars and No Cents ($20,000.00)
therefore by official bank check and requests that certificates for Three
Thousand Three Hundred Sixty-eight (3,368) shares of Common Stock of UTI Energy
Corp. be issued in the name of, and delivered to, The Norton Family Trust, whose
address is 5211 Brownfield Highway, Suite 230, Lubbock, TX 79407.

         The undersigned represents, unless the sale of the Common Stock has
been registered under the Securities Act of 1933, as amended (the "Securities
Act"), that the undersigned is acquiring such Common Stock for its own account
for investment and not with a view to or for sale in connection with any
distribution thereof (except for any resale pursuant to a Registration Statement
under the Securities Act).


DATED:    October 21, 2000

                                     /s/ S. HOWARD NORTON, III
                                    -------------------------------------------
                                                S. Howard Norton, III
                                                      Trustee


                                     /s/ BARBARA LYNN NORTON
                                    -------------------------------------------
                                                Barbara Lynn Norton
                                                      Trustee


                                     /s/ JOHN W. NORTON
                                    -------------------------------------------
                                                 John W. Norton
                                                      Trustee

Address:                            5211 Brownfield Highway, Suite 230
                                    Lubbock, TX 79407-3501