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Exhibit 4.20  

  
 

    IRREVOCABLE CONVERSION NOTICE AND AGREEMENT    
    

	To:
	Pioneer
Drilling Company ("Pioneer")

9310 Broadway, Building I

San Antonio, Texas 78217 

        The
undersigned registered holder of an original aggregate principal amount of $27,000,000 of Pioneer's 6.75% Convertible Subordinated Debentures due July 3, 2007, (the
"Debentures"), hereby exercises its option to convert the Debentures into 6,264,501 shares of common stock of Pioneer in accordance with the terms of the Debenture Agreement by and between WEDGE
Energy Services, L.L.C. ("WEDGE") and Pioneer dated as of July 3, 2002, as amended (the "Debenture Agreement"), effective immediately prior to the closing of the Offering (defined below) and
subject to the provisions of the last two paragraphs hereof, and directs that the shares issuable and deliverable upon such conversion, together with any check for cash deliverable upon such
conversion, be issued and delivered to WEDGE at the following address: 

WEDGE
Energy Services, L.L.C.

1415 Louisiana, Suite 3000

Houston, Texas 77002 

        This
notice shall be deemed to be an irrevocable exercise of the option to convert the Debentures immediately prior to the closing of the Offering (the "Effective Time"); provided that,
this notice shall become revocable upon written notice to Pioneer if the closing of the Offering has not occurred prior to December 31, 2004. WEDGE covenants and agrees to deliver the
Debentures to Pioneer within 5 days of the date of this notice. Pioneer covenants and agrees that after such time as Pioneer has received the Debentures and until the earlier of (i) the
Effective Time or (ii) such time as WEDGE is entitled to revoke and does revoke this notice pursuant to the first sentence of this paragraph, Pioneer shall hold the Debentures in escrow, after
which, in the case of a revocation, Pioneer shall return the Debentures to WEDGE upon WEDGE's written request. Unless notice has been earlier revoked
pursuant to the first sentence of this paragraph, at the Effective Time, the Debentures will be converted into 6,264,501 shares of Pioneer common stock. 

        For
purposes of this notice, the term "Offering" shall mean the offering which is contemplated to be made by Pioneer and certain selling shareholders, including WEDGE, pursuant to a
registration statement on Form S-1 with the U.S. Securities and Exchange Commission to be initially filed in the quarter ending September 30, 2004 and pursuant to which
Pioneer is proposing to offer up to 4,600,000 shares of its common stock in a public offering and certain selling shareholders, including WEDGE, are also proposing to offer up to 5,269,320 shares of
Pioneer's common stock which they hold. This notice shall not affect Pioneer's right to redeem the Debentures in accordance with the terms of the Debenture Agreement and the parties hereto agree that,
notwithstanding any provision in the Debenture Agreement to the contrary regarding the effective date of the conversion, this notice shall constitute a valid 

exercise
of WEDGE's conversion rights under the Debenture Agreement effective as of the Effective Time. 

	

July 9, 2004	

WEDGE Energy Services, L.L.C.
	

 	

By:	

/s/  RICK E. BLOHM      

	 	Title:	Vice President

Accepted and Agreed to July 9, 2004: 

	

/s/  WM. STACY LOCKE      
 Wm. Stacy Locke

President and Chief Executive Officer

Pioneer Drilling Company	
 	

 

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IRREVOCABLE CONVERSION NOTICE AND AGREEMENT$0.75 warrant form

	Unless permitted under securities legislation,
        the holder of the securities shall not trade the securities before June
        1, 2004.

 

	 Without prior written approval of the TSX Venture
        Exchange and compliance with all applicable securities legislation, the
        securities represented by this certificate may not be sold, transferred,
        hypothecated or otherwise traded on or through the facilities of the TSX
        Venture Exchange or otherwise in Canada or to or for the benefit of a
        Canadian resident until June 1, 2004. 

 WARRANT TO PURCHASE COMMON STOCK

  OF 

 U.S. GEOTHERMAL INC.

  (formerly U.S. Cobalt Inc.) 

 Warrant Certificate No: •

      THIS WARRANT AND THE SECURITIES
  TO BE ISSUED UPON ITS EXERCISE HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
  ACT OF 1933 OR UNDER APPLICABLE STATE SECURITIES LAWS. THE WARRANT REPRESENTED
  HEREBY MAY NOT BE EXERCISED BY OR ON BEHALF OF ANY U.S. PERSON UNLESS
  REGISTERED UNDER THE SECURITIES ACT OF 1933 AND ANY APPLICABLE STATE SECURITIES
  LAWS, OR AN EXEMPTION FROM SUCH REGISTRATION IS AVAILABLE. EACH PERSON
  EXERCISING THE WARRANT REPRESENTED BY THIS CERTIFICATE SHALL BE REQUIRED TO
  GIVE A WRITTEN CERTIFICATION THAT IT IS NOT A U.S. PERSON AND THE WARRANT
  IS NOT BEING EXERCISED ON BEHALF OF A U.S. PERSON, OR AN OPINION OF COUNSEL,
  ACCEPTABLE TO THE COMPANY, TO THE EFFECT THAT THE WARRANT REPRESENTED HEREBY
  AND THE SECURITIES DELIVERABLE UPON EXERCISE HEREOF HAVE BEEN REGISTERED
  UNDER THE SECURITIES ACT OF 1933 AND UNDER APPLICABLE STATE SECURITIES LAWS
  OR ARE EXEMPT FROM REGISTRATION THEREUNDER. HEDGING TRANSACTIONS INVOLVING THIS
  WARRANT AND THE UNDERLYING COMMON STOCK MAY NOT BE CONDUCTED UNLESS IN
  COMPLIANCE WITH THE SECURITIES ACT OF 1933. 

FOR VALUE RECEIVED 

 U.S. Geothermal Inc., a Delaware corporation (the "Company"), grants the following
  rights to •., having an address at • ("Holder"). 

ARTICLE 1. DEFINITIONS 

As used herein, the following terms shall have the following meanings, unless the context shall otherwise require: 

	 	 (a)      	 "Call Event" shall mean that the Company
        (or a subsidiary thereof) has obtained a license from the applicable permitting
        authorities for a 10 megawatt power plant, including a power purchase
        agreement and transmission agreement. 

	 
	 	 (b)      	 "Common Stock" shall mean the common stock,
        $.001 par value per share, of the Company. 

	 

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	 	 (c)      	 "Corporate Office" shall mean the office
        of the Company (or its successor) at which at any particular time its
        principal business shall be administered, which office is located at the
        date hereof at 1509 Tyrell Lane, Suite B, Boise, Idaho 83706.

	 	 	

	 	 (d)      	 "Exercise Date" shall mean any date upon
        which the Holder shall give the Company a Notice of Exercise, which shall
        be deemed the date the Notice of Exercise was first deposited in the US
        Mails, if mailed, or the date received by the courier company if delivered
        by recognized courier company, or the date received by the Company if
        otherwise given or delivered. 

	 
	 	 (e)      	 "Exercise Price" shall mean the price to
        be paid to the Company for each whole share of Common Stock to be purchased
        upon exercise of this Warrant in accordance with the terms hereof, which
        shall be • per share. 

	 
	 	 (f)      	 "Expiration Date" shall mean the first to
        occur of (i) 5:00 PM (Pacific time) on December 19, 2005 or (ii) the end
        of the period of Notice set forth in Section 2.2 if sooner called pursuant
        to Article 2. 

	 
	 	 (g)      	 "SEC" shall mean the United States Securities
        and Exchange Commission. 

ARTICLE 2. EXERCISE

	 2.1      	 Exercise of Warrant 
	 
	 	 This Warrant shall entitle Holder to purchase
        up to • shares of Common Stock (the "Shares") at the Exercise Price.
        This Warrant shall be exercisable at any time and from time to time prior
        to the Expiration Date (the "Exercise Period"). This Warrant and the right
        to purchase Shares hereunder shall expire and become void at the Expiration
        Date. This Warrant may be exercised for whole Shares only. 

	 
	 2.2      	 Acceleration of Exercise Period
      

	 
	 	 The Company shall have the right, at any
        time after the occurrence of a Call Event, to accelerate the Exercise
        Period by sending to the Holder, at the Holder's address written above,
        a Notice of Acceleration in substantially the form attached as Appendix
        I hereto (the "Notice"). In the event the Company does accelerate the
        Exercise Period, Holder shall have until 5:00 p.m. (Pacific time) on the
        date which is thirty (30) days from the date the Holder is deemed to receive
        the Notice within which to exercise this Warrant in the manner provided
        for in Section 2.3. If this Warrant is not exercised within said period,
        thereafter this Warrant and the right to purchase the Shares hereunder,
        to the extent not previously exercised, shall expire and become void.
      

	 
	 2.3      	 Manner of Exercise 

	 
	 	 (a)      	 Holder may exercise this Warrant at any time and
        from time to time during the Exercise Period, in whole or in part by delivering
        to the Company at its Corporate Office (i) a duly executed Notice of Exercise
        in substantially the form attached as Appendix II hereto and (ii) a bank
        cashier's or certified check for the aggregate Exercise Price of the Shares
        being purchased. 

	 
	 	 (b)      	 From time to time upon exercise of this Warrant,
        in whole or part, in accordance with its terms, the Company will cause
        its transfer agent to countersign and deliver stock certificates to the
        Holder representing the number of Shares being purchased pursuant to such
        exercise, subject to adjustment as described herein. 

	 

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	 	 (c)      	 Promptly following any exercise of this Warrant,
        if the Warrant has not been fully exercised and has not expired, the Company
        will deliver to the Holder a new Warrant for the balance of the Shares
        covered hereby. 

	 

	 2.4      	 Termination 
	 
	 	 All rights of the Holder in this Warrant, to the extent they have not
      previously expired or been exercised, shall terminate on the Expiration
      Date. 
	 
	 2.5      	 No Rights Prior to Exercise 
	 
	 	 Prior to its exercise pursuant to Section 2.3 above, this Warrant shall
      not entitle the Holder to any voting or other rights as holder of Shares.
    
	 
	 2.6      	 Adjustments 
	 
	 	 In case of any reclassification, capital reorganization, stock dividend,
      or other change of outstanding shares of Common Stock, or in case of any
      consolidation or merger of the Company with or into another corporation
      (other than a consolidation or merger in which the Company is the continuing
      corporation and which does not result in any reclassification, capital reorganization,
      stock dividend, or other change of outstanding shares of Common Stock),
      or in case of any sale or conveyance to another corporation of the property
      of the Company as, or substantially as, an entirety (other than a sale/leaseback,
      mortgage or other financing transaction), the Company shall cause effective
      provision to be made so that the Holder shall have the right thereafter,
      by exercising this Warrant, to purchase the kind and number of shares of
      stock or other securities or property (including cash) receivable upon such
      reclassification, capital reorganization, stock dividend, or other change,
      consolidation, merger, sale or conveyance as the Holder would have been
      entitled to receive had the Holder exercised this Warrant in full immediately
      before such reclassification, capital reorganization, stock dividend, or
      other change, consolidation, merger, sale or conveyance. Any such provision
      shall include provision for adjustments that shall be as nearly equivalent
      as may be practicable to the adjustments provided for in this Section 2.6.
      The foregoing provisions shall similarly apply to successive reclassifications,
      capital reorganizations, stock dividends, and other changes of outstanding
      shares of Common Stock and to successive consolidations, mergers, sales
      or conveyances. The Company shall have the exclusive authority to make all
      such adjustments. 
	 
	 2.7      	 Fractional Shares 
	 
	 	 No fractional Shares shall be issuable upon exercise or conversion of
      this Warrant and the number of Shares to be issued shall be rounded down
      to the nearest whole Share. If a fractional Share interest arises upon any
      exercise or conversion of the Warrant, the Company shall eliminate such
      fractional Share interest by paying Holder the amount computed by multiplying
      the fractional interest by the closing bid price of a full Share on the
      date of the Notice of Exercise. 

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY

	 3.1      	 Representations and Warranties 
	 
	 	 The Company hereby represents and warrants to the Holder as
      follows: 
	 
	 	 (a)      	 All Shares which may be issued upon the exercise
        of the purchase right represented by this Warrant shall, upon issuance,
        by duly authorized, validly issued, fully-paid and non- assessable, and
        free of any liens and encumbrances except for restrictions on transfer
        provided for herein or under applicable securities laws, and not subject
        to any pre-emptive rights. 

	 
	 	 (b)      	 The Company is a corporation duly organized and
        validly existing under the laws of the State of Delaware and has the full
        power and authority to issue this Warrant and to comply 

	 

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	 	 	 with the terms hereof. The execution, delivery and
        performance by the Company of its obligations under this Warrant, including,
        without limitation, the issuance of the Shares upon any exercise of the
        Warrant, have been duly authorized by all necessary corporate action.
        This Warrant has been duly executed and delivered by the Company and is
        a valid and binding obligation of the Company, enforceable in accordance
        with its terms, except as enforcement may be limited by applicable bankruptcy,
        insolvency, reorganization or similar laws affecting enforceability of
        creditors' rights generally and except as the availability of the remedy
        of specific enforcement, injunctive relief or other equitable relief is
        subject to the discretion of the court before which any proceeding therefor
        may be brought. 

	 	 	 
	 	 (c)      	 The Company is not subject to or bound by any provision
        of any certificate or articles of incorporation or by-laws, mortgage,
        deed of trust, lease, note, bond, indenture, other instrument or agreement,
        license, permit, trust, custodianship, other restriction or any applicable
        provision of any law, statute, any court, governmental body, administrative
        agency or arbitrator which could prevent or be violated by or under which
        there would be a default (or right of termination) as a result of the
        execution, delivery and performance by the Company of this Warrant. 

ARTICLE 4. MISCELLANEOUS

	 4.1      	 Restrictions on Transfer 
	 
	 	 This Warrant may not be transferred or assigned,
        in whole or in part, at any time. 

	 
	 4.2      	 Loss, Theft, Destruction or Mutilation 
	 
	 	 If this Warrant shall become mutilated or defaced
        or be destroyed, lost or stolen, the Company shall execute and deliver
        a new Warrant in exchange for and upon surrender and cancellation of such
        mutilated or defaced Warrant or, in lieu of and in substitution for such
        Warrants so destroyed, lost or stolen, upon the Holder filing with the
        Company evidence satisfactory to it that such Warrant has been so mutilated,
        defaced, destroyed, lost or stolen. However, the Company shall be entitled,
        as a condition to the execution and delivery of such new Warrant, to demand
        indemnity satisfactory to it and payment of the expenses and charges incurred
        in connection with the delivery of such new Warrant. Any Warrant so surrendered
        to the Company shall be cancelled. 

	 
	 4.3      	 Notices 

	 
	 	 All notices and other communications from the Company
        to the Holder or vice versa shall be deemed delivered and effective when
        given personally (including by recognized courier delivery), by facsimile
        transmission and confirmed in writing, or three (3) days after being mailed
        by first- class United States Postal Service mail, postage prepaid, at
        such address and/or facsimile number as may have been furnished to the
        Company or the Holder, as the case may be, in writing by the Company or
        the Holder from time to time; provided, however, that the Notice of Exercise
        may not be delivered by facsimile transmission. 

	 
	 4.4      	 Waiver 

	 
	 	 This Warrant and any term hereof may be changed,
        waived, or terminated only by an instrument in writing signed by the party
        against which enforcement of such change, waiver, discharge or termination
        is sought. 

	 
	 4.5      	 Governing Law 

	 
	 	 This Warrant shall be governed by and construed
        in accordance with the laws of the State of Delaware, without
        giving effect to its principles regarding conflicts of law. 

	 

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4.6      		
Restrictions on Shares	
	 
	 	 This Warrant and any Shares issuable on its exercise
        are subject to resale restrictions under applicable securities laws. If
        the Shares underlying the Warrants are not the subject of an effective
        registration statement under the Act upon issuance by the Company, legends
        stating that such Shares have not been registered and referring to restrictions
        on transferability and sale of the Shares may be placed upon all certificates
        or other documents evidencing ownership, and stop- order instructions
        prohibiting transfer of the Shares or similar notations may be made on
        the Company's records to prevent the disposition of Shares other than
        in accordance with applicable law. 

	 

 Dated: •

	 	 U.S. Geothermal Inc., a Delaware corporation 
    
	 	  
	 	  
	 	  
	 	 By:  __________________________
	 	         Paul Larkin, Director 
    

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APPENDIX I 

NOTICE OF ACCELERATION 

 Dated: ___________________

 U.S. Geothermal Inc. (the "Company") does hereby notify you of its election
  to exercise its right, pursuant to Section 2.2 of the Warrant issued to you
  by the Company on _________________

   (the "Warrant"), to accelerate the exercise period of
such Warrant with respect to all unexercised Shares for which the Warrant may be exercised. Please be advised that you have thirty (30) days from the date you are deemed to receive this Notice of Acceleration (the "Notice Period") to exercise your
Warrant in the manner provided for in the Warrant. You will be deemed to have received this Notice of Acceleration three (3) days after the date when this Notice of Acceleration was first deposited in the United States mail, if mailed, or upon
receipt if delivered personally or by facsimile. 

 You will automatically forfeit your right to purchase any shares of common
  stock issuable upon exercise of such Warrant, unless the Warrant is exercised
  with respect to such Shares before the end of the Notice Period.  

	 	 U.S. Geothermal Inc., a Delaware corporation 
	 	 
	 	 By:  _______________________
	 	 Name:  _____________________
	 	 Title:  ______________________

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APPENDIX II 

NOTICE OF EXERCISE

	 1.      	 The undersigned hereby elects to purchase ________ shares of the Common
      Stock of U.S. 
	 
	 	 Geothermal Inc. pursuant to the terms of the attached Warrant, and tenders
      herewith payment of the purchase price of such shares in full. 
	 
	 2.      	 Please issue a certificate or certificates representing said shares and
      reissue a Warrant for the balance of the shares remaining in the name of
      the undersigned holder as specified below. 
	 
	 3.      	 The undersigned represents it is acquiring the shares solely for its
      own account and not as a nominee for any other party and not with a view
      toward the resale or distribution thereof except in compliance with applicable
      securities laws. 
	 
	 	 Holder: ________________________________ 

 

	___________________________	___________________________
	 (Signature)  	 (Date)  
	 	 
	 	 
	 Address:  ___________________________	  
	                  ___________________________

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