Document:

Exhibit 4.2

Exhibit 4.2

REGISTRATION RIGHTS AGREEMENT

This Registration Rights Agreement dated as of June 26, 2009 (this “Agreement”), is
made and entered into by and between Allis-Chalmers Energy Inc., a Delaware corporation (the
“Company”) and Lime Rock Partners V, L.P., a Cayman Islands exempted limited partnership
(the “Investor”).

WHEREAS, this Agreement is being entered into pursuant to the Investment Agreement dated as of
May 20, 2009 (the “Investment Agreement”) at the Backstop Closing (as defined in the
Investment Agreement) at which the Investor is purchasing, and the Company is issuing and selling,
certain shares of the common stock, par value $0.01 per share, of the Company (the “Common
Stock”);

WHEREAS, in connection with its obligations under the Investment Agreement, the Company may
sell to the Investor shares of the Company’s 7.0% Convertible Perpetual Preferred Stock (the
“Preferred Stock”) on the terms and subject to the conditions set forth therein and in any
Certificate Of Designation governing the terms of the Preferred Stock filed with the Delaware
Secretary of State; and

WHEREAS, in connection with its purchase of shares of Common Stock and Preferred Stock
pursuant to the Investment Agreement, the Investor wishes to receive certain registration rights
related to its Common Stock (including Common Stock issuable upon conversion of the Preferred
Stock), and the Company desires to grant such rights on the terms and subject to the conditions set
forth herein;

NOW, THEREFORE, in consideration of the foregoing and other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree as
follows:

Section 1. Definitions. As used herein, the following terms have the indicated
meanings, unless the context otherwise requires:

“Agreement” has the meaning given to such term in the preamble hereto.

“Beneficially Own,” “Beneficially Owned,” “Beneficial Ownership” and
“Beneficial Owner” with respect to any securities means a Holder having such ownership,
control or power to direct the voting with respect to, or which otherwise enables a Holder to
legally act with respect to, such securities as contemplated hereby, including without limitation
pursuant to any agreement, arrangement or understanding, regardless of whether in writing.
Securities “Beneficially Owned” shall include securities Beneficially Owned by all other
persons with whom a Holder would constitute a “group” as within the meaning of Section 13(d) of the
Exchange Act.

“Blackout Period” means, with respect to a Registration Statement, a period in each
case commencing on the day immediately after the Company notifies the Holders pursuant to Section
3(e) that they are required to suspend offers and sales of Registrable Securities because the
Company, in the good faith judgment of the Board, determines that the registration and distribution
of (and/or the registration of the offer and sale of) the Registrable Securities covered or to be
covered by such Registration Statement would (a) materially interfere with a significant
acquisition, financing activity, or other transaction involving the Company or (b) require
premature disclosure of financial statements or information which it is in the Company’s best
interest not to publicly disclose at the time and ending on the earlier of (x) the date upon which
the material non-public information to which the Blackout Period relates is disclosed to the public
or ceases to be material and (y) such time as the Company notifies the selling Holders that the
Company will no longer delay such filing of such Registration Statement, recommence taking steps to
make such Registration Statement effective, or allow sales pursuant to such Registration Statement
to resume; provided that no Blackout Period may last for more than 90 consecutive days; and
provided, further, that during any period of 365 consecutive days, Blackout Periods may not, in the
aggregate, last for more than the result of 120 days minus the number of days that Holders were
previously required pursuant to Section 3(e) to discontinue and suspend disposition of Registrable
Securities because of the happening of any event described in Section 3(d)(vi).

 

 

 

“Board” means the board of directors of the Company.

“Business Day” means any day of the year, other than a Saturday, Sunday, or other day
on which the SEC is required or authorized to close.

“Common Stock” has the meaning given to such term in the recitals hereto.

“Company” has the meaning given to such term in the preamble hereto.

“Effectiveness Period” has the meaning given to such term in Section 3(d)(i).

“Equity Securities Offering” means any underwritten registered offering of Relevant
Securities, and any offering or placement of any Relevant Securities pursuant to Rule 144A under
the Securities Act.

“Exchange Act” means the Securities Exchange Act of 1934, as amended, and the rules
and regulations of the SEC promulgated thereunder.

“Family Member” means (a) with respect to any individual, such individual’s spouse,
any descendants (whether natural or adopted), any trust all of the beneficial interests of which
are owned by any of such individuals or by any of such individuals together with any organization
described in Section 501(c)(3) of the Internal Revenue Code of 1986, as amended, the estate of any
such individual, and any corporation, association, partnership, limited liability company or other
entity all of the equity interests of which are owned by those above described individuals, trusts
or organizations and (b) with respect to any trust, the owners of the beneficial interests of such
trust.

“FINRA” means the Financial Industry Regulatory Authority.

“Form S-1” means such form under the Securities Act as in effect on the date of this
Agreement or any successor registration form thereto under the Securities Act subsequently adopted
by the SEC.

 

2

 

“Form S-3” means such form under the Securities Act as in effect on the date of this
Agreement or any successor registration form thereto under the Securities Act subsequently adopted
by the SEC.

“Form S-4” means such form under the Securities Act as in effect on the date of this
Agreement or any successor registration form thereto under the Securities Act subsequently adopted
by the SEC.

“Form S-8” means such form under the Securities Act as in effect on the date of this
Agreement or any successor registration form thereto under the Securities Act subsequently adopted
by the SEC.

“Holder” means the Investor or any of the Investor’s successors and Permitted
Assignees who acquire rights in accordance with this Agreement with respect to the Registrable
Securities directly or indirectly from the Investor or another Holder (including from any Permitted
Assignee) and “Holders” means all of the foregoing individuals or entities.

“Inspector” means any attorney, accountant or other agent retained by a Holder or any
underwriter for the purposes provided in Section 3(d)(x).

“Investment Agreement” has the meaning given to such term in the recitals hereto.

“Investor” has the meaning given to such term in the preamble hereto.

“Market Standoff Period” means, with respect to each Equity Securities Offering, the
period beginning on the date of first sale of securities pursuant to such Equity Securities
Offering and ending on the date that shall be requested by the Company or the underwriters or
initial purchasers retained by the Company to facilitate such Equity Securities Offering; provided,
however, that each such period shall not be more than 120 days; and provided further that (a) such
period shall be no longer than the shortest period imposed by the Company or the underwriters or
initial purchasers upon any other person or entity (including any lockup period imposed upon the
Company) and (b) if any other person or entity receives a waiver with respect to any such matters,
the Holders shall be given a waiver with respect to their Relevant Securities as well.

“Permitted Assignee” means (a) with respect to a partnership or limited partnership,
its partners or former partners in accordance with their partnership interests, (b) with respect to
a corporation, its stockholders or former stockholders in accordance with their interest in the
corporation, (c) with respect to a limited liability company, its members or former members in
accordance with their interest in the limited liability company, (d) with respect to an individual,
any Family Member, (e) an entity that is controlled by, controls, or is under common control with a
transferor or (f) the transferee in any transfer not prohibited pursuant to Section 8.4 of the
Investment Agreement.

“Piggyback Offering” has the meaning given to such term in Section 3(b)(i).

“Piggyback Registration Statement” has the meaning given to such term in Section
3(b)(i).

 

3

 

“Piggyback Supplement” has the meaning given to such term in Section 3(b)(i).

“Preferred Stock” has the meaning given to such term in the recitals hereto.

“register,” “registered,” and “registration” refer to a registration
effected by preparing and filing a registration statement in compliance with the Securities Act,
and the declaration or ordering of the effectiveness, or automatic effectiveness, of such
registration statement.

“Registrable Securities” means (a) the shares of Common Stock acquired by the Investor
pursuant to the Backstop Commitment, as defined in the Investment Agreement, (b) the shares of
Common Stock received by the Investor upon conversion of any Preferred Stock acquired by the
Investor pursuant to the Investment Agreement, (c) any and all shares of capital stock or other
equity securities of the Company which are added to or exchanged or substituted for such shares of
Common Stock by reason of the declaration of any stock dividend or stock split, the issuance of any
distribution or the reclassification, readjustment, recapitalization or other such modification of
the capital structure of the Company and (d) any and all shares of capital stock or other equity
securities of any other corporation (now or hereafter organized under the laws of any state or
other governmental authority) with which the Company is merged, which results from any
consolidation or reorganization to which the Company is a party, or to which is sold all or
substantially all of the shares or assets of the Company, for which such shares of Common Stock are
exchanged or substituted in connection with such merger, consolidation, reorganization or sale, if
immediately after such merger, consolidation, reorganization or sale, the Company or the
stockholders of the Company own equity securities having in the aggregate more than 50% of the
total voting power of such other corporation. As to any particular Registrable Securities, such
securities shall cease to be Registrable Securities when (w) a Registration Statement with respect
to the sale of such securities shall have become effective under the Securities Act and such
securities shall have been sold, transferred, disposed of or exchanged in accordance with such
Registration Statement, (x) such securities shall have been otherwise transferred (other than to a
Permitted Assignee who becomes a Holder in accordance with this Agreement), new certificates for
such securities that do not bear a legend restricting further transfer shall have been delivered by
the Company and subsequent public distribution of them shall not require Registration under the
Securities Act, (y) such securities shall have ceased to be outstanding, or (z) such securities are
sold under Rule 144.

“Registration Expenses” has the meaning given to such term in Section 3(f).

“Registration Statement” means any Piggyback Registration Statement, the Shelf
Registration Statement and, if offers of Registrable Securities are included in any other
registration statement filed by the Company by means of a Piggyback Supplement, such other
registration statement, and “Registration Statements” means all such registration
statements collectively.

“Relevant Security” means the Shares, any other equity security of the Company or any
of its subsidiaries and any security convertible into, or exercisable or exchangeable for, any
Shares or other such equity security.

“SEC” means the Securities and Exchange Commission or any other federal agency at the
time administering the Securities Act.

 

4

 

“SEC Effective Date” means, with respect to a Registration Statement, the date as of
which such Registration Statement is originally declared effective by the SEC or otherwise becomes
effective in accordance with the Securities Act.

“Securities Act” means the Securities Act of 1933, as amended, or any similar federal
statute promulgated in replacement thereof, and the rules and regulations of the SEC thereunder,
all as the same shall be in effect from time to time.

“Selling Expenses” has the meaning given to such term in Section 3(f).

“Shares” means the shares of Common Stock originally issued and sold to the Investor
pursuant to the Investment Agreement and the shares of Common Stock received by a Holder upon
conversion of any Preferred Stock acquired by the Investor pursuant to the Investment Agreement and
(a) any and all shares of capital stock or other equity securities of the Company which are added
to or exchanged or substituted for such shares of Common Stock by reason of the declaration of any
stock dividend or stock split, the issuance of any distribution or the reclassification,
readjustment, recapitalization or other such modification of the capital structure of the Company;
and (b) any and all shares of capital stock or other equity securities of any other corporation
(now or hereafter organized under the laws of any state or other governmental authority) with which
the Company is merged, which results from any consolidation or reorganization to which the Company
is a party, or to which is sold all or substantially all of the shares or assets of the Company,
for which such shares of Common Stock are exchanged or substituted in connection with such merger,
consolidation, reorganization or sale.

“Shelf Registration Statement” has the meaning given to such term in Section 3(a).

“Transfer” has the meaning given to such term in Section 2(a).

Section 2. Market Standoff. Notwithstanding anything to the contrary set forth in
this Agreement, with respect to each Equity Securities Offering conducted after the date hereof,
the following provisions of this Section 2 shall apply, if and only if (x) the underwriters or
initial purchasers retained by the Company to facilitate such offering request, in connection with
such offering, that the officers or directors or significant stockholders of the Company refrain
from selling any Relevant Security during any period, and (y) either (1) any Investor Director (as
defined in the Investment Agreement) is a member of the Board, or (2) the Holders Beneficially Own
shares of Common Stock representing at least 5% of the fully diluted equity interests in the
Company (calculated giving effect to the conversion of all shares of Preferred Stock and the
exercise of all outstanding options, warrants and other rights to purchase or acquire any Common
Stock of the Company):

(a) Following notice of the applicability of this Section 2, during the Market Standoff Period
applicable to such Equity Securities Offering, each Holder will not, without the prior written
consent of the Company, (i) directly or indirectly offer, sell, agree to offer or sell, solicit
offers to purchase, grant any call option or purchase any put option with respect to, pledge,
borrow or otherwise dispose of any Relevant Security, or (ii) establish or increase any “put
equivalent position” or liquidate or decrease any “call equivalent position” (in each case within
the meaning of Section 16 of the Exchange Act) with respect to any Relevant Security, or otherwise
enter into any swap, derivative or other transaction or arrangement that transfers to another, in
whole or in part, any economic consequence of ownership of a Relevant Security
(each of the transactions described in the immediately preceding clauses (i) and (ii), being
referred to as a “Transfer”), regardless of whether such transaction is to be settled by
delivery of Relevant Securities, other securities, cash or other consideration; provided, however,
that a Transfer to a Permitted Assignee will not be subject to this Section 2 as long as (1) such
Transfer is effected in accordance with applicable securities laws, (2) the transferee in such
Transfer agrees in writing to become subject to the terms of this Agreement as a Holder and (3) the
Company is given written notice by such Holder of such Transfer, stating the name and address of
the transferee and identifying the Relevant Securities being transferred; and provided, further,
that this Section 2(a) will not prohibit transfers of Relevant Securities included in such Equity
Securities Offering.

 

5

 

(b) Furthermore, each Holder hereby authorizes the Company during the Market Standoff Period
to cause any transfer agent for the Relevant Securities to decline to transfer, and to note stop
transfer restrictions on the stock register and other records relating to, any Relevant Securities
for which such Holder is the record holder and, in the case of Relevant Securities for which such
Holder is the Beneficial Owner but not the record holder, agrees during the Market Standoff Period
to cause the record holder thereof to cause the relevant transfer agent to decline to transfer, and
to note stop transfer restrictions on the stock register and other records relating to, such
Relevant Securities.

(c) Subject to the provisions of Section 3(b), without the prior written consent of the
Company, during the Market Standoff Period such Holder (i) will not participate in the filing with
the SEC of any registration statement, or circulate or participate in the circulation of any
preliminary or final prospectus or other disclosure document with respect to any proposed offering
or sale of a Relevant Security and (ii) will not exercise any rights the undersigned may have to
require registration with the SEC of any proposed offering or sale of a Relevant Security
(including without limitation pursuant to this Agreement).

Section 3. Registration Rights.

(a) Shelf Registration Statement. The Company shall (i) file with the SEC a shelf
registration statement on Form S-1 (or, if the Company is eligible to use such form, Form S-3)
relating to the registration of the offer and resale by the Holders of all of the Registrable
Securities (the “Shelf Registration Statement”) and (ii) use its commercially reasonable
efforts to cause the Shelf Registration Statement to be declared effective by the SEC no later than
the date that is one (1) year after the date hereof; provided, however, that the Company shall not
be obligated to effect any such registration pursuant to this Section 3(a), or keep such
registration or the Shelf Registration Statement effective pursuant to Section 3(d)(i), during any
Blackout Period.

(b) Piggyback Registration Rights.

(i) Piggyback Registration. If after the date that is one (1) year after the
date hereof, the Company shall determine to (A) file a registration statement to register
the offer and sale for cash of any of its Common Stock for its own account in an
underwritten offering, other than (i) a registration relating solely to employee benefit
plans or securities issued or issuable to employees, directors or consultants (to the extent
the securities owned or to be owned by such consultants could be registered on Form S-8) or
any of their Family Members (including a registration on Form S-8), (ii) a registration on
Form S-4 in connection with a merger, acquisition, divestiture, reorganization,
exchange offer or similar event, (iii) a registration in which the only Common Stock being
registered is Common Stock issuable upon conversion of debt securities that are also being
registered or (iv) a shelf registration statement on Form S-3 or (B) file a prospectus
supplement to an effective shelf registration statement with respect to an underwritten
public offering in which Holders may be included (either by inclusion in the registration
statement without the filing of a post-effective amendment thereto or because the Shelf
Registration Statement is effective) (an offering pursuant to clause (A) or (B), a
“Piggyback Offering”), then the Company shall promptly give to the Holders written
notice thereof, and in no event shall such notice be given less than (X) twenty (20)
calendar days prior to the filing of a registration statement contemplated by clause (A) (a
“Piggyback Registration Statement”) or (Y) five (5) calendar days prior to the
filing of a prospectus supplement contemplated by clause (B) ( a “Piggyback
Supplement”) and the Company shall, subject to Section 3(b)(ii), include in such
Piggyback Offering all of the Registrable Securities specified in a written request or
requests, made within ten (10) calendar days (three (3) calendar days in the case of a
Piggyback Supplement) after receipt of such written notice from the Company, by any Holder
or Holders. However, the Company may, without the consent of the Holders, abandon such
Piggyback Offering and withdraw such Piggyback Registration Statement or Piggyback
Supplement.

 

6

 

(ii) Underwriting Procedures. The right of any Holder to be included in a
Piggyback Offering pursuant to Section 3(b)(i) shall be conditioned upon such Holder’s
participation in, and the inclusion of such Holder’s Registrable Securities in, the
underwriting arrangements with respect to such Piggyback Offering to the extent provided
herein. All Holders proposing to sell their securities through such Piggyback Offering
shall (together with the Company) enter into an underwriting agreement in customary form
with the underwriter or underwriters selected for such Piggyback Offering by the Company.
No Holder may participate in such Piggyback Offering unless such Holder agrees to sell its
Registrable Securities on the basis provided in such underwriting agreement and completes
and executes all questionnaires, powers of attorney, indemnities and other documents
reasonably required under the terms of such underwriting agreement. Each Holder may, at its
option, require that any or all of the representations and warranties by, and the other
agreements on the part of, the Company to and for the benefit of the underwriters also be
made to and for such Holder’s benefit and that any or all of the conditions precedent to the
obligations of the underwriters under such underwriting agreement also be conditions
precedent to such Holder’s obligations. No Holder shall be required to make any
representations or warranties to or agreements with the Company or the underwriters other
than representations, warranties or agreements regarding such Holder and its ownership of
the securities being registered on its behalf, its intended method of distribution and any
other representation required by law, and no Holder shall be required to agree to indemnify
any person beyond the scope of the indemnification provided to the Company under Section
3(h). Notwithstanding any other provision of this Section 3(b)(ii), if the managing
underwriter or the Company determines that marketing factors require a limitation of the
number of shares to be underwritten, the underwriters may exclude from such Piggyback
Offering the number of shares in excess of such limitation. The Company shall so advise all
Holders (except those Holders who failed to timely elect to sell their Registrable
Securities through such
Piggyback Offering or have indicated to the Company their decision not to do so), and
the number of shares that may be included in the underwriting shall be allocated:

(A) first, to the Company;

(B) second, to the Holders who have requested to sell their Registrable
Securities in the Piggyback Offering and all other selling stockholders who have
rights of registration on parity with the Holders and have requested to sell
securities in the Piggyback Offering, on a pro rata basis according to the number of
 shares requested to be included; and

 

7

 

(C) then, to any other selling stockholders who have registration rights and
have requested to sell securities in the Piggyback Offering.

No Registrable Securities excluded from the underwriting by reason of the underwriters’
marketing limitation shall be included in the Piggyback Offering. If any Holder disapproves
of the terms of the underwriting arrangements with respect to a Piggyback Offering, such
Holder may elect to withdraw therefrom by written notice to the Company and the managing
underwriter; provided, however, that such withdrawal must be made at a time prior to the
time of the pricing of the Piggyback Offering. The Registrable Securities and/or other
securities so withdrawn from such underwriting shall also be withdrawn from such Piggyback
Offering; provided, however, that, if by the withdrawal of such Registrable Securities a
greater number of Registrable Securities held by other Holders may be included in such
Piggyback Offering (up to the maximum of any limitation imposed by the underwriters), then
the Company shall offer to all Holders who have included Registrable Securities in the
Piggyback Offering the right to include additional Registrable Securities pursuant to the
terms and limitations set forth herein in the same proportions described above.

(c) Requested Underwritings.

(i) In the event that one or more Holders elects to sell $25 million or more of
Registrable Securities under the Shelf Registration Statement, the Company shall, upon
request by such Holders, retain underwriters in order to permit such Holders to effect such
offering. The obligation of the Company to retain underwriters shall include entering into
an underwriting agreement in customary form with the underwriters or initial purchasers,
which shall include, among other provisions, indemnities to the effect and to the extent
provided in Section 3(h) and taking all reasonable actions as are requested by the
underwriters or initial purchaser to expedite or facilitate the disposition of such
Registrable Securities. The Company shall, upon request of the Holders, cause its
management to participate in a roadshow or similar marketing effort on behalf of the
Holders.

(ii) In no event shall the Company be required to participate in more than two
underwritten offerings in any 12-month period.

 

8

 

(iii) In connection with any underwritten offering pursuant to this Section 3(c), (A)
Holders holding a majority of the Registrable Securities being sold in such underwritten
offering shall be entitled to select the managing underwriter or initial
purchaser, subject to the approval of the Company, which approval shall not be
unreasonably withheld and (B) each Holder participating in the underwritten offering and the
Company shall be obligated to enter into an underwriting agreement in customary form. No
Holder may participate in such underwritten offering unless such Holder agrees to sell its
Registrable Securities on the basis provided in such underwriting agreement and completes
and executes all questionnaires, powers of attorney, indemnities and other documents
reasonably required under the terms of such underwriting agreement. Each Holder may, at its
option, require that any or all of the representations and warranties by, and the other
agreements on the part of, the Company to and for the benefit of the underwriters also be
made to and for such Holder’s benefit and that any or all of the conditions precedent to the
obligations of the underwriters under such underwriting agreement also be conditions
precedent to such Holder’s obligations. No Holder shall be required to make any
representations or warranties to or agreements with the Company or the underwriters other
than representations, warranties or agreements regarding such Holder and its ownership of
the securities being registered on its behalf, its intended method of distribution and any
other representation required by law, and no Holder shall be required to agree to indemnify
any person beyond the scope of the indemnification provided to the Company under Section
3(h). If any Holder disapproves of the terms of the underwriting arrangements with respect
to such underwritten offering, such Holder may elect to withdraw therefrom by written notice
to the Company and the underwriter; provided, however, that such withdrawal must be made at
a time prior to the time of pricing of such underwritten offering. Neither the Company nor
any selling stockholders who have registration rights shall have any right to include
securities in an underwritten offering by the Holders pursuant to this Section 3(c) and the
Company shall not purport to grant any current or future shareholder such right.

(d) Registration Procedures. In the case of each registration, offering,
qualification, or compliance effected by the Company pursuant to Section 3(a), Section 3(b) or
Section 3(c), the Company will keep each Holder including securities therein reasonably advised in
writing (which may include e-mail) as to the initiation of each registration, offering,
qualification, and compliance and as to the completion thereof. In addition, the Company hereby
agrees as follows:

(i) The Company will use its commercially reasonable efforts to cause the Shelf
Registration Statement to become and remain effective at least for a period ending with the
first to occur of (A) the sale by the Holders of all Registrable Securities covered by such
Registration Statement, (B) the sale of such Registrable Securities under Rule 144, or (C)
the date that is three years after the SEC Effective Date of the Shelf Registration
Statement; provided, however, that if the Company files the Shelf Registration Statement on
Form S-1, subsequently becomes eligible to use Form S-3, and files a post-effective
amendment to such Form S-1 on Form S-3 prior to the end of such period, the Company will use
its commercially reasonable efforts to cause such Shelf Registration Statement as amended to
remain effective until the end of such period (in any such case, the “Effectiveness
Period”). At any time after the end of the Effectiveness Period with respect to the
Shelf Registration Statement, if (a) the Holders Beneficially Own Registrable Securities
representing more than 5% of the fully diluted equity interests in the Company (calculated
giving effect to the exercise of all outstanding options, warrants and other rights to
purchase or acquire any Common Stock of the
Company) or (b) any Investor Director (as defined in the Investment Agreement) is a
member of the Board, then (w) as promptly as reasonably practicable after the written
request of Holders of a majority of the Registrable Securities, the Company shall file with
the SEC another shelf registration statement on Form S-1 (or, if the Company is eligible to
use such form, Form S-3) relating to the registration of the offer and resale by the Holders
of all of the Registrable Securities, (x) the provisions of this Agreement (including
without limitation the provisions of Section 3(a) and Section 3(d)) shall apply to such
registration statement, (y) such registration statement shall be deemed to be the Shelf
Registration Statement (as defined in Section 3(a)) for purposes of this Agreement and (z)
the Effectiveness Period shall resume upon effectiveness of any such shelf registration
statement for the period specified in the first sentence of this Section 3(d)(i).

 

9

 

(ii) If any Registration Statement becomes subject to review by the SEC, the Company
will promptly respond to all comments and diligently pursue resolution of any comments to
the satisfaction of the SEC.

(iii) The Company (A) will prepare and file with the SEC such amendments and
supplements to each Shelf Registration Statement and any prospectus used in connection
therewith as may be reasonably necessary to keep such Shelf Registration Statement effective
during the applicable Effectiveness Period, (B) will comply with the provisions of the
Securities Act with respect to the disposition of all securities covered by such Shelf
Registration Statement during such period in accordance with the intended method(s) of
disposition by the sellers thereof set forth in such Shelf Registration Statement and (C),
if advised in writing by the managing underwriter of an underwritten offering that, in the
judgment of such underwriter, inclusion of detailed information regarding the Company in the
prospectus or prospectus supplement is of material importance to the success of such
offering, will use its commercially reasonable efforts to include such information in such
prospectus or prospectus supplement.

(iv) The Company will furnish, without charge, to each Holder (A) a reasonable number
of copies of each Registration Statement (including any exhibits thereto other than exhibits
incorporated by reference), each amendment and supplement thereto as such Holder may
request, (B) such number of copies of the prospectus included in such Registration Statement
(including each preliminary prospectus and any other prospectus filed under Rule 424 under
the Securities Act) as each Holder may request, in conformity with the requirements of the
Securities Act, and (C) such other documents as each Holder may reasonably request in order
to facilitate the disposition of the Registrable Securities owned by such Holder, but only
during the applicable Effectiveness Period.

(v) The Company will use its commercially reasonable efforts to register or qualify the
Registrable Securities under the applicable securities or blue sky laws of such
jurisdictions as the Holders of a majority of the Registrable Securities reasonably requests
as may be necessary for the marketability of the Registrable Securities (such request to be
made by the time the relevant Registration Statement is deemed effective by the SEC) and do
any and all other acts and things which may be reasonably necessary or advisable to enable
the Holders to consummate the disposition in such jurisdictions of the Registrable
Securities owned by the Holders; provided, however, that the Company shall
not be required to (A) qualify generally to do business in any jurisdiction where it
would not otherwise be required to qualify but for this paragraph (v), (B) subject itself to
taxation in any such jurisdiction, or (C) consent to general service of process in any such
jurisdiction.

 

10

 

(vi) As promptly as practicable after becoming aware of such event, the Company will
notify each Holder of Registrable Securities being offered or sold pursuant to each
Registration Statement at any time when a prospectus relating thereto is required to be
delivered under the Securities Act of the happening of any event which comes to the
Company’s attention if as a result of such event the prospectus included in such
Registration Statement contains an untrue statement of a material fact or omits to state any
material fact required to be stated therein or necessary to make the statements therein not
misleading, and the Company shall promptly prepare and furnish to such Holder a supplement
or amendment to such prospectus (or prepare and file appropriate reports under the Exchange
Act) so that, as thereafter delivered to the purchasers of such Registrable Securities, such
prospectus shall not contain an untrue statement of a material fact or omit to state any
material fact required to be stated therein or necessary to make the statements therein not
misleading, unless suspension of the use of such prospectus otherwise is authorized herein
or in the event of a Blackout Period, in which case no supplement or amendment need be
furnished (or Exchange Act filing made) until the termination of such suspension or Blackout
Period.

(vii) The Company will comply, and continue to comply during the period that each
Registration Statement is effective under the Securities Act, in all material respects with
the Securities Act and the Exchange Act and with all applicable rules and regulations of the
SEC with respect to the disposition of all securities covered by such Registration
Statement.

(viii) As promptly as practicable after becoming aware of such event, the Company will
notify each Holder of Registrable Securities being offered or sold pursuant to each
Registration Statement of the issuance by the SEC of any stop order or other suspension of
effectiveness of such Registration Statement.

(ix) The Company will permit the Holders of Registrable Securities being offered or
sold pursuant to each Registration Statement and their legal counsel, at such Holders’ sole
cost and expense, to review and have a reasonable opportunity to comment on such
Registration Statement and all amendments and supplements thereto (unless such Registration
Statement, amendments and supplements are filed without inclusion of any Registrable
Securities therein) at least two (2) Business Days prior to their filing with the SEC, and
will make any corrections reasonably requested by any such Holder with respect to
information pertaining to such Holder and its plan of distribution prior to such filing.

 

11

 

(x) The Company will make available for inspection by the Holders and any Inspector
retained by the Holders, at the Holders’ sole expense, all records as shall be reasonably
necessary to enable the Holders and any underwriters to exercise their due diligence
responsibility, and cause the Company’s officers, directors, and employees to supply all
information which the Holders, any Inspector or any underwriter may
reasonably request for purposes of such due diligence; provided, however, that the
Holders shall hold in confidence and shall not make any disclosure of any information which
the Company determines in good faith to be confidential, and of which determination the
Holders are so notified at the time the Holders receive such information, unless (A) the
Holders have, or obtained, knowledge of such information without violation of or protection
under any agreements with the Company or, to its knowledge any third party, (B) the
disclosure of such information is reasonably necessary to avoid or correct a misstatement or
omission in each Registration Statement and a reasonable time prior to such disclosure the
Holders shall have informed the Company of the need to so correct such misstatement or
omission and the Company shall have failed to correct such misstatement of omission, (C) the
release of such information is ordered pursuant to a subpoena or other order from a court or
governmental body of competent jurisdiction or (D) the information has been made generally
available to the public other than by disclosure in violation of this Agreement or any other
agreement. The Company shall not be required to disclose any confidential information to
any Holder, Inspector or underwriter until and unless such Holder, Inspector or underwriter
shall have entered into a confidentiality agreement with the Company with respect thereto,
containing terms substantially similar to those set forth in this Section 3(d)(x), which
agreement shall permit an Inspector retained by any Holder to disclose information to such
Holder. Each Holder agrees that it shall, upon learning that disclosure of such information
is sought in or by a court or governmental body of competent jurisdiction or through other
means, give prompt notice to the Company and allow the Company, at the Company’s expense, to
undertake appropriate action to prevent disclosure of, or to obtain a protective order for,
the information deemed confidential. The Company shall hold in confidence and shall not
make any disclosure of information concerning the Holders provided to the Company pursuant
to this Agreement unless (1) disclosure of such information is reasonably necessary to
comply with federal or state securities laws, (2) disclosure of such information to the
SEC’s Staff of the Division of Corporation Finance is reasonably necessary to respond to
comments raised by such staff in its review of such Registration Statement, (3) disclosure
of such information is reasonably necessary to avoid or correct a misstatement or omission
in such Registration Statement, (4) release of such information is ordered pursuant to a
subpoena or other order from a court or governmental body of competent jurisdiction, or (5)
such information has been made generally available to the public other than by disclosure in
violation of this or any other agreement. The Company agrees that it shall, upon learning
that disclosure of such information concerning the Holders is sought in or by a court or
governmental body of competent jurisdiction or through other means, give prompt notice to
the Holders and allow the Holders, at the Holders’ expense, to undertake appropriate action
to prevent disclosure of, or to obtain a protective order for, such information.

(xi) The Company will use its commercially reasonable efforts to cause all the
Registrable Securities covered by each Registration Statement to be listed or quoted on the
principal securities market on which securities of the same class or series issued by the
Company are then listed or traded.

(xii) The Company will provide a transfer agent and registrar, which may be a single
entity, for the Registrable Securities at all times.

 

12

 

(xiii) The Company will cooperate with the Holders of Registrable Securities being
offered pursuant to each Registration Statement to facilitate the timely preparation and
delivery of certificates (not bearing any restrictive legends) representing Registrable
Securities to be offered pursuant to such Registration Statement and enable such
certificates to be in such denominations or amounts as the Holders may reasonably request.

(xiv) The Company will take all other reasonable actions necessary to expedite and
facilitate disposition by the Holders of the Registrable Securities pursuant to each
Registration Statement, including without limitation making its chief executive officer,
president, chief financial officer and other appropriate officers and personnel available to
participate in marketing efforts with respect to any registered underwritten public
offering.

(xv) In the case of an underwritten offering, the Company shall furnish to the
participating Holders signed counterparts, addressed to such Holders, of (i) any opinion of
counsel to the Company delivered to any underwriter and (ii) any comfort letter from the
Company’s independent public accountants (or accountants for any entity acquired by the
Company whose financial statements are included in a Registration Statement) delivered to
any underwriter.  In the event no legal opinion is delivered to any underwriter, or in
non-underwritten transactions, the Company shall furnish to participating Holders, at any
time that such Holders elect to use a prospectus, an opinion of counsel to the Company
stating only that the Registration Statement containing such prospectus has been declared
effective and that no stop order is in effect.

(xvi) The Company shall comply with all applicable rules and regulations of the SEC and
the Securities Act, and also make available to its stockholders, as soon as practicable, an
earnings statement covering a period of twelve (12) months, beginning within three
(3) months after the effective date of the Registration Statement, which earnings statement
shall satisfy the provisions of Section 11(a) of the Securities Act and Rule 158 thereunder.

(e) Suspension of Offers and Sales. Each Holder of Registrable Securities agrees
that, upon receipt of any notice from the Company of the happening of any event of the kind
described in Section 3(d)(vi) or of the commencement of a Blackout Period, such Holder shall
discontinue and suspend disposition of Registrable Securities pursuant to any Registration
Statement until the Holder’s receipt of the copies of the supplemented or amended prospectus
contemplated by Section 3(d)(vi) or notice of the end of the Blackout Period, and, if so directed
by the Company, such Holder shall deliver to the Company (at the Company’s expense) all copies
(including, without limitation, any and all drafts), other than permanent file copies, then in such
Holder’s possession, of the prospectus covering such Registrable Securities current at the time of
receipt of such notice.

(f) Registration Expenses. All expenses incident to the Company’s performance of or
compliance with this Agreement, including without limitation all registration and filing fees,
messenger and delivery expenses, printing expenses, internal expenses (including without limitation
all salaries and expenses of its officers and employees performing legal or accounting duties), all
fees and expenses associated with filings required to be made with FINRA, as may be
required by the rules and regulations of FINRA, fees and expenses of compliance with
securities or blue sky laws (including reasonable fees and disbursements of counsel in connection
with blue sky qualifications of the Registrable Securities), rating agency fees, the fees and
expenses incurred in connection with the listing of the securities to be registered on all
securities exchanges on which similar securities issued by the Company are then quoted or listed,
fees and disbursements of counsel for the Company and its independent certified public accountants,
and the fees and expenses of any other persons retained by the Company, in connection with the
registration hereunder (collectively, the “Registration Expenses”) will be borne by the
Company, but not including any roadshow expenses of the Holders, fees and expenses of counsel for
the Holders and any underwriting, broker or dealer discounts or commissions attributable to the
sale of Registrable Securities (which are hereinafter referred to as “Selling Expenses”).
All Selling Expenses shall be borne solely by the Holders.

 

13

 

(g) Information by the Holder. The Holder or Holders of Registrable Securities
included in any Registration Statement shall furnish to the Company such information required under
Regulation S-K under the Securities Act regarding such Holder or Holders and the distribution
proposed by such Holder or Holders as the Company may request in writing. No Holder of Registrable
Securities will be entitled to have such Registrable Securities included in a Registration
Statement if such Holder does not furnish such information requested by the Company.

(h) Indemnification.

(i) In the event of the offer and sale of Registrable Securities under the Securities
Act, the Company shall, and hereby does, indemnify and hold harmless, to the fullest extent
permitted by law, each Holder, its directors, officers, employees, agents, and partners,
each other person who participates as an underwriter in the offering or sale of such
securities, and each other person, if any, who controls or is under common control with such
Holder or any such underwriter within the meaning of Section 15 of the Securities Act,
against any losses, claims, damages, liabilities (joint or several), and expenses to which
such Holder or any such director, officer, employee, agent or partner, underwriter or
controlling person may become subject under the Securities Act or otherwise, insofar as such
losses, claims, damages, liabilities or expenses (or actions or proceedings, whether
commenced or threatened, in respect thereof) arise out of or are based upon any untrue
statement or alleged untrue statement of any material fact contained in (A) any Registration
Statement, any preliminary prospectus, final prospectus, summary prospectus or free writing
prospectus, or any amendment or supplement thereto, or (B) in any materials or information
provided to investors by, or with the written approval of, the Company in connection with
the marketing of the offering of the Registrable Securities (“Marketing Materials”),
including any road show or investor presentations made to investors by the Company (whether
in person or electronically), or any omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements therein (in
the case of any prospectus or free writing prospectus, in light of the circumstances in
which they were made) not misleading, and the Company shall reimburse the Holder, and each
such director, officer, employee, agent, partner, underwriter and controlling person for any
legal or any other expenses reasonably incurred by them in connection with investigating,
defending or settling any such loss, claim, damage, liability, action or proceeding;
provided that the foregoing shall not apply, and the Company shall not be liable, in
any such case to the extent that any such loss, claim, damage, liability (or action or
proceeding, whether commenced or threatened, in respect thereof) or expense arises out of or
is based upon (X) an untrue statement or alleged untrue statement in or omission or alleged
omission from such Registration Statement, any such preliminary prospectus, final
prospectus, summary prospectus or free writing prospectus, or any such amendment or
supplement in reliance upon and in conformity with written information furnished to the
Company through an instrument duly executed by or on behalf of such Holder specifically
stating that it is for use in the preparation thereof, or (Y) such Holder’s failure to
comply with the terms of the plan of distribution mechanics described in the applicable
prospectus. Such indemnity shall remain in full force and effect regardless of any
investigation made by or on behalf of the Holders, or any such director, officer, employee,
agent, partner, underwriter or controlling person, and shall survive the transfer of such
 shares by the Holders.

 

14

 

(ii) As a condition to including any Registrable Securities to be offered by a Holder
in any Registration Statement, such Holder agrees to be bound by the terms of this Section
3(h) and to indemnify and hold harmless, to the fullest extent permitted by law, the
Company, its directors, officers, employees and agents, each other person, if any, who
controls the Company within the meaning of Section 15 of the Securities Act, legal counsel
and accountants for the Company, any underwriter, any other Holder selling securities in
such Registration Statement (or any other registration statement filed by the Company to
which a Piggyback Supplement relates) and any controlling person within the meaning of the
Securities Act of any such underwriter or other Holder, against any losses, claims, damages,
liabilities (joint or several), and expenses to which the Company, any of its directors,
officer, employees, agents, controlling persons, legal counsel or accountants, any
underwriter, any other Holder, or any controlling person of such underwriter or other Holder
may become subject under the Securities Act or otherwise, insofar as such losses, claims,
damages, liabilities (or actions or proceedings, whether commenced or threatened, in respect
thereof) or expenses arise out of or are based upon (A) an untrue statement or alleged
untrue statement in or omission or alleged omission from any Registration Statement (or any
other registration statement filed by the Company to which a Piggyback Supplement relates),
any preliminary prospectus, final prospectus, summary prospectus or free writing prospectus,
or any amendment or supplement thereto, if such statement or alleged statement or omission
or alleged omission was made in reliance upon and in conformity with written information
furnished to the Company through an instrument duly executed by or on behalf of such Holder
specifically stating that it is for use in the preparation thereof, or (B) such Holder’s
failure to comply with the terms of the plan of distribution mechanics described in the
applicable prospectus. Such indemnity shall remain in full force and effect regardless of
any investigation made by or on behalf of the Company, any such director, officer, employee,
agent or controlling person, any such underwriter or other Holder, or any controlling person
of any such underwriter or other Holder, and shall survive the transfer of such shares by
the Holder, and such Holder shall reimburse the Company, any of its directors, officer,
employees, agents, controlling persons, legal counsel or accountants, any underwriter, any
other Holder, or any controlling person of such underwriter or other Holder for any legal or
other expenses reasonably incurred by them in connection with investigating, defending, or
settling such loss, claim, damage, liability,
action, or proceeding; provided, however, that such indemnity agreement found in this
Section 3(h)(ii) shall in no event exceed the gross proceeds from the offering received by
such Holder.

 

15

 

(iii) Promptly after receipt by an indemnified party of notice of the commencement of
any action or proceeding involving a claim referred to in Section 3(h)(i) or Section
3(h)(ii) (including any governmental action), such indemnified party shall, if a claim in
respect thereof is to be made against an indemnifying party, give written notice to the
indemnifying party of the commencement of such action; provided, however, that the failure
of any indemnified party to give notice as provided herein shall not relieve the
indemnifying party of its obligations under Section 3(h)(i) or Section 3(h)(ii), except to
the extent that the indemnifying party is actually prejudiced by such failure to give
notice. If any such action is brought against an indemnified party, unless in the
reasonable judgment of counsel to such indemnified party a conflict of interest between such
indemnified and indemnifying parties may exist (including situations in which the
indemnified party may have defenses not available to the indemnifying party) in respect of
such claim, the indemnifying party shall be entitled to participate in and to assume the
defense thereof, with counsel reasonably satisfactory to such indemnified party and, after
notice from the indemnifying party to such indemnified party of its election so to assume
the defense thereof, the indemnifying party shall not be liable to such indemnified party
for any legal or other expenses subsequently incurred by the latter in connection with the
defense thereof, unless in such indemnified party’s reasonable judgment a conflict of
interest between such indemnified and indemnifying parties arises in respect of such claim
after the assumption of the defenses thereof or the indemnifying party fails to defend such
claim in a diligent manner, other than reasonable costs of investigation. Neither an
indemnified nor an indemnifying party shall be liable for any settlement of any action or
proceeding effected without its consent. No indemnifying party shall, without the consent
of the indemnified party, consent to entry of any judgment or enter into any settlement,
which does not include as an unconditional term thereof the giving by the claimant or
plaintiff to such indemnified party of a release from all liability in respect of such claim
or litigation. Notwithstanding anything to the contrary set forth herein, and without
limiting any of the rights set forth above, in any event any party shall have the right to
retain, at its own expense, counsel with respect to the defense of a claim.

(iv) In the event that an indemnifying party does or is not permitted to assume the
defense of an action pursuant to Section 3(h)(iii) or in the case of the expense
reimbursement obligation set forth in Section 3(h)(i) and Section 3(h)(ii), the
indemnification required by Section 3(h)(i) and Section 3(h)(ii) shall be made by periodic
payments of the amount thereof during the course of the investigation or defense, as and
when bills received or expenses, losses, damages, or liabilities are incurred.

 

16

 

(v) If the indemnification provided for in this Section 3(h) is held by a court of
competent jurisdiction to be unavailable to an indemnified party with respect to any loss,
liability, claim, damage or expense referred to herein, the indemnifying party, in lieu of
indemnifying such indemnified party hereunder, shall (A) contribute to the amount paid or
payable by such indemnified party as a result of such loss, liability, claim, damage or
expense as is appropriate to reflect the proportionate relative fault of the
indemnifying party on the one hand and the indemnified party on the other (determined
by reference to, among other things, whether the untrue or alleged untrue statement of a
material fact or omission relates to information supplied by the indemnifying party or the
indemnified party and the parties’ relative intent, knowledge, access to information and
opportunity to correct or prevent such untrue statement or omission), or (B) if the
allocation provided by clause (A) above is not permitted by applicable law or provides a
lesser sum to the indemnified party than the amount hereinafter calculated, not only the
proportionate relative fault of the indemnifying party and the indemnified party, but also
the relative benefits received by the indemnifying party on the one hand and the indemnified
party on the other, as well as any other relevant equitable considerations; provided,
however, that in no event shall any Holder be required to contribute an aggregate amount in
excess of the gross proceeds from the offering received by such Holder. No indemnified
party guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the
Securities Act) shall be entitled to contribution from any indemnifying party who was not
guilty of such fraudulent misrepresentation.

(vi) Indemnification similar to that specified in the preceding subsections of this
Section 3(h) (with appropriate modifications) shall be given by the Company and each Holder
of Registrable Securities with respect to any required registration or other qualification
of securities under any federal or state law or regulation or governmental authority other
than the Securities Act.

Section 4. Miscellaneous.

(a) Assignment of Rights; Successors and Permitted Assignees. No Holder may assign
its rights under this Agreement to any party without the prior written consent of the Company;
provided, however, that a Holder may assign its rights under this Agreement without such
restrictions to a Permitted Assignee as long as (i) such transfer or assignment is effected in
accordance with applicable securities laws; (ii) such transferee or assignee agrees in writing to
become subject to the terms of this Agreement as a Holder; and (iii) the Company is given written
notice by such Holder of such transfer or assignment, stating the name and address of the
transferee or assignee and identifying the Registrable Securities with respect to which such rights
are being transferred or assigned. Except as otherwise provided herein, the provisions of this
Agreement shall inure to the benefit of, and be binding upon, the successors, Permitted Assignees,
heirs, legatees, executors and administrators of the parties hereto.

 

17

 

(b) Notices. All notices or other communications which are required or permitted
under this Agreement shall be in writing and sufficient if delivered by hand, by facsimile
transmission, by registered or certified mail, postage pre-paid, by electronic mail, or by courier
or overnight carrier, to the persons at the addresses set forth below (or at such other address as
may be provided hereunder), and shall be deemed to have been delivered as of the date so delivered:

	 	 	 	 	 
	 

	 	If to the Company:
	 	Allis-Chalmers Energy Inc.
	 

	 	 	 	5075 Westheimer, Suite 890
	 

	 	 	 	Houston, Texas 77056
	 

	 	 	 	Attention: General Counsel
	 

	 	 	 	Facsimile: (713) 369-0555
	 
	 	 	 	 
	 

	 	with a copy (which shall not

constitute notice) to:
	 	Andrews Kurth LLP

600 Travis, Suite 4200
	 

	 	 	 	Houston, Texas 77002
	 

	 	 	 	Attention: Henry Havre
	 

	 	 	 	Facsimile: (713) 238-7279
	 
	 	 	 	 
	 

	 	If to the Investor:
	 	Lime Rock Partners V, L.P.
	 

	 	 	 	274 Riverside Ave.
	 

	 	 	 	Westport, CT 06880
	 

	 	 	 	Attention: Saad Bargach
	 

	 	 	 	Kris Agarwal

	 

	 	 	 	Facsimile: (203) 429-2785
	 
	 	 	 	 
	 

	 	with a copy (which shall not

constitute notice) to:
	 	Vinson & Elkins L.L.P.

666 Fifth Avenue, 26th Floor
	 

	 	 	 	New York, NY 10103
	 

	 	 	 	Attention: Caroline Blitzer
	 

	 	 	 	Facsimile: (917) 849-5317
	 
	 	 	 	 
	 

	 	If to a Holder other than the
Investor:
	 	to such address specified in the notice
required by Section 4(a)

or at such other address as any party shall have furnished to the other party in writing.

(c) Limitation on Subsequent Registration Rights. From and after the date hereof, the
Company shall not, without the prior written consent of the Holders of a majority of the
outstanding Registrable Securities, enter into any agreement with any current or future holder of
any securities of the Company that would allow such current or future holder to require the Company
to include securities in any registration statement filed by the Company or underwritten offering
on a basis that is on a parity with or superior in any way to the registration rights granted to
the Holders hereunder.

(d) Rule 144. The Company covenants that it shall file any reports required to be
filed by it under the Securities Act and the Exchange Act and shall take such further action as the
Holders may reasonably request, all to the extent required from time to time to enable the Holders
to sell Registrable Securities without registration under the Securities Act within the
limitations of the exemption provided by Rule 144 under the Securities Act, as such rule may
be amended from time to time, or any similar rule or regulation hereafter adopted by the SEC.

 

18

 

(e) Specific Performance. Each party to this Agreement agrees that any breach by it
of any provision of this Agreement would irreparably injure the other party and that money damages
would be an inadequate remedy therefor. Accordingly, each party agrees that the other party shall
be entitled to one or more injunctions enjoining any such breach and requiring specific performance
of this Agreement and consents to the entry thereof, in addition to any other remedy to which such
other party is entitled at law or in equity.

(f) Counterparts. This Agreement may be executed in any number of counterparts, each
of which shall be enforceable against the parties actually executing such counterparts, and all of
which together shall constitute one instrument.

(g) Amendments. The provisions of this Agreement may be amended at any time and from
time to time, and particular provisions of this Agreement may be waived, with and only with an
agreement or consent in writing signed by the Company and by the Holders of a majority of the
Registrable Securities outstanding as of the date of such amendment or waiver. The Investor
acknowledges that by the operation of this Section 4(g), the Holders of a majority of the
outstanding Registrable Securities may have the right and power to diminish or eliminate all rights
of the Holders under this Agreement.

(h) Obligations Limited to Parties to Agreement. Each of the parties hereto
covenants, agrees and acknowledges that no person other than the Company and the Holders shall have
any obligation hereunder and that, notwithstanding that one or more of the Holders may be a
corporation, partnership or limited liability company, no recourse under this Agreement or under
any documents or instruments delivered in connection herewith shall be had against any former,
current or future director, officer, employee, agent, general or limited partner, manager, member,
stockholder or affiliate of any of the Holders or any former, current or future director, officer,
employee, agent, general or limited partner, manager, member, stockholder or affiliate of any of
the foregoing, whether by the enforcement of any assessment or by any legal or equitable
proceeding, or by virtue of any applicable law, it being expressly agreed and acknowledged that no
personal liability whatsoever shall attach to, be imposed on or otherwise by incurred by any
former, current or future director, officer, employee, agent, general or limited partner, manager,
member, stockholder or affiliate of any of the Holders or any former, current or future director,
officer, employee, agent, general or limited partner, manager, member, stockholder or affiliate of
any of the foregoing, as such, for any obligations of the Holders under this Agreement or any
documents or instruments delivered in connection herewith or for any claim based on, in respect of
or by reason of such obligation or its creation, except in each case for any assignee of a Holder
hereunder.

 

19

 

(i) Headings and Cross References. The headings of the several sections and
subsections of this Agreement are inserted for convenience only and shall not in any way affect the
meaning or construction of any provision of this Agreement. Unless the context requires otherwise,
all cross references in this Agreement refer to sections and subsections of this Agreement.

(j) Severability. In the case any provision of this Agreement shall be invalid,
illegal or unenforceable, the validity, legality and enforceability of the remaining provisions
shall not in any way be affected or impaired thereby.

(k) Entire Agreement. This Agreement constitutes the full and entire understanding
and agreement between the parties with regard to the subject matter of this Agreement.

(l) Governing Law. This Agreement shall be governed by and construed in accordance
with the laws of the State of New York.

(Remainder of Page Intentionally Left Blank)

 

20

 

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed as of
the date first above written.

	 	 	 	 	 	 	 	 	 
	 	 	THE COMPANY:	 	 
	 	 	 	 	 
	 
	 	 	 	 	 	 	 	 
	 	 	ALLIS-CHALMERS ENERGY INC.	 	 
	 
	 	 	 	 	 	 	 	 
	 	 	By:	 	/s/ Victor M. Perez	 	 
	 	 	 	 	 	 	 
	 

	 	 	 	Name:
	 	Victor M. Perez	 	 
	 

	 	 	 	Title:
	 	Chief Financial Officer	 	 
	 
	 	 	 	 	 	 	 	 
	 	 	INVESTOR:	 	 
	 	 	 	 	 
	 
	 	 	 	 	 	 	 	 
	 	 	LIME ROCK PARTNERS V, L.P.	 	 
	 
	 	 	 	 	 	 	 	 
	 	 	By:	 	Lime Rock Partners GP V, L.P., its general partner	 	 
	 
	 	 	 	 	 	 	 	 
	 	 	By:	 	LRP GP V, Inc., its general partner	 	 
	 
	 	 	 	 	 	 	 	 
	 	 	By:	 	/s/ Saad Bargach	 	 
	 	 	 	 	 	 	 
	 

	 	 	 	Name:
	 	Saad Bargach	 	 
	 

	 	 	 	Title:
	 	Authorized Person	 	 

Registration Rights Agreement Signature Pageexv10w1

Exhibit 10.1

FIRST AMENDMENT TO

EXECUTIVE EMPLOYMENT AGREEMENT

     WHEREAS, Nabors Industries Ltd. and Nabors Industries, Inc. (collectively, “the Company”) and
Eugene M. Isenberg (“Employee”), entered into an Executive Employment Agreement (the “Agreement”)
effective as of April 1, 2009; and

     WHEREAS, in consideration of the current economic conditions and in lieu of other cost
reductions, Employee and the Company desire to decrease temporarily the compensation payable to
Employee under the Agreement;

     NOW, THEREFORE, for and in consideration of the mutual promises, covenants and obligations
contained herein, the Company and Employee agree to amend the Agreement as follows, effective June
29, 2009:

	 	1.	 	Section 3.1(a) of the Agreement is amended by adding after the first sentence:
“However, on an interim basis commencing June 29, 2009 and ending on December 27, 2009
the amount of base salary due and payable for purposes of biweekly payroll
administration only shall be based on an annual salary of One Million One Hundred
Seventy Thousand Dollars ($1,170,000). For all other purposes under this Agreement,
the term “Base Salary” or “base salary” shall be construed in accordance with the first
sentence of this Section 3.1(a) as if the preceding sentence’s modification had not
occurred.”
	 
	 	2.	 	As amended by paragraph 1 above, the Agreement remains in full force and
effect. This Agreement may be executed in two or more counterparts each of which shall
be deemed an original but which taken together shall constitute one and the same
instrument.

IN WITNESS
WHEREOF, the Parties hereto have executed this amendment on the 29 day of
June, 2009.

	 	 	 	 	 
	 	COMPANY:

Nabors Industries Ltd.

 	 
	 	By:  	/s/ Martin J. Whitman
 	 
	 	 	Lead Director	 
	 	 	 	 
	 
	 	Nabors Industries, Inc.

 	 
	 	By:  	/s/ Laura W. Doerre
 	 
	 	 	Its Secretary 	 
	 	 	 	 

 

	 	 	 	 	 

	 	 	 	 	 
	 	EMPLOYEE:

 	 
	 	/s/ Eugene M. Isenberg
 	 
	 	Eugene M. Isenberg 	 
	 	 	 
	 

2

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00160-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00160-of-00352.parquet"}]]