FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person * LIME ROCK PARTNERS V LP   2. Issuer Name and Ticker or Trading Symbol Allis Chalmers Energy Inc. [ALY] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 274 RIVERSIDE AVENUE 3. Date of Earliest Transaction (Month/Day/Year) 02/23/2011 (Street) WESTPORT, CT 06680 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/23/2011   D   19,889,044 (1) (2) D (1) (2) 0 D (3)

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

7% Convertible Perpetual

$ 2.5625

02/23/2011

D

36,393

(4)

(4)

Common Stock

14,202,146

$ 2.5625

0

D (3)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
LIME ROCK PARTNERS V LP 274 RIVERSIDE AVENUE WESTPORT, CT 06680		X
Lime Rock Partners GP V, L.P. 274 RIVERSIDE AVENUE WESTPORT, CT 06680		X
LRP GP V, Inc. 274 RIVERSIDE AVENUE WESTPORT, CT 06680		X

Signatures

/s/ John T. Reynolds, Director, LRP GP V, Inc., its general partner, Lime Rock Partners GP V, L.P., its general partner for Lime Rock Partners V, L.P		02/25/2011
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	These securities were owned by Lime Rock Partners V, L.P. ("Lime Rock"), which was a member of a "group" for purposes of Section 13(d) of the Exchange Act including Lime Rock Partners GP V, L.P. and LRP GP V, Inc. The joint filers jointly are filing this Form 4 and information regarding the joint filers other than Lime Rock Partners V, L.P. is set forth on Exhibit 99 to this Form 4. The reporting persons disclaim beneficial ownership of the reported securities except to the extent of their pecuniary interests therein, and this report shall not be deemed an admission that the reporting persons were beneficial owners of the reported securities for purposes of Section 16 or for any other purpose. (Continued in Footnote 2)
(2)	These shares were disposed of pursuant to an Agreement and Plan of Merger among the Issuer, Seawell Limited and Wellco Sub Company, a wholly-owned subsidiary of Seawell Limited, dated August 12, 2010, as amended. The Reporting Persons received 1.15 shares of Seawell Limited common stock for each share of Allis-Chalmers common stock owned.
(3)	Lime Rock directly owned all securities reported on this Form 4, all the other joint filers' ownership form is indirect, through one or more subsidiaries.
(4)	The Convertible Perpetual Preferred Stock ("Preferred Stock") was convertible into common stock at any time, at the holder's election, subject to standstill provisions and limitations on the beneficial ownership of stock above specified thresholds. These shares were disposed of pursuant to an Agreement and Plan of Merger among the Issuer, Seawell Limited and Wellco Sub Company, a wholly-owned subsidiary of Seawell Limited, dated August 12, 2010, as amended. The Reporting Persons received 1.15 shares of Seawell Limited common stock for each share of Allis-Chalmers common stock into which the Preferred Stock was convertible.
Remarks: Exhibit 99: Joint Filer Information

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