Filed by Seawell Limited. Pursuant to Rule 425

Under the Securities Act of 1933

And Deemed Filed Pursuant to Rule 14a-12

Under the Securities Exchange Act of 1934

Subject Company: Allis-Chalmers Energy Inc.

Commission File No. of Subject Company: 001-02199

This filing relates to the proposed merger of Wellco Sub Company, a wholly owned subsidiary of Seawell Limited, with Allis-Chalmers Energy Inc., pursuant to the terms of an Agreement and Plan of Merger, dated as of August 12, 2010, by and among Seawell Limited, Wellco Sub Company and Allis-Chalmers Energy Inc..

Forward-Looking Statements

This communication contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.  Forward-looking statements are typically identified by words or phrases such as "will," "anticipate," "estimate," "expect," "project," "intend," "plan," "believe," "target," "forecast," and other words and terms of similar meaning.  These forward-looking statements involve a number of risks and uncertainties.  Seawell and Allis-Chalmers caution readers that any forward-looking statement is not a guarantee of future performance and that actual results could differ materially from those contained in the forward-looking statement.  Such forward-looking statements include, but are not limited to, statements about the benefits of the proposed merger involving Seawell and Allis-Chalmers, including future financial and operating results, Seawell's and Allis-Chalmers' plans, objectives, expectations and intentions, the expected timing of completion of the transaction, and other statements that are not historical facts.  Important factors that could cause actual results to differ materially from those indicated by such forward-looking statements are set forth in Allis-Chalmers’ filings with the Securities and Exchange Commission.  These include risks and uncertainties relating to: the ability to obtain the requisite Allis-Chalmers stockholder approval; the risk that Allis-Chalmers or Seawell may be unable to obtain governmental and regulatory approvals required for the merger, or required governmental and regulatory approvals may delay the merger or result in the imposition of conditions that could cause the parties to abandon the merger; the risk that a condition to closing of the merger may not be satisfied; the timing to consummate the proposed m erger; the risk that the businesses will not be integrated successfully; the risk that the cost savings and any other synergies from the transaction may not be fully realized or may take longer to realize than expected; disruption from the transaction making it more difficult to maintain relationships with customers, employees or suppliers; the diversion of management time on merger-related issues; general worldwide economic conditions and related uncertainties; and the effect of changes in governmental regulations.  Neither Seawell nor Allis-Chalmers undertakes any obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise.

1

Additional Information and Where to Find It

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. The publication or distribution of this communication may, in some countries, be restricted by law or regulation. Accordingly, persons who come into possession of this document should inform themselves of and observe these restrictions. To the fullest extent permitted by applicable law, Seawell, Allis-Chalmers and their respective affiliates disclaim any responsibility or liability for the violation of such restrictions by any person. In connection with the proposed merger between Seawell and Allis-Chalmers, Seawell will file with the SEC a Registration Statement on Form F-4 that will include a proxy statement of Allis-Chalmers that also constitutes a prospectus of Seawel l.  Seawell and Allis-Chalmers will mail the proxy statement/prospectus to the Allis-Chalmers stockholders.  Seawell and Allis-Chalmers urge investors and stockholders to read the proxy statement / prospectus regarding the proposed merger when it becomes available, as well as other documents filed with the SEC, because they will contain important information. You may obtain copies of all documents filed with the SEC regarding this transaction, free of charge, at the SEC's website (www.sec.gov).  You may also obtain these documents, free of charge, from Seawell's website (www.seawellcorp.com) under the tab "Investors.”  You may also obtain these documents, free of charge, from Allis-Chalmers' website (www.alchenergy.com) under the tab "For Investors" and then under the heading "SEC Filings."

Participants In The Merger Solicitation

Seawell, Allis-Chalmers, and their respective directors, executive officers and certain other members of management and employees may be soliciting proxies from Allis-Chalmers stockholders in favor of the merger and related matters.  Information regarding the persons, who may, under the rules of the SEC, is deemed participants in the solicitation of Allis-Chalmers stockholders in connection with the proposed merger will be set forth in the proxy statement/prospectus when it is filed with the SEC.  You can find information about Allis-Chalmers' executive officers and directors in its definitive proxy statement filed with the SEC on April 30, 2010.  Additional information about Seawell's executive officers and directors and Allis-Chalmers' executive officers and directors can be found in the above-refere nced Registration Statement on Form F-4 when it becomes available.  You can obtain free copies of these documents from Seawell and Allis-Chalmers using the contact information above.

2

Seawell Limited

International Drilling & Well Services Company

Jorgen P. Rasmussen, Executive Chairman of the Board

September 2010

Photo: Harald Pettersen / Statoil

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Sales

EBITDA

Page 2

Seawell Limited 2003-2010

CAGR 2003-2009

Revenues +25%

EBITDA +29%

Page 3

Agenda

•The Oil Services market

•The Seawell business concept

•Acquiring Allis-Chalmers

•Seawell value proposition: Global footprint

•Seawell value proposition: Technology

•Seawell value proposition: Customers

•Seawell value proposition: People

•Summary

Page 4

The Market, Oil Services, Wellbore Focus

The world needs to increase energy supply

•Population adding 200,000 people per day

•By 2015 we are more than 7 Billion people on earth

•Non-OECD countries are growing much faster than OECD
countries

•The world needs to get from 86 million barrels per day to 100
million barrels to meet 2030 demand

•70 percent of the oil comes from fields with more than 30
years of production

•Increasing decline rates highlights the need to improve
recovery rates

Page 5

Norway Oil Production -- 40 years 7000 BNOK

Source NPD

Must be Drilling More wells

To produce the Light blue

Page 6

The Industry Challenge: Improve Oil Recovery

”…we need to find cost-effective ways to allow two or
three times more production wells to be drilledper
year, we need to accept a higher risk by using the
newest technology to drive out more reserves…”

Kjell Pedersen, President and CEO of Petoro a.s. ONS, August 2010

Seawell is focused on (1) drilling all kinds of production wells
and (2) mechanical repairs on production wells

Page 7

Page 8

The Seawell Business Concept

The Leading Independent Oil Services Company

•Customers are at the center of all we do

•We focus on the development of our customers’ existing fields

•We only do work directly connected with the well

•We focus on well services and drilling skills

•We recruit and develop diversified personnel

•We are able to perform integrated drilling and well
intervention operations

•We will work onshore and offshore

•We will deploy our technology and services through a global
footprint

Page 9

The Leading Independent Oil Services Company

•Tier 1 customers

•Quality personnel

•Strong management

•Superior technology

•Global footprint

•Healthy balance sheet

•Competent Board

•Active owners

•Stock exchange listing

Strong organic growth

Modular rig

Peak Well Solutions

Tecwel

C6

RIS

Allis-Chalmers: pending

2007-2010

2010 à

Our toolbox to growth

1) Incl. BJ Services 2) Incl. Smith International

CAGR 2003-2009

Revenues +25%

EBITDA +29%

466

1 019

1 056

1 079

1 114

1 449

8 827

13 786

14 675

30 921

0

5 000

10 000

15 000

20 000

25 000

30 000

35 000

Seawell

2007

Expro

Complete

Key

Energy

SEAW

+

ALY

Superior

Energy

Weather-

ford

Baker

Hughes

Halli-

burton

Schlum-

berger

1)

2)

Page 10

Drilling Services

Bits

Motors

Rotary steerable

MWD / LWD

Collars / Pipe

Platform / Land drilling

Carbon technology (C6)

Tractor services

Well intervention

Fishing

Production logging

Well Services

Slickline / E-line

Mechanical tools

Integrity logging

Engineering Services

Facilities engineering

Upgrades and Maintenance

Casing

Barrier Plugs

Perforations

Drilling optimization

The Well Company

Page 11

Page 12

Our World Leading Positions

•No. 1 platform driller

•Largest drilling facility engineering house

•Modular and mobile platform drilling rig

•Ultrasonic camera and leak detection tools

•World leading mechanical barrier plug (HPHT and VMB)

•Wireless operated cementing head

•Composite cable for well intervention

Acquisition of Rig Inspection Services
Significant synergies

•Inspection and validation of rig & equipment,
OCTG surveys, and assessments

•RIS based in Singapore and Australia, operating
on a global basis.

•Tier one customer base: Transocean, Seadrill,
Diamond Offshore, Chevron, BHP, Shell,

•Completes Seawell’s asset integrity offering

•Significant market potential: market potential for
Seawell in marine riser inspection market in the
range of USD 40-50m

Analyse

Inspect

Assess

Modify, Upgrade,
Repair &
Maintain

Front end

engineering

RIS will leverage on Seawell’s global customer network
and become a world leading inspection company

Page 13

Page 14

Acquiring Allis-Chalmers

1Source: 2009 annual report. Numbers in pies: USDm, relative share of total.

2Source: 2009 annual report. Defined as long-lived assets. Total assets of USD 1080.6m

2009 revenues by geography

Assets per 31.12.20092

Argentina

244

48 %

US

188

37 %

Brazil

44

9 %

Other Intl.

30

6 %

Argentina

169

19 %

US

572

65 %

Brazil

82

9 %

Other Intl.

59

7 %

Page 15

Introduction to Allis-Chalmers Energy Inc

•Provider of services and equipment
to oil and natural gas E&P
companies

•Operations in US, Argentina, Brazil,
Bolivia and Mexico

•Employs approximately 3,300 skilled
and experienced people

•Three business segments

•Oilfield Services

•Drilling and Completion

•Rental Services

•Listed on NYSE

•Largest shareholder is Lime Rock
Partners

Key figures1

1Source: ThomsonOne

Page 16

The Well Company

Combining strengths of SEAW & ALY

•6,500+ employees in 30+ countries

•USD 1.3 billion revenues in 2010, USD 195
million in EBITDA1

•Leading oilfield service company in North
Sea

•Major onshore player in the Americas

•30+ years experience in drilling and
servicing production wells

•A compelling range of cutting-edge
downhole technologies

Page 17

Seawell Value Proposition:
Global Footprint

Global footprint is key to maximize value

Global distribution platform for technology
and services

Page 18

Page 19

A global footprint = Customer access

•“We are focused on reaching 40+ locations globally as soon as
possible through geographical expansion and acquisitions.”

•“ The key to our success is for Seawell to acquire and develop
technologies and services that improve the performance of
well construction, well maintenance and well repairs, and then
be able to distribute those technologies and services through
a global network.“

Page 20

Seawell Value Proposition:

Technology - Focused on the Well

C6 Technologies AS
A step change in intervention technologies

•To develop and
manufacture advanced
next-generation well
intervention products and
integrated intervention
systems

•Global ambitions both on
and offshore

•Independent solutions
provider

•Seawell and IKM Group
joined forces to bring well
intervention expertise,
equipment manufacturing
capability, and global
footprint.

C6 Technologies portfolio will include next-generation deployment
systems and a range of down hole tools for integrated well
intervention operations

Carbon
Cable
Technology

“ComTrac”

Long Reach
Conveyance

Acquisition

System

Integration

Mechanical

Tools

& Services

C6

Technologies

Page 21

Comtrac-the foundation for the futureA step change in conveyance technology

•Reduce requirement for use of tractors
by 40-60 %

•Cost savings of 40-50 % compared to
current tractor operations

•Significant improvement in potential for
power transmission

•Global market application

•Fiber optic / FBG for online strain and
tension / compression of the cable

Comtrac is a step change for the wire line market and will take a
significant part of the tractor market

Page 22

Seawell EMERALD Flexible Drilling Machine

Our goal is to build a global modular rig division
in the next 5 years

Our new Modular rig is on plan to be
completed in Germany Q3 2010, and we
expect delivery in Q4. Several options for the
initial contract are being pursued.

To maximise flexibility the rig has been designed
with the capability for the following services:

Drilling

Snubbing

Workover

Complex completions

Casing while drilling (CwD)

Managed pressure drilling (MPD)

Plug & abandonment (P&A)

Page 23

Ultrasound camera “sees” through casing

Well Performance Eye- WPE

Page 24

Results - Blowout preventer in HP gas well

Well Performance Eye- WPE

Page 25

The Peak VMB Plug is a mechanical multiple set and
retrievable casing/liner Plug.

Designed as a primary or secondary well barrier and
tested according to ISO 14310 V0

(gas tight).

ELEMENTS

Unique resetable packing
element system.

V0 certified reinforced
elements.

745 Bar/10 800 PSI.

130 C°/266 Fahrenheit.

Page 26

World Leading Barrier PlugVMB

Page 27

Seawell Value Proposition:

Tier 1 Customers

Unit

Customer

Gullfaks A, B, C

Veslefrikk A, B

StatoilHydro

Statfjord A, B, C

Ula & Valhall

Gyda

Brent A, B, C, D, Nelson

Dunlin

Eider, Tern, N.Corm., Corm.A

StatoilHydro

StatoilHydro

BP

Talisman

Shell

Fairfield

TAQA

2009

1Q2Q3Q4Q

2010

1Q2Q3Q4Q

2011

1Q2Q3Q4Q

2012

1Q2Q3Q4Q

2013

1Q2Q3Q4Q

Alba & Captain

Chevron

Forties A, B, C, D

Apache

Brae A, B, E

Marathon

Firm contract’s

Option

Ekofisk & Eldfisk

ConocoPhillips

1 x 2 year

Life of field

1 year

3 x 1 year

3 x 1 year

Year to year

Peregrino A & B

StatoilHydro

1 x 2 year

1 x 2 year

Life of field

1 year

Option 5 x 5 year

Option 2 x 3 year

37 Rigs

37 Rigs

20 Operating Strings

20 Operating Strings

Page 28

Contract Status - 2 Billion USD backlog

Page 29

Seawell Value Proposition:

People

Seawell - Deliver What Is Promised

CAGR 2003-2009

Revenues +25%

EBITDA +29%

Page 30

Disclaimer

Confidential

Forward-Looking Statements

•This communication contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995.Forward-looking
statements are typically identified by words or phrases such as "will," "anticipate," "estimate," "expect," "project," "intend," "plan," "believe," "target,"
"forecast," and other words and terms of similar meaning.These forward-looking statements involve a number of risks and uncertainties.Seawell and Allis
- -Chalmers caution readers that any forward-looking statement is not a guarantee of future performance and that actual results could differ materially from
those contained in the forward-looking statement.Such forward-looking statements include, but are not limited to, statements about the benefits of the
proposed merger involving Seawell and Allis-Chalmers, including future financial and operating results, Seawell's and Allis-Chalmers' plans, objectives,
expectations and intentions, the expected timing of completion of the transaction, and other statements that are not historical facts.Important factors that
could cause actual results to differ materially from those indicated by such forward-looking statements are set forth in Allis-Chalmers’ filings with the
Securities and Exchange Commission.These include risks and uncertainties relating to: the ability to obtain the requisite Allis-Chalmers stockholder
approval; the risk that Allis-Chalmers or Seawell may be unable to obtain governmental and regulatory approvals required for the merger, or required
governmental and regulatory approvals may delay the merger or result in the imposition of conditions that could cause the parties to abandon the merger;
the risk that a condition to closing of the merger may not be satisfied; the timing to consummate the proposed merger; the risk that the businesses will not
be integrated successfully; the risk that the cost savings and any other synergies from the transaction may not be fully realized or may take longer to
realize than expected; disruption from the transaction making it more difficult to maintain relationships with customers, employees or suppliers; the
diversion of management time on merger-related issues; general worldwide economic conditions and related uncertainties; and the effect of changes in
governmental regulations.Neither Seawell nor Allis-Chalmers undertakes any obligation to publicly update any forward-looking statement, whether as a
result of new information, future events or otherwise.

Additional Information and Where to Find It

•This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. The
publication or distribution of this communication may, in some countries, be restricted by law or regulation. Accordingly, persons who come into possession
of this document should inform themselves of and observe these restrictions. To the fullest extent permitted by applicable law, Seawell, Allis-Chalmers
and their respective affiliates disclaim any responsibility or liability for the violation of such restrictions by any person. In connection with the proposed
merger between Seawell and Allis-Chalmers, Seawell will file with the SEC a Registration Statement on Form F-4 that will include a proxy statement of Allis-
Chalmers that also constitutes a prospectus of Seawell.Seawell and Allis-Chalmers will mail the proxy statement/prospectus to the Allis-Chalmers
stockholders.Seawell and Allis-Chalmers urge investors and stockholders to read the proxy statement / prospectus regarding the proposed merger when it
becomes available, as well as other documents filed with the SEC, because they will contain important information. You may obtain copies of all documents
filed with the SEC regarding this transaction, free of charge, at the SEC's website (www.sec.gov).You may also obtain these documents, free of charge,
from Seawell's website (www.seawellcorp.com) under the tab "Investors.”You may also obtain these documents, free of charge, from Allis-Chalmers'
website (www.alchenergy.com) under the tab "For Investors" and then under the heading "SEC Filings."

Participants In The Merger Solicitation

•Seawell, Allis-Chalmers, and their respective directors, executive officers and certain other members of management and employees may be soliciting
proxies from Allis-Chalmers stockholders in favor of the merger and related matters.Information regarding the persons, who may, under the rules of the
SEC, is deemed participants in the solicitation of Allis-Chalmers stockholders in connection with the proposed merger will be set forth in the proxy
statement/prospectus when it is filed with the SEC.You can find information about Allis-Chalmers' executive officers and directors in its definitive proxy
statement filed with the SEC on April 30, 2010.Additional information about Seawell's executive officers and directors and Allis-Chalmers' executive officers
and directors can be found in the above-referenced Registration Statement on Form F-4 when it becomes available.You can obtain free copies of these
documents from Seawell and Allis-Chalmers using the contact information above.

Page 31