绝密

March 14, 2010March 14, 2010

CNOOC Ltd. Established CNOOC Ltd. Established Joint Venture with Bridas Joint Venture with Bridas

Energy HoldingsEnergy Holdings

CNOOC LimitedCNOOC Limited中国海洋石油有限公司

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Important Notice

This presentation includes “forward-looking statements” within the meaning of the United States Private Securities Litigation Reform Act of 1995, including statements regarding expected future events, business prospectus or financial results. The words “believe”, “intend”, “expect”, “anticipate”, “project”, “estimate”, “plan”, “predict” and similar expressions are intended to identify such forward-looking statements. These statements are based on assumptions and analyses made by us that we believe arereasonable under the circumstances. However, whether actual results and developments will meet our expectations and predictions depend on a number of risks and uncertainties which could cause our actual results, performance and financial condition to differ materially from our expectations. For a description of these and other risks and uncertainties, please see the documents we file from time to time with the United States Securities and Exchange Commission, including our 2008 Annual Report on Form 20-F filed on May 8, 2009.

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Key transaction terms

CNOOC Ltd. will form a 50%/50% joint venture with Bridas Energy Holdings Ltd (“BEH”) in Bridas Corporation (“Bridas” ).

CNOOC Ltd. and BEH will jointly make management decisions for Bridas.

Bridas is a holding company with a 40% interest in Pan American Energy (“PAE”), the second largest Argentine E&P company that is jointly owned by Bridas and BP.

Closing is subject to necessary government and regulatory approvals of People’s Republic of China, and is anticipated to occur in the first half of 2010.

The consideration for this transaction is approximately US$3.1 billion in cash.

Bridas Energy Holding Ltd

50% 50%

40% 60%

Joint-control

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Disciplined M&A Strategy

Indonesia SES: 2002

Consideration: US$585mm

16.96% interest in Indonesia Tangguh: 2003–2004

Consideration: US$275mm

45% interest in Nigeria OML130: 2006

Consideration: US$2.268bn

5.3% interest in Australia NWS: 2003

Consideration: US$348mm

Growth strategy

M&A tactics

ResourcesReturnRisk profile

Reserves and production growth

Develop natural gas

Prudent financial policy

Opportunistic

Value-driven

Return & risk evaluation

Indonesia: Malacca, SES/ONWJ, etc.

SES/ONWJ Assets,2002

Malacca PSC, 1994

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An important step of our business globalization plan

Key assets of CNOOC around the globeKey assets of CNOOC around the globe

Strategic entry into Latin America through partnership with BEH

CNOOC Ltd. Producing

CNOOC Ltd. Exploration

Bridas & affiliates

Indonesia

China

Australia

Nigeria

Myanmar

Kenya

US

Chile

Argentina

Canada

Bolivia

Trinidad & Tobago

Equatorial Guinea

Liberia

Qatar

Congo

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34% 33%25% 23%

11% 9%

-7%-10%

0%

10%

20%

30%

40%

Latin

America

Asia

Pac.

Africa &

M. East

U.S. Europe Canada Russia

10,980

289

0

5,000

10,000

15,000

2000

2001

2002

2003

2004

2005

2006

2007

2008

0

50

100

150

200

250

300

Latin America offers significant growth and resources potential…

Recent substantial discoveries in Brazil have been transformational for the upstream sector of Latin America

Strong drilling activity in the past years with record number of wells drilled during 2008

One of the fastest growing regions in capex terms

Major reserve booking potential

Positive responses from key industry players in recent licensing rounds

Source: Wood Mackenzie Pathfinder

Trend of 2p reserves discovered in Latin America (mmboe)Trend of 2p reserves discovered in Latin America (mmboe)

Wildcat wells drilled

2P Reserves discovered (mmboe)

Source: J.S. Herold

2008 capital spending increase comparison by region (yoy)2008 capital spending increase comparison by region (yoy)

Record levels for the region

Worldwide average – 21%Latin

America7%Africa9%

Other11%

M. East51%

Europe & Eurasia

22%

Total proved reserves2,347bn boe

Source: BP Statistical Review of World EnergyNotes: 1 U.S. and Asia-Pacific

Global proven reserves breakdown by region (2008)Global proven reserves breakdown by region (2008)

1166bn boe

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…with an improving investment environment

Many Latin American countries experienced stable macroeconomic and political profile in the past few years (political instability concentrated in few specific countries).

Latin-American economies have responded well to the recent crisis withfaster recovery expected in the region.

Country risks levels have decreased, as evidenced by credit rating upgrades in Peru, Colombia & Brazil.

Argentina offers a relatively stable macroeconomic environment.

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Partnership with BEH provides outstanding platform for growth…

CNOOC Ltd. believes that forming a joint venture with a local partner is critical for its success in overseas expansions.

BEH is an ideal partner for CNOOC Ltd.

Over 50 years of experiences in E&P business across Latin America, Central Asia and North America

Its on-shore oil and gas experience complements CNOOC Ltd.’s off-shore expertise

Bridas provides an unique opportunity for CNOOC Ltd. to enter into the Latin America market.

World-class asset portfolio has a large resources base

1P reserve1 of 636mmboe (38% gas) and 2009 average production of 92mboepd

Significant upside potential from projects under development and exploration

Competitive cost structures

Strong management team with a proven track record

Long-standing partnership with international oil companies

Note: 1As at December 31, 2009

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Gas, 38%

Oil, 62%

PAE has a world-class upstream asset portfolio with large resources base with exposure to Latin America

Exploration and production main blocks and reservesExploration and production main blocks and reserves

Dec 31, 2009 certified reserves (mmboe)Dec 31, 2009 certified reserves (mmboe)

Total 1P: 1,590mmboe

Attractive upstream portfolioAttractive upstream portfolio

11 producing blocks (6 PAE operated) including:

Cerro Dragon (100%)

– 60%+ of PAE reserve & production

Acambuco (52%)

Cuenca Marina Austral (25%)

9 exploration blocks, including:

GSJM Offshore(90%) — 9,000km2 acreage

Power generationOil transportation and storageGas distribution and transportation

Producing blocksExploration blocks

Cerro Dragón

Peru

Bolivia

Brazil

Paraguay

Chile

Argentina

Uruguay

Cuenca MarinaAustral (CMA)

Acambuco

GSJM Offshore

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Bridas’ upstream operations are cost competitive

Sources: Company disclosure

2008A Opex per barrel (US$/boe)2008A Opex per barrel (US$/boe)

2008A All-in cost per barrel (US$/boe) （No exploration cost included and for Bridas, Export Duty excluded)2008A All-in cost per barrel (US$/boe) （No exploration cost included and for Bridas, Export Duty excluded)

2008A DD&A per barrel (US$/boe)2008A DD&A per barrel (US$/boe)

14.8 13.310.6 9.3

8.0 7.4 6.8 6.65.2

38.7 36.2 33.4 32.8 30.5 29.523.7 19.8 17.1

17.8 15.5 15.0 14.7 14.3 12.910.8

7.04.6

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Bridas’ management team has successfully delivered strong performance growth

Bridas exhibited continued oil and gas production growth (2009 vs 2001)Bridas exhibited continued oil and gas production growth (2009 vs 2001)

Between 2001 and 2009, Bridas demonstrated an impressive track record of generating production growth in both oil and gas

Sources: Company disclosure

Oil production growth (%)Oil production growth (%) Gas production growth (%)Gas production growth (%)

47%

-20%-27%

Argentina Other Argentine

producers

101%

6%

-3%

Argentina Other Argentine

producers

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Potential upside considerations

4.0%

-4.0%

8.8%6.8%

-5%

0%

5%

10%

2003-2007 Avg. 2008 2009E 2010E

GDP growth potential of ArgentinaReal GDP growth (%)

Recovery afterimpact of crisis

Potential for

furtherrecovery

Opportunity to raise production by increasing recovery rates from mature fields using proven technologies

Source: J.P. Morgan Economic Research

Long term growth

potential

Strong energy demand driven by long term growth potential on the expected Argentine economy recovery

Favorable industry

environment

Encouragement of hydrocarbons investment by the Argentine Government through incentive programs

Petróleo Plus

Gas Plus

Significant exploration

upside

Exciting exploration portfolio of Bridas in Argentina

GSJM Offshore (acreage: 9,000km2; 3D seismic acquired: 1,700km2)

Volume upside

3D seismic acquired in

2009

GSJM

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Rest of Asia

7.5%

Latin America

8.0%Oceania 3.8%

China 80.8%

Latin America

11.2%

Rest of Asia

7.0%

Africa-ME

3.1%Oceania 4.4%

China 74.2%

Positive pro-forma impact - Immediate addition to production and reserves with geographic diversification

Latin America

100.0%

Latin America

100.0%

Net Proved Reserves (mmboe)—as at December 31Net Proved Reserves (mmboe)—as at December 31

+13%

Net production (mboepd) Net production (mboepd)

2008A CNOOC Ltd. standalone2008A CNOOC Ltd. standalone 2009A Bridas (net to CNOOC Ltd.)2009A Bridas (net to CNOOC Ltd.)

Total = 2,515mmboe Total =318mmboe

Pro-forma CNOOC Ltd.Pro-forma CNOOC Ltd.

Total = 2,833mmboe

2008A CNOOC Ltd. standalone2008A CNOOC Ltd. standalone 2009A Bridas (net to CNOOC Ltd.)2009A Bridas (net to CNOOC Ltd.)

Total = 531mboepd Total = 46mboepd

Pro-forma CNOOC Ltd.Pro-forma CNOOC Ltd.

Total = 577mboepd

Rest of Asia

7.9%

Africa-ME

3.5%Oceania 5.0%

China 83.6%

Rest of Asia

8.1%

Oceania 4.1%

China 87.8%

+9%

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10.6

16.5

11.0 10.7

CNOOC Ltd.-Bridas Latest transaction

(Pluspetrol/PetroAndina)

Argentina median LatAm median

Implied valuation consistent with precedent transactions

Source: HeroldNote: Multiples based on enterprise value1 Includes only transactions with total consideration size larger than US$100mm2 Includes 6 transactions: Oxy—Vintage (2005), Apache—Pioneer (2006), PAE—Apache (2006), Petrobras—Noble (2007), Delta—Trefoil (2008), Pluspetrol—PetroAndina (2009)3 Includes 19 transactions: 7 in Colombia, 6 in Argentina, 3 in Venezuela, 2 in Peru and 1 in Ecuador

Proven reserve multiples of Argentine and Latin American E&P transactions since 2005 (US$/boe)1Proven reserve multiples of Argentine and Latin American E&P transactions since 2005 (US$/boe)1

2 3

Nov 2009

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Closing Remarks

World-class asset portfolio with a large resources base

Significant upside potential from projects under development and exploration

Industrial logic and upsideIndustrial logic and upside

Strategic entry into Latin America

Partnership with potential for global expansion

Another step of globalizationAnother step of globalization

Bridas Energy Holding Ltd

50%Joint-control

40%

50/50 partnership with BEH with a joint control over Bridas

Benefiting from BEH’sextensive industry expertise and unmatched local market knowledge

Strategic partnership with BEHStrategic partnership with BEH

50%50%