Quality Assurance Reserve Process

1
Quality AssuranceReserve Process

• Reserves are calculated by professionals degreed
  in engineering and geology
• Calculations are reviewed by business units
  qualified experts
• Business Unit Vice President and experts make
  representation that annual reserve estimates are
  in accordance with SEC standards
• In aggregate, a rotating 50 of the asset base
  and 90 of changes reviewed by the corporate
  review team
• Leader reports directly to the CFO
• No team member has direct or indirect management
  ties to the business unit under review
• All team members are considered an expert in
  their discipline
• No team member has a reserve volume goal
• One member from independent 3rd party (Ryder
  Scott)
• Material changes reviewed by Management Committee
• Letter of Confidence issued by Outside Audit Firm

2
2003 Proved Hydrocarbon ReservesAudit Coverage
Total 1,759 Million BOE
Audit Team Review
33
Not Reviewed In 2003
Audit Team Partner Review
11
23
33
100 of Major Changes Reviewed Every Year 95
of All Changes Reviewed in 2003
Third Party Review
3
Unocal Reserves Production
Reserves (MMBOE) 12/31/2003
Production (MBOE/D) 2003 Average
Other Intl. 17
Other Intl. 8
Far East 50
Lower 48 32
Far East 46
Lower 48 21
35
293
145
373
883
205
31
101
109
32
Alaska 7
Alaska 6
Canada 6
Canada 7
Total 448,200 barrels of oil equivalent per day
64 gas 36 oil
Total 1,759 million barrels of oil equivalent
62 gas 38 oil
4
Thailand Proved Undeveloped Reserves343 Million
BOE

• Current Production is Pipeline Limited
• Net Sales Commitments expected to rise from 590
  MMCFPD to 920 MMCFPD, contract extension to 2022
• Third Pipeline is under Construction Est.
  Completion 2006
• Thailand has a long history of just-in-time
  Development and routine promotion of PUD units to
  PDP and Production.
• In order to justify Thailands investment in
  Pipelines and Power Plants the government
  requires assurance of Proved Reserves for future
  needs.
• Thai National pipeline company reviews Unocals
  reserve estimates as part of their due diligence

5
2003 Year-End Preliminary Proved Undeveloped
Hydrocarbon Reserves
West Seno Phase 1 2 AIOC Merah Besar Mad
Dog K2 Ranggas
Major Developments 40
All Other 21
Thailand 39
P.U.D. 874 Million BOE Total 1,759 Million BOE