In May 2004, INPEX made Japan Oil Development Co., Ltd. (JODCO) a wholly owned subsidiary by acquiring all of the JODCO shares held by Japan National Oil Corporation through a share exchange. Established in 1973, JODCO owns an interest in the ADMA block located offshore Abu Dhabi in the United Arab Emirates. Oil production currently spans five fields in the block. Production started from the Upper Zakum (UZ) oil field (the largest in the block) in 1982, followed by the Umm Al-Dalkh (UA) oil field in 1985 and the Satah (ST) oil field in 1987. JODCO has been involved in the development of these fields.

The Umm Shaif (US) and the Lower Zakum (LZ) oil fields have also been producing crude oil steadily since 1962 and 1967, respectively. The oil produced from these fields is transported by subsea pipelines to the islands of Das (from US & LZ) and Zirku (from UZ, UA & ST) for shipment onward.

A number of development projects are currently underway to maintain and expand oil output from the ADMA block, including plans to develop promising untapped structures in the block; construction of new gas injection facilities for the Umm Shaif field; installation of additional gas treatment facilities for the Lower Zakum field; and redevelopment plans for the Upper Zakum field that involves the use of artificial islands.

Operation and development of these fields is undertaken by ADMA-OPCO and ZADCO, the two local operating companies whose shares are owned by JODCO, Abu Dhabi National Oil Company (ADNOC) and other participating oil companies. Through JODCO, INPEX continues to assign engineers and other personnel to both of these operating companies.

INPEX acquired a 17.03% working interest in July 1970 in an offshore area in the country now known as Democratic Republic of the Congo (DRC) and has been participating in oil exploration and development in this region. An additional interest was acquired in July 1972, increasing its participating interest to the current share of 32.28%.

Oil production commenced in 1975 from the GCO oil field, which was discovered in 1971. Including GCO, a total of 11 oil fields have been discovered in the Offshore DRC block. The contract covering this block was extended until 2023 in May 1995, and production levels from existing fields remain stable.

The Egyptian Petroleum Development Co., Ltd. (EPEDECO), a joint venture established by a consortium including INPEX and Mitsui & Co., acquired a 100% working interest in the West Bakr block in June 1975. EPEDECO as operator conducted exploration activities within the block, which is located in a desert region in Egypt on the west bank of the Gulf of Suez. Three oil fields were discovered and oil production commenced in 1980.

The contract covering the West Bakr block was extended until 2020 in July 2005. Production levels from the existing fields remain stable. EPEDECO is looking to increase production through further exploration activities.

In November 2001, INPEX acquired a 10.29% working interest in the El Ouar I and II onshore blocks located in eastern Algeria. Exploratory drilling in 1997 and the subsequent drilling of appraisal wells confirmed the presence of natural gas, condensate and crude oil in the El Ouar I block. Natural gas and condensate were also found in the El Ouar II block in exploratory drilling in 2001. Joint development studies of these blocks and surrounding fields are currently ongoing.