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 and LZ) and Zirku (from UZ, UA and ST) for shipment.

A number of development projects are currently under way to maintain and expand oil output from the ADMA Block, including plans to develop promising untapped structures in the block, the construction of new gas injection facilities for the Umm Shaif field and redevelopment plans for the Upper Zakum field that involve the use of artificial islands.

The operation and development of these fields is undertaken by ADMAOPCO and ZADCO, the two local operating companies for which the shares are owned by JODCO, Abu Dhabi National Oil Company (ADNOC) and other participating oil companies. Through JODCO, INPEX continues to dispatch 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 the 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, 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.

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.