Abstract

Typical of many onshore areas in Indonesia, the Corridor area in the South Sumatra basin has experienced several cycles of petroleum exmploration over the past century. B.P.M. (Shell) initiated the first exploration cycle in the early 1890's resulting in the discovery of several small, shallow oil fields. Intense prospecting for additional shallow Air Benakat fields continued until 1921, when large oil reserves were discovered in deeper Talang Akar Formation sandstones in the South Palembang basin. A second cycle of petroleum activity extended through the 1930's and was terminated by the outbreak of World War II. Drilling concentrated on deep Talang Akar prospects similar to those found to be so productive to the south. A low level of exploration activity occurred in this area post World War II through the late 1960's.

A cycle of modern exploration in the Corridor Block was initiated by Stanvac in early 1971, when they farmed in to a Technical Assitance Contract obtained by Redco in 1968. Between the period January 1971 to January 1977, Stanvac shot 3883 kms of 6 and 12-fold seismic data and drilled 20 wildcat wells (5 Air Benakat Fm. and 15 Talang Akar Fm. tests). However, no new oil fields were discovered and Stanvac returned the block to Redco (Asamera) in early 1977.

Asamera, with Bow Valley as a new farmin partner, commenced a wildcat drilling program in 1980, and derived additional prospects from a 1981–82 seismic survey. In 1982, two commercial oil fields were discovered: Tanjung Laban and Ramba.

Acquisition of more good quality, 24-fold seismic data in 1982–83; a 'play' concept exploration approach; and integrated seismic and geological mapping led to additional oil and gas discoveries at Supat, Tengah, and Rawa in 1984. Importantly, a new, and possibly extensive, Batu Raja Limestone stratigraphic oil play has been recognized in this relatively mature exploration area. Also, new seismic data, well control and careful structural geological analyses have led to recognition of numerous shallow prospects near old oil fields.

Perhaps other explored basin areas in Indonesia may also contain opportunities for significant new oil discoveries. These could exist in subtle stratigraphic traps and in structurally complex areas, where current seismic and well data give a mistakenly oversimplified trap configuration.