Sequence Stratigraphy Applied to the Hydrocarbon Productive Basins of Western Indonesia: ABSTRACT

Abstract

Oil exploration began in Indonesia in 1870 and the first commercial discovery was made in 1885 in the North Sumatra Basin_ Since then over 3,000 exploratory wells have been drilled in Western Indonesia with some 750 discoveries reported. By the end of 1992 over 300 fields in eleven geological basins were producing in Western Indonesia and a further 100 fields were either shut-in or had been abandoned. However, despite the fact that Western Indonesia is a mature hydrocarbon province, all published work of a regional nature, and indeed most internal company reports, use lithostratigraphy and to a lesser extent biostratigraphy_ Lithostratigraphy is based, often unwittingly, on pre-1960's work when only relatively shallow wells and limited seismic were available. Additional difficulties arise from companies using alternative names for a rock unit and the same formation name for different rock units_ Biostratigraphy is handicapped by the lack of age diagnostic fossils in the Early Miocene and older sediments in most of Sumatra and Natuna_ In Java and Kalimantan, where the older section tends to be more marine and age diagnostic fossils are present, significant errors in age determination occur due to reworking of sediments_ As a consequence the 'hydrocarbon system' in Western Indonesia is inadequately understood and exploration efforts are often poorly applied_ This paper proposes a correlative framework using sequence stratigraphy for the hydrocarbon productive basins of Western Indonesia, which should contribute to a better understanding of the 'hydrocarbon system' and significantly reduce exploration risk in Western Indonesia.