Oil and gas fields reservoired by basement rocks show that the composing rocks are never single, but consist of many types of rock (sedimentary, metasedimentary, metamorphic, intrusive and extrusive igneous rocks). Variations in production in different parts of the field will be determined by how fracturing occurs in the basement rocks. In addition, for field development, it is important to know how these basement rocks accrete to each other. Unfortunately, to know the character of these basement rocks and their accretion cannot be known significantly from the exploration carried out because it would require many exploration wells that penetrate the basement rocks. Even detailed seismic survey is not enough to do.
However, a field analogue approach can be taken, namely by looking at the accretion of basement rocks that have been uplifted to the surface, at the outcrops of basement rocks. Such an analogue field is provided by Belitung Island, Indonesia. Belitung Island is entirely composed of various types of Pre-Tertiary basement rocks and the geological mapping that has been carried out by geologists has revealed knowledge about how these basement rocks were accreted. Therefore the basement rocks accretion model on Belitung Island can be a field analogue for subsurface basement rocks which are targets for exploration and production in Sumatra, Java or Southeast Asia regionally.
Apart from that tectonically, the basement rocks of Belitung Island also prove the theory of terrane tectonics. Basement rocks on this island are rocks related to the drifting of the Indochina Terrane, opening of the Paleo-Tethys Ocean, closing of the Paleo-Tethys through subduction and collision from Sibumasu Terrane, and magmatism it caused. Most of the events related to terrane tectonics are recorded in the Pre-Tertiary tectono-stratigraphy and magmatism of Belitung Island.
This paper will first discuss the geology of Belitung Island, the interpretation of its terrane tectonics, then the application of the accretion pattern of its basement rocks for the purposes of exploration and production of petroleum in basement rocks.
This paper was presented at the Indonesian Petroleum Association Annual Convention and Exhibition 2024.
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Tektonesiana 