POST-MORTEM ANALYSIS OF DRILLING FAILURE OF KAYAN-1 AND KEDUKUL-1 WELLS IN MELAWI BASIN, WEST KALIMANTAN

摘要

Melawi Basin is one of the basins in Indonesia that has hydrocarbon potential as is indicated by the gas shows encountered by wells and oil seepages at surface. These suggest that the petroleum system in this basin is active. Historically, the basin has attracted some companies to conduct exploration which is marked by the drilling of two wells: Kayan-1 in 1986 and Kedukul-1 in 1995. The drilling reports stated that both wells are dry with gas shows. Therefore, the purpose of this study is to determine the cause of the drilling failure of both wells from a point of view of geological sciences. The research method included analyzing the wells (Kayan-1 and Kedukul-1), seismic data, and research reports to determine the petroleum system in this basin, then by performing further analysis to understand part of the petroleum system components that are not active. Results of the study showed that the potential of the source rock at Kayan-1 and Kedukul-1 is the Ingar Formation. Potential reservoir rocks at Kayan-1 have porosity less than 10% in the upper part of the Ingar Formation and Dangkan Formation. In Kayan-1, the gas shows were observed in the Ingar Formation, Dangkan Formation, and Tebidah Formation. In Kedukul-1. the gas shows were found in the Ingar and Tebidah Fonnations. The Sintang Intrusion occurred in Oligocene - Miocene is found in the several locations and formed some anticlines in Melawi Basin. In Kayan-1 well, the intrusions intruded the Ingar and Dangkan Formations, while in Kedukul-1 the deepest penetrated rocks was the Sintang Intrusion. Conclusion of the study suggests that the drilling failure of Kayan-1 are caused by poor source rock, poor reservoir rock, and the leaking of trap that formed by Sintang intrusion. Drilling failure of Kedukul-1 are caused by the leaking of trap and Sintang intrusion that cause hydrocarbon leaking to the surface.