Publications

The Kurnia-1 well was drilled as the first test of the Kujung Formation in the South Madura exploration block on Madura Island in the East Java Basin. The well was drilled to test a large anticlinal structure mapped on 2D seismic data. The well encountered very strong mudlog gas shows that persisted throughout the Kujung section. An open-hole production test flowed hydrocarbons to surface, but mechanical problems caused the test to be abandoned without determining a flow rate. Evaluation of wireline and Logging While Drilling (LWD) logs and sidewall cores from Kurnia-1 indicated that the Kujung Formation carbonates are characterised by low matrix porosity, however, borehole resistivity and azimuthal density images reveal a high degree of fracturing, raising the possibility of a fractured reservoir play. The objective of this study was to evaluate the viability of a fractured reservoir. Mudlog, LWD and wireline logging data and borehole image log analysis were integrated in order to indentify and characterise fractures in the Kujung carbonates based on their orientation and image characteristics. The study has confirmed strong fracture density in the Kujung Formation and that zones of greatest fracture intensity also had the strongest gas shows. Fractures have been assigned to three orientations and these fracture sets have been integrated into a coherent structural framework. In the absence of production data, a qualitative assessment of permeability potential has been made based on fracture characteristics and orientation relative to local and regional structures. The results of the study indicate the Kujung Formation in the South Madura block is a potentially viable fractured reservoir.