Publications

Geological setting of Early Miocene platform margin carbonate reef build-up in the Pangkah Field offshore East Java Indonesia possesses very complex structures and reservoir properties, very intense faulting and fractures, cavern and vuggy porosity. One of the challenges faced by the subsurface team in HESS is how to identify and map the fractures. Completion decision and plan for future well placement are made based on fracture characterization. Early water breakthrough during the initial development is suspected due to some fractures combined with vuggy porosity connected to mobile water zone. The fractures are generally small in size, which may not be recognized within seismic resolution. Processed Image logs are evaluated to pick fractures, fracture density map is generated based on processed image log interpretation from all available wells, mainly in horizontal sections, and the fracture map is then used for well placement decision with simple strategy to place the wells away from the fracture zone. An improved structure map can be generated by integrating image log. When the well still penetrates a number of fractures, a form of isolation in the completion zone can be implemented. This mitigation strategy in optimizing production shows mixed results due to the complexity of the Kujung reservoirs. Later wells placed away from the fracture zone have shown positive result with low water production. However, with the level of complexity the amount of data gathered are still insufficient to image the subsurface condition accurately. It is recommended to run more image log in the future wells combined with VSP and cross-dipole sonic logs to give better image in the subsurface.