Publications

PIA-001 exploration well is located 4 km away from Donggi Gas Field, Central Sulawesi. The objective of the well is to unlock the hydrocarbon potential in Minahaki Formation. However, this is not an easy task to do. Minahaki Formation is mainly comprised of heterogeneous limestone facies, in which the primary and secondary porosity varies from facies to facies at different scales. Moreover, the diagenesis processes, such as dissolution and cementation alter each facies differently. These are the factors that introduce high uncertainty in the porosity distribution and estimation in Minahaki Formation. The conventional method to predict porosity utilizes conventional logs such as density, neutron and sonic log. However, this method is not suitable to be used in heterogeneous limestone. Its low vertical sampling rates relative to the porosity distribution, fails to predict accurately the porosity and productivity potential of these complex reservoirs. Hence, porosity needs to be generated using other type of data. The ideal data to tackle this complexity is by using electrical borehole image log which was logged within water based mud. This data is in high resolution and cover 360-degree view of borehole wall. On top of that, by using the newly developed carbonate textural and porosity estimation method, the porosity as well as the productivity potential can be accurately generated. This carbonate textural and porosity computation method has been performed in PIA-001 Well. It is observed that the secondary porosity in PIA-001 well comprises of vugs connected to fractures, vugs connected to bed boundary and connected vugs with some isolated vugs, with the total porosity ranges from 10-20%. Generally, this porosity trend shows good correlation with the porosity result from routine core analysis. Besides that, the porosity as well as the connectivity from this method is used to assist the DST interval selection. Based on this study, it can be concluded that electrical borehole image contributes to significant improvement in heterogeneous limestone porosity estimation. The porosity result also shows a good correlation with the porosity from routine core analysis and flow potential from DST Test. It is suggested to perform the same analysis to improve the success ratio in exploration well with the same reservoir challenges.