M ost wells in “MO” Field are recorded to have very high well tests results in terms of productivity index (up to more than 1000) and permeability thickness (up to 2000md). These well test results are not match with the porosity data of wells in MO field. From both porosity slices and porosity log of this field had shown uniformity and less variability than the productivity index and permeability thickness obtained by the well test. The interesting point is that the well test results are far better than the pre drill test (predicted calculation), and these well test results are suspected to be correlated with extensive vug system in “MO” carbonate reservoir with the size larger than grain size (Hakiki et al., 2015). The objective of this study is to better understand the vug size distribution from well data such as borehole image and porosity data to fetch drilling point recommendations in predicted maximum productivity area. The methodology of this project is based on qualitative analysis using Borehole Image or known as Image logs, by interpreting the vug size shown in the Image logs per half of a foot. By using this method, the variability vug size per certain depth can be seen clearly. The vug size scale was divided into 5 class: minor vugs (less than ¼ inch), minor to moderate size less than ¼ inch – ¾ inch), moderate size ( ¼ inch – ¾ inch), moderate to large size ( ¼ inch – more than ¾ inch), and large size (larger than ¾ inch). As result, less vugs are found in the drowning cap compare to the platform interior. Vugs encounter across from the cross section shown in minor to moderate size dominated, and there are some intervals with no vug in these carbonate wells. Large vugs are seen commonly associated with medium and high porosity, and found commonly in the southern part of the field. Wells with less fracture and loss zones, with many large vugs interval are predicted to have good well test results. Based on what seen in the Image logs, large vugs and other large dissolution feature in the field are resulted from hydrothermal process that flowed through, concentrated and leached the porosity along with fractures. Leached fractures then can become loss zone or pathways to loss zones.