Publications

The natural fractured basement reservoirs become an obsessive target in Jabung Block. Currently, there are two wells drilled in the block that targeting fractured basement reservoir. They are the NEB Base-1 well that located in western part of the NEB Field and the NEB Base-2 well which located 7 kilometers away to the East of NEB Base-1 well. The first well was technically success, however NEB Base-2 well shows no indication of hydrocarbon influx during the test. Interestingly, the fractures development in both wells shows almost the same condition of fractures orientation, dip-magnitude and fractures intensity. Furthermore, each fracture in both wells can be correlated into several zones, as they indicate similar fracture set orientation at each zone. These findings create a big question, why the similar fractures characters show a very different test result? This study is intended to have that question answered with the idea to focus on the following two workflows: the first is to re-evaluate the previous works starting from re-picking the seismic fault in detail. The second is to analyze the relationship between geomechanical forward modelling result with the structural evolution in Jabung Block through sandbox modelling. The geomechanical forward modelling in the NEB Field imply the critical stress stated that was predominantly located in the western part or within the NEB Base-1 area., This result is strongly correlate with the new basement fault map which shows an intensive faulting in the western area, and is characterized by couples of synthetic-antithetic Riedel shear as a result of the strike-slip faulting. In addition, the sandbox modelling shows a major oblique-slip fault movement was observed within the western area. Therefore, it can be concluded that the intensive strike slip fault plays an important role to enhance the connectivity between fault and fracture to the hydrocarbon storage as shown in the result of NEB Base-1 well. This idea could be used as a guidance to explore another fractured basement prospect within the block.