Drilling activity in Seram Island block is one of the most active in the Eastern Region of Indonesia. Drilling operator in the block has conducted drilling of 2 (two) exploration wells, where one of the well reached total depth to 19,230 ft. The well is one of the deepest onshore well in Indonesia. Both exploration wells have target to penetrate Manusela Formation as objective reservoir.
Actual drilling depth of the first exploration well LFN-1 in LFN field is 14,525 ft and the second well LFN-2 is 19,230 ft. The drilling effort in the LFN field faced many challenges, such as those experienced in LFN-1 well during drilling 8-1/2" hole section in Lower Nief formation whose lithology is limestone, partial loss occurred and in the consecutive formation of Kola with Shale whose lithology contained overpressure zone resulting in kick and well control effort has to be taken. This shows that the drilling operation in 8-1/2" hole section there is a narrow window of pressure regime between Pore Pressure (PP) and Fracture Pressure (FP) which is estimated to be ± 2 ppg. Thus drilling operator is required to use the latest method or technology to overcome the challenges and to finish drilling safely.
Efforts that were made to minimize operation problems in well LFN-1 have been analyzed and learned to be improvement on well LFN-2. One of the solutions selected was to use current well-known technology which is Manage Pressure Drilling (MPD) method on well LFN-2. The MPD is to be utilized on 8-1/2" hole section. The purpose of the application of the MPD method is to keep the Bottom Hole Pressure (BHP) to be constant in between Pore Pressure (PP) and Fracture Pressure (FP) thus minimizing the occurrence of losses and kick at the same time. The advantages of MPD usage are that we can make BHP constant during pipe connection so the hole does not allow kick and at the time of drilling, as it passes through the overpressure zone which is up to 17 ppg, the influx can be detected and anticipated quickly.
With the application of MPD method on LFN-2 well in 8-1/2" hole section, LFN-2 well could go according to plan and there was no problem as experienced before in well LFN-1. This is a good achievement in improving the performance of drilling at exploration wells with depth up to 19,230 ft.