Identification of Bypassed Oil in Carbonate Buildup Reservoir at Mature Field with Integration of Saturation Log and Cement Bond Quality

The SK field operated by Pertamina EP is a mature field with RF of 41%. The main producing formation is a reef build-up carbonate reservoir. The production data shows significantly increasing water-cut, which was much faster than the cumulative production. Along with the available Fractional Flow data, this shows promising chance of production optimization. There are several key contributing factors for the water production in the SK field, i.e. water channeling behind casing due to poor cement bond, uneven production of the wells leading to varying water rise and water coning. Several efforts have been performed to optimize production, namely: identification of the potential of bypassed oil in the wells by evaluating current saturation evaluation through downhole surveillance, estimation of current water contact and cement bond improvement. Production optimization so far has been successfully achieved through comprehensive effort starting with the screening process of candidate wells, the evaluation of cement bond quality, the wellsite execution for bypassed oil evaluation and bypassed oil production. From the total of seventeen wells, fourteen wells were successfully re-perforated and put on production with incremental gain of approximately 10000 BOPD. Success rate of bypassed oil identification and production of bypassed oil is roughly 82%.