The Use of 4D & Dynamic Synthesis in Brown Field Development: A Case Study of S-P3 Infill Well Maturation, Preparation and Drilling

Abstract

Based on the Field Development Plan (FDP), AKPO Reservoir ST was developed with two crestal producers (ST-P2 and ST-P1) and two water injectors at the periphery (ST-W2 on the eastern flank and ST-W1 on the western flank). However, the results of a time lapse seismic monitor (4D M-2) in addition to dynamic simulation showed that the attic oil of S-Reservoir would be bypassed at the end of Field life. The time lapse seismic monitor (4D M-2) results also showed that the main producer in the S-Reservoir; ST-P2 was risking early water breakthrough from the ST-W2 water injector at the toe. Hence, the need for an infill well to mitigate these identified risks. This paper presents the maturation & drilling strategy, well results and the production performance of the first infill well of the AKPO Field. The infill maturation strategy involved the update of the geological model with recent well/ 4D seismic information, evaluation of the present static uncertainties on in-place volumes, history matching of the dynamic model in line with current field behaviour and the evaluation of the incremental production and economic value of the infill well. S-P3 trajectory was designed as a sub-horizontal drain to target and produce the attic oil in the S-Reservoir up-dip of producer ST-P2. It was completed across two fault blocks to ensure drainage of the southern panel as fault behaviour remains one of the main uncertainty. The well trajectory was placed as far up-dip as possible, with its toe set higher than the shallowest completion of ST-P2 in the S-reservoir. The final well result for S-P3, drilled in Q4 2016, was outstanding, thanks to excellent integration of seismic, geological and dynamic data. The main results included: Optimal well placement, as a result of real time adjustments of the well trajectory aided by reservoir navigation toolsMore attic oil found as a result of shallower top of S-ReservoirIncremental production of 15 kboepd over 2 years and an incremental reserves of ∼10 Mboe.