Publications

Bangko Field in Sumatra Light North (SLN) area is contributing around 5% of the overall oil production in Sumatra. Bangko Field is mainly producing oil from 2 oil bearing zones: The Duri formation @ 1600’SD and the Telisa formation @ 1530’SD. The Duri formation is a high permeability sand, meanwhile the Telisa formation has a low permeability. The initial production of the Duri sand has a 95% water cut, while the Telisa formation is only 50% water cut. It became clear that production could be easily improved if the Telisa formation production was optimized. The operator decided to drill horizontal wells in Telisa in order to increase oil production by increasing the length of the contact zone. Good cement coverage across the horizontal section is essential since the casing was to be perforated and stimulated by Hydraulic Fracturing technic in multiple stages before running the completion. Horizontal well cementing presents more challenges than cementing in a vertical well, due to uneven wellbore geometry created by the friction of the drill string in the open hole, the accumulation of cuttings at the bottom side of the annulus, open hole eccentricity. In these conditions stable cement slurry is essential to guarantee good zonal isolation and avoid trapped pockets of left over mud. This paper will detail what processes and technics were implemented to design and execute cement jobs in these horizontal wells: centralization of pipe, spacer type selection, slurry testing and optimization and mud removal techniques. Finally we will show the results on 2 cementing jobs performed in the Telisa horizontal Project. These successful designs and execution of cement jobs will achieve good zonal isolation for the long term life of the well and eliminates the need for a remedial squeeze job prior to stimulation.