Low Quality Reservoir Infill Development – Case Study of Kotabuana Field
Authors: Yogasugama Mario Andre , Prasetio Mario Hadinata , Rahman Aulia , Aulia Desymouna , Yunitasari Indriani , Krisnanda Fabiola Lady , Lasmono M Shindu Arya , Afifabyan Muhammad Naufal , Aditya Rachmad Fachri , Mekarsari Rinie , Jauhari Usman , Putra Rendy Maylana , Rakasiwi Dadali , Sutyastomo Dwiyanto , Irfan Muhamad 
Published: October 2023

Oil field development tends to prioritize its most advantageous features first in maximizing revenue. One of the most common way of such effort is to prioritize the development of High Quality reservoir. Kotabuana field also follow such practice. With the vertical reservoir divided into two main formation such as Tenares and Bekalo, the development of Bekalo reservoir which has significantly better reservoir quality was prioritized since the discovery of the field back in 1970s.

The development of Tenares reservoir through infill drilling expansion was initiated as continuation effort following up the recent Tenares Optimization campaign from existing well that started in 2018 with major improvement in completion selection and pressure maintenance strategy leveraging key lesson learned from previous development effort such as single Tenares completion to maximize the sand's production contribution, minimizing the crossflow tendency from Bekalo reservoir that has contrast influx due to its significantly better reservoir property and driving mechanism. It was balanced by injection strategy by adding single sand Tenares injector to maximize the injection allocation towards Tenares reservoir.

The development scenario selected was based on the simulation result that aimed towards the exploitation of the remaining oil that shown in the Movable Oil Index (MOI) map. Once the remaining oil was located, the next step is identifying detailed well placement that depends on the reservoir property. New injectors were placed in the lack of pressure area identified by Pore Pressure Index (PPI) map to provide pressure support to new and nearby existing producers. Proppant fracturing was also proposed in the infill wells to allow the production and improve injection distribution.

The infill drilling execution was done smoothly without significant problem during the execution. The challenge, however, lies in the surface location preparation that leads on the delay of the injector drilling. This delay created a disruption in production stage where the multiple findings of operational problem due to lack of pressure support that required extensive troubleshooting and optimization effort to minimize the operational problem.

Despite of the challenges, the current development provides a total production incremental with an average initial production of105 BOPD out of current 25 wells put on production. The infill candidates that located outside of the current Tenares Area of Interests also opens new opportunity area in expanding the depletion plan without disrupting most of the existing wells that already drained from prime location. the development of LQR also provides another benefit in the brown field development strategy that usually requires a larger gross production fluid to maintain the target oil production. With its typical low fluid production, the electricity consumption can be reduced and avoid the necessity of upgrading the gathering station fluid processing capacity.