A limited remaining reserve is one of the challenges commonly found in mature field development. Swamp fields in the Mahakam block is an example of mature field development which leads to a marginal operation. Delivering wells more economically is one of the key points to survive during those conditions. Rig operation with a significant daily expenditure could be a way for improvement to yield economic wells. In general, an efficient rig operation would deliver wells in a shorter duration and at a lower cost. In order to lessen the well duration, two aspects could be improved: performing co-activity operation to shorten the horizontal time (preparation) and mastering drilling practices to shorten the vertical time (drilling). In the co-activity operations aspect, various initiatives have been implemented, such as rigless operations, batch drilling, and offline or simultaneous activities. While in the drilling practices aspect, drilling parameters, bit design, connection practice, and team motivation were the areas that have been improved. This paper will elaborate further on those initiatives. Implementing massive co-activity operations and the best drilling practices have demonstrated a significant time saving of 24% for the shallow well (final depth around 1800 m) and 27% for the deep well (final depth around 4300 m) in the block. These practices have also made a new record of the fastest well completion in 2.17 days and the highest drilling ROP for 141 m/hour with drilling 2303 m in the first 24 hours. The record of most drilled length in 24 hours is the world best performance of RSS BHA as per Directional Driller Company worldwide record. As a result, the 2020 average cost of the shallow well was 2.6 MUSD while the deep well was 4.1 MUSD. Those massive co-activity operations and drilling practices have been properly executed since 2019 without any safety incident and related NPT. The positive results have helped the development project to survive in marginal conditions.

Swamp drilling operation in Mahakam has entered the industrialization period in which fast drilling is a common practice. However, fast drilling Rate of Penetration (ROP) causes hole cleaning issues to arise and induce a high Equivalent Circulating Density (ECD) trend. In some wells, this potentially leads to loss problems because of weak formation in shallow sections or depleted formation with relatively low fracture gradient. As a result, drilling parameter reduction was performed that causing lower ROP and additional circulation to reduce ECD. A new technology called Continuous Circulation Device (CCD) can help to tackle the problems mentioned above. It is a sub-based constant circulation system that enables the continuous circulation of drilling fluids downhole while making or breaking drill pipe connections. This system helps to maintain ECD and improve drilling performance as the cuttings are continuously carried out of the hole. This paper is introduced to analyze the benefits of CCD and opportunities for future development in the swamp drilling operation. The device was applied during drilling in the 12-1/4” and 8-1/2” sections. The challenge during drilling in these sections was to improve ROP without inducing bad hole cleaning that could lead to a high ECD trend. The result of CCD utilization shows that ECD during drilling could be reduced up to 2 points and become more stable compared to the previous trend. Since there was a reduction of ECD, the ROP could be improved up to 10%. Furthermore, only 1 cycle for circulation at well TD was performed as the minimum cuttings appeared. Pulling out the string and running the casing string was managed smoothly as the hole was already in a good condition. This utilization has been successfully implemented without any safety incident nor related Non-Productive Time (NPT). This positive result leads us to open the opportunity for future development in swamp fields asset.