| Popis: |
Completion phase is critical in well construction where drilling operation is achieved in static-underbalanced condition with water as circulation fluid. With utilization of Managed Pressure Drilling (MPD) equipment that consists of Rotating Control Device (RCD), Automated MPD Choke Manifold, and Downhole Isolation Valve (DIV), lower completion string can be deployed safely and efficiently. MPD technique enables safe and efficient transition after reaching target depth and prior running lower completion. The same technique allows instant and manageable bottom hole pressure upon the completion phase. This paper emphasizes the main benefits of MPD technique while running lower completion in a gas-rich well in South Sumatra. With static-underbalanced fluid presence while drilling to target depth, transition from drilling to completion phase is very crucial. The presence of DIV eliminates the needs to kill the well with heavier mud and chemical additives prior tripping out drill string to surface. DIV isolates the open-hole formation safely while drill string is pulled out and lower completion string is made up on surface. This result in easier fluid management on surface by keeping fresh water as circulation fluids, while avoids chemical settling to the pay-zone which can lead to well productivity issues. While running the completion string, prior to reaching DIV depth, RCD bearing assembly is installed to enable closed-loop and pressure-able drilling system. The DIV is then opened securely while MPD Automated Choke Manifold manages the desired bottom hole pressure by adjusting the surface back pressure accordingly. Although the fluid weight in the well is static-underbalanced, the bottom hole pressure is managed to be overbalance at all time. Lower completion string is run to bottom then its hanger and packer set subsequently to have the primary well barrier in place for further production purpose. |
