Overcoming a 0.35 ppg Mud Weight Window - A Case History of Successful Automated Managed Pressure Drilling and Managed Pressure Cementing Offshore Malaysia

Abstract

TA is an over-pressurized well in the field development project located Offshore Peninsular Malaysia. Although the well was drilled as a development well, it also had an exploration objective as it was the first to penetrate the over pressured zones across a fault in the TA field. An initial attempt to drill conventionally resulted in severe gain and loss scenarios across the first of three sands 80 m below the 7" casing shoe, primarily due to weak coal formations. After many attempts to control losses, it was decided to plug-abandon the 6" open hole and to temporarily suspend the well due to insufficient operating window to drill ahead. After a year of suspension, a new drilling approach using a statically underbalanced mud weight (MW) in combination with an Automated Managed Pressure Drilling (MPD) system was introduced as the best solution for drilling into the well objectives. During the planning stage, different scenarios were analyzed based on the formation fracture gradient (FG) and pore pressure (PP) estimations. MPD plans were designed based on statically underbalanced mud while drilling, running the liner, and during the cementing job. During drilling, Dynamic Flow Checks (DFC) and Dynamic Formation Integrity Tests (DFIT) were performed using the MPD system to identify and confirm operating window. The target total depth was successfully reached with mud weighted within the narrow 0.35 ppg drilling window (17.8–18.1 ppg). Decision was then made to top kill the well at 1200 m-MDDF with 18.30 ppg mud, providing an overbalanced condition of 85 psi. Open hole logging operations were then successfully executed. The well was then displaced to a 16.30 ppg mud prior to performing Managed Pressure Cementing (MPC). This technical paper aims to discuss all of the MPD - MPC challenges faced and best practices developed during both the planning and execution stages of the program.

Experimental investigation of hole cleaning in directional drilling by using nano-enhanced water-based drilling fluids

“…borehole with an outer diameter of the drill string equals to 5.5 in. (Ming et al, 2014). In our scale down process of flow parameters, we considered a dimensionless number (Reynold Number) in the annulus, such that the flow is turbulent, as suggested by other studies for efficient hole cleaning operations (Ming et al, 2014;Loeppke et al, 1992;Kristensen, 2013).…”

“…(Ming et al, 2014). In our scale down process of flow parameters, we considered a dimensionless number (Reynold Number) in the annulus, such that the flow is turbulent, as suggested by other studies for efficient hole cleaning operations (Ming et al, 2014;Loeppke et al, 1992;Kristensen, 2013). This could be achieved with a 30-50% scale-down of the mud weight, while using a 10-hp centrifugal pump that provided flowrates and velocities at the scale down ranges of 80%.…”