Making the Impossible Possible with MPD Application on 0.4 ppg Mud Weight Window – A Case History Successful Automated Managed Pressure Drilling, Managed Pressure Run 11 3 4” Liner 9 5 8”Liner (Tieback Liner), and Managed Pressure Cementing in a Semisubmersible Offshore Sarawak Malaysia

摘要

The JST-1 well is an offshore High Pressure and High Temperature (high pressure by gradient which was more than 0.1 psi/ft) exploratory well, located in the block SK 301A. The primary objective was to evaluate the hydrocarbon potential in Cycle VII and Cycle VI, at the depth of 2374 and 2794 mTVDDF respectively with anticipated reservoir pressure of 5476 and 6898 psi with temperatures from 226 to 264 °F at well TD 3477mMDDF/TVDDF the pressure and temperature was predicted to be 9276 psi and 302 °F. The well was initially planned to be drilled to 2979 mTVDDF in 12 ” hole section and 8 ” hole section until 3477 mTVDDF. The degree of uncertainty in JST-1 pore pressure and fracture gradient estimates are highly uncertain. This was due to the reason that the offset wells, S-1 and L-1 are very far away from JST-1, approximately 33 km away to the North West and 35 km to the North East respectively. In addition, none of the offset wells have been drilled deeper than 2879 mMDDF. Therefore, high case pore pressure and fracture gradient estimates were used for the well design and planning. Based on cementing simulation for the 11 ” liner, 9 5 8” casing cementing jobs, the resultant cement slurry Equivalent Circulating Density (ECD) will fracture the formation while the cement is pumped into the open hole. Hence, the Managed Pressure Drilling (MPD) method was used to drill hole sections lower than 13 3 8” casing as well during the cementing job and running in hole with 9 5 8” casing. This paper aims to describe the application of Automated MPD on this specific well from conceptual to planning to finally execution. Moreover, with the intention to share the challenges observed during execution as well as the decisions taken to overcome these challenges and finally the 5 steps strategy to ensure the well was stable.