http://jase.tku.edu.tw/articles/jase-202404-27-4-0006

Abstract

High pressure, narrow mud window and well control risks are common challenges encountered in High Temperature High Pressure (HTHP) wells. Reducing the complexity of incidents and ensuring the safety while drilling in high pressure and narrow mud window wells are technical challenges which need to be urgently solved. Managed Pressure Drilling (MPD) effectively solves the challenges of safety drilling under narrow safe pressure margin by establishing a trapped pressure environment to control the annular pressure profile. However, the risk of down hole pressure fluctuation still exists due to the switch of circulation from downhole circulation to surface circulation during connection in MPD mode. Continuous Circulation System (CCS) is usually used to maintain the full cycle circulation during connection, but the system is also not able to precisely predict the formation pressure and immediately adjust the bottom hole pressure. In this research, the MPD technology combined with the Eni circulating device (e-cdTM) system is presented to overcome the shortages of MPD and CCS technologies when they are individually applied in high temperature high pressure wells. The application of this combined practice in the Obiafu-X well located in Block OML-61, Delta, Nigeria enabled to avoid the occurrence of various non-production time accidents and improved the drilling efficiency. The combination of MPD technology with e-cdTM system in HTHP wells can therefore provide an advantageous reference in the domestic HTHP drilling industry.

Keywords

• wellbore instabilities
• high temperature high pressure
• managed pressure drilling
• continuous circulation system