The management of human factor and the utilization of advanced Annular Pressure Monitoring (APM) tool enhanced the performance of Managed Pressure Drilling (MPD) in a highly permeable and narrow margin high pressure (HP)exploration gas wells in the Niger Delta. The pore pressure prognosis (PPP) indicated narrow drilling window in the HP section which necessitated the deployment of MPD for safe project execution.
The MPD mud design entailed drilling with a mud weight that balanced the expected pore pressure prognosis (PPP) and the application of MPD surface back pressure (SBP) to balance the highest PPP case. During the drilling of the first of a three-well-campaign, a kick was taken with pore pressure equivalent to the highest predicted case. The evaluation of the pre-kick Equivalent Static Density (ESD) data indicated that the bottom hole pressure (BHP) was not maintained at the programmed set point unknown to the MPD operator. Transient dips in the BHP below the set point and pore pressure resulted to significant gas influx from the gas reservoir with permeability of 124 - 204mD and reservoir mobility of 112 – 1000mD/cp. Incident causal analysis revealed the contribution of human factor and limitations of conventional APM tool.
This paper details how human factor was effectively managed using procedures and training, and how the advanced APM tool enhanced MPD process optimization in the second deployment resulting in the achievement of BHP values within the range for safe drilling.