Non-Productive Time Reduction In Overpressured Reservoirs Through Seamless Integration of MPD, LWD And RSS Technologies.

Abstract

This case study shows a cooperative implementation of managed pressure drilling (MPD), logging while drilling (LWD) and rotary steerable system (RSS) technologies to prevent non-productive time (NPT) while drilling through a section with a tight pressure window in a highly over-pressured reservoir in the US. Drilling risks were proactively reduced by providing real time data transmission for reservoir characterization and identification of critical well sections. The bottom hole assembly (BHA) was designed to be able to provide high quality measurements according with specific priorities in real time formation characterization and post mortem evaluation. The data transmission was also optimized to be able to monitor the performance of the rotary steerable system (RSS) as well as provide logging measurements that allowed decision making in real time. The implementation of MPD and the continuous monitoring of pressure while drilling (PWD) data allowed to adjust the downhole pressure profile to minimize the impact of drilling hazards by early detecting micro influxes and micro losses reducing considerably their size and impact to control them. Acquisition and transmission of high-quality logging while drilling data in real time allowed to identify the formations being drilled using Gamma Ray and resistivity logs anticipating the risk associated with each formation. The accurate identification of the pore pressure ramp, a consequence of using real-time MWD GR logging to correlate incoming formation tops with offset data, and the monitoring of the PWD data help to proactively respond to the imminent drilling hazards allowed to drill through these problematic sections using an underbalanced mud weight with the help of MPD which can adjust the pressure profile immediately reducing the risk of NPT. In addition to LWD and MPD technologies, the implementation and monitoring of RSS reduced the risk of downhole mechanical problems. Furthermore, acquired high-resolution sonic and density data from memory provided means to tie together the seismic data, in time, and LWD data, in depth, in order to make accurate predictions of incoming formations tops for future wells. This improved predictive capability to identify the depth range of the pore pressure ramp, while the correlative in-formation log signatures provided robust analysis of offset producing trends. Drilling scenarios that otherwise deemed unattainable due to the big potential for drilling hazards, can currently be tackled safely while also optimizing capital expenditure through the implementation and monitoring of reliable LWD, MPD and RSS systems. The designed BHA allowed reliable data acquisition and the use of MPD enabled the versatility of instantaneously adjusting the downhole pressure profile leading to a flawless drilling operation with reduced NPT associated to pressure-related issues.