Innovative Expandable Under Reamer Technology in Combination with Wired Drill Pipe Technology
Authors: Grymalyuk S. , Schimanski M. , Lilledal L. 
Published: November 2016

This paper presents and discusses the results of a series of field applications where innovative, expandable under reamer technology in combination with wired drill pipe (WDP) technology was implemented by Total E&P Norge on the Martin Linge field development project in the Norwegian sector of the North Sea.

Martin Linge's resources comprise an oil reservoir and several, deeper, structurally complex, high-pressure gas and condensate reservoirs. The oil reservoir is developed with long horizontal wells and several deviated wells will be drilled to unlock the deeper gas and condensate reserves. The field was initially discovered in 1975 but proved too complex to develop at the time.

Over the years, several exploration and appraisal wells were drilled within a narrow pressure window, with multiple BHA runs per section. The complex drilling environment posed many challenges, including severe mud losses, unstable formations (borehole collapse) and excessive downhole shock and vibrations resulting in poor MWD/LWD signal and tool failures.

The rig utilized to drill the Martin Linge field is equipped with Wired Drill Pipe (WDP) telemetry. This is a drillpipe which enables bi-directional, low-latency, high-speed data transmission. Conventional telemetry methods only provide very limited bandwidth for real-time data transmission and can suffer from signal reliability problems under adverse conditions; for example: no mud pulse data transmission during pump-off or at low flow rates, decoding issues during high levels of downhole shock and vibrations and unfavorable mud conditions.

The on-command digital, expandable under reamer is fully integrated into the bottomhole assembly (BHA) and can be monitored and controlled from the surface. The real-time feedback from the reamer includes tool vibration and stick slip (VSS) data, and confirmation of blade activation status and blade position (being fully retracted, fully extended, or transiting between the fully retracted and fully extended position). The extended blade position is pre-configured to a certain postion on surface and the reamer will open up to this position when activated, afterwhich reaming operations will begin. The real-time feedback reduces operational uncertainty during reaming and saves time for a shoulder test. Unlimited activation cycles provide the capability of selective reaming. The flexible placement of multiple reamers in the BHA enables near-bit and main reaming applications, and a combination of both. When used for near-bit reaming service, the reamer can reduce the rat-hole length to 4 m, compared to an application where it is placed 40 to 70 meters behind the bit. Significant time savings can be achieved by eliminating the dedicated rat-hole run.

The combination with WDP boosts the advantages of this innovative under reaming technology. The short activation time is reduced further compared to conventional downlink and mud-pulse telemetry, providing significant time savings. The low latency of the high-speed communication to the reamer enables on-time decisions during complex drilling and reaming applications.

This paper summarizes the resulting efficiency gains and quantified time savings achieved by the combination of innovative under reaming and WDP technologies. This combination enables wells to be drilled without the typical limitations imposed by conventional reaming and telemetry methods.