Looking Ahead of the Bit While Drilling: From Vision to Reality
- Monica Vik Constable (Statoil ASA) | Frank Antonsen (Statoil ASA) | Stein Ottar Stalheim (Statoil ASA) | Per Atle Olsen (Statoil ASA) | Oystein Zahl Fjell (Statoil ASA) | Nick Dray (Statoil ASA) | Sigurd Eikenes (Statoil ASA) | Haakon Aarflot (Statoil ASA) | Kjetil Haldorsen (Statoil ASA) | Gunnar Digranes (Statoil ASA) | Jean Seydoux (Schlumberger) | Dzevat Omeragic (Schlumberger) | Michael Thiel (Schlumberger) | Andrei Davydychev (Schlumberger) | Jean-Michel Denichou (Schlumberger) | Diogo Salim (Schlumberger) | Mark Frey (Schlumberger) | Dean Homan (Schlumberger) | Sarwa Tan (Schlumberger)
- Document ID
- Society of Petrophysicists and Well-Log Analysts
- Publication Date
- October 2016
- Document Type
- Journal Paper
- 426 - 446
- 2016. Society of Petrophysicists & Well Log Analysts
- 7 in the last 30 days
- 406 since 2007
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A vision in the oil industry for decades is becoming a reality. Finally, we are able to drill and react proactively to formation resistivity properties several meters ahead of the drill bit, instead of reacting to measurements behind the bit. Through a technology collaboration between operating and service companies, a targeted technology development for measuring resistivity contrasts ahead of the bit in real time to reduce cost and risk during drilling operations was developed. Two electromagnetic look-ahead (EMLA) prototypes have been developed for 12¼- to 14-in. boreholes. The EMLA tool is modular and consists of a low-frequency transmitter inserted in the rotary steerable drilling assembly 1.8 m behind the bit and two to three receivers spaced out in the drillstring. The EMLA tool uses the same sensor technology and operates with the same multispacing and multifrequency measurements as the commercial ultradeep “look-around” directional resistivity tool. The formation structure ahead of the bit is interpreted by inversion to differentiate sensitivity around the tool from effects ahead of the bit. The look-ahead capability is dependent on the transmitter-receiver spacing, frequency, resistivity around the tool, thickness of the target, and the resistivity contrast ahead of the bit.
The EMLA tool provides a step change with regard to precision in detecting changes in resistivity properties ahead of the bit in vertical and low-angle wells. The ability to react to resistivity contrasts ahead of the bit has a direct impact on how wells are drilled. The main application of EMLA to date has been to drill the well section above the reservoir closer to top of reservoir to avoid complications in the shale above the reservoir, as presented in two case studies. Challenges related to salt drilling are addressed in another case study where the salt exit was detected 30 m ahead of the bit. Improved precision in coring-point selection is another potential application.
|File Size||54 MB||Number of Pages||21|