Packer (bore)

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The packer is a special annular seal that is used in geological drilling .

Principle and areas of application

Technical drawing (longitudinal section) of a borehole packer based on the stuffing box seal principle, here with a solid rubber U-ring (3) as the actual sealing element. This product is used for functional testing of blowout preventers and other equipment at the wellhead, i.e. H. at the top of the wellbore structure of an oil or gas well.

In the case of groundwater extraction points or hydrocarbon production wells, packers enclose the production string and serve to seal off adjacent sections within the borehole casing . They also fix and center the production string in the borehole lining. Packers are used in particular in the context of completing a deep borehole , in which they seal the permeable ( perforated ) section of the borehole lining in the production zone (e.g. in the area of ​​an oil or gas reservoir) against the impermeable part of the pipe section above the production zone.

The most important component of a packer is a more or less long, more or less thick-walled hollow cylindrical element made of elastic, rubber-like material. The sealing effect is technically implemented in two different ways:

  • A thick-walled “hose” or sealing ring is compressed along its longitudinal axis by means of a mechanism, so that the material is arched transversely to the longitudinal axis and pressed against the borehole lining (see →  stuffing box seal ).
  • A thin-walled “hose” is “pumped up” with compressed air or a hydraulic fluid and thus closes the annular space ( inflatable packer ).

Analogous to production wells, packers are used in injection wells, where they ensure that the injection pressure is maintained in the borehole and prevent the grout from rising in the borehole or even emerging from the upper end of the borehole, the borehole mouth. This applies, in principle, both for building injections as well as for fluid injections within the unconventional hydrocarbon production ( hydraulic fracturing ), or the pressing of waste water in the deep underground, at least at the latter, as in the conventional hydrocarbon production, in addition preventers are used. When grouting the ground, it depends on the stability of the rock that is drilled through , whether the packer has to be placed directly above the area to be impregnated or directly at the mouth of the borehole.

Special double packer systems are offered for uncased exploratory boreholes . These consist, among other things, of two expandable packers connected by a rod, with the help of which the test interval can be isolated from the rest of the borehole.

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General

  • Packer in the Schlumberger Oilfield Glossary (English)

Individual evidence

  1. ↑ Maksym Dorokhov, Ivan Kostriba, Volodymyr Biletskyi: Experimental research on the sealing ability of borehole packers. Eastern-European Journal of Enterprise Technologies. Vol. 4, No. 8, 2016, pp. 56-68, doi: 10.15587 / 1729-4061.2016.74831 .
  2. ^ Ulrich Smoltczyk: Grundbau-Taschenbuch. 2. Geotechnical procedures. 6th edition. Ernst & Sohn, Berlin 2001, ISBN 3-433-01446-9 , p. 76 f.
  3. ↑ Simon Löw, Roland Wyss (Ed.): Preliminary exploration and prognosis of the base tunnels on the Gotthard and on the Lötschberg. Taylor & Francis Verlag, 1999, ISBN 905-4-10480-5 , p. 217.
  4. ↑ HDDP - Heavy-Duty double packer system. Solexperts AG, Mönchaltorf 2015 (info sheet; PDF ( memento from August 26, 2016 in the Internet Archive ) 1.6 MB).

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