Complex Operation for the Rehabilitation of a Geothermal Well
Successful side-track and re-entry below fish for the rehabilitation of an old geothermal well
Project type:

Industrial Application

Project Location:

Thiais, Paris area, France

Project Leader:
GeoEnergy Europe Partners:
Non GEE Partners:

PathControl, ENGIE-COFELY, Baker-Hughes (France)

Background & context:

A geothermal well doublet had been operated for over 29 years.
During workover operation, a cement squeeze-flash occurred causing the 3 ½” drill string being stuck in hole. Remedial operations using coiled tubing failed. A plan was proposed by CFG Services and DrillScan:
- to side-track above the fish and re-enter the well below it to properly isolate all aquifers with cement barriers
- to drill another side-track to restore injection to the geothermal reservoir.

Project Summary:

1. Side-tracked in cased-hole above fish
2. Drilled new hole along parent well using magnetic ranging relative positioning
3. Soft-touched parent well casing below fish
4. Milled re-entry window into casing
5. Re-entered parent well with a cement stinger
6. Set cement plugs to P&A and isolate aquifers below the fish
7. Side-tracked in open-hole off a cement plug
8. Drilled final geological side-track branch
9. Restored production

Project achievements & innovative aspects:

- Rehabilitation of a Geothermal Well using world class technology
- Aquifers properly isolated with cement barriers and well integrity regained

Innovative aspects:
- Use of unique survey management models
- Use of advanced directional drilling software
- Use of world class magnetic ranging technology

Project Funding:
October 2016 to February 2017
Project Budget: