skip navigational links Occupational Safety & Health Administration DOL.gov OSHA.gov DOL.gov
www.OSHA.gov
eTools Home : Oil and Gas Well Drilling Viewing / Printing Instructions | Credits
Oil and Gas Well Drilling and Servicing eTool
 
Job Safety Analysis (JSA)
Site Preparation >> Conductor Hole, Rathole, and Mousehole

Prior to commencing the rig-up process, the conductor, rathole and mousehole are completed.

Special companies may be hired to begin drilling these three holes.
Fig. 1. Conductor hole
Fig. 1. Conductor hole

Back to TopConductor Hole and Conductor Pipe
Fig. 2. Installing conductor hole casing
Fig. 2. Installing conductor hole casing


This is a large diameter hole, lined with pipe, also called a starter hole, varies in depth down of tens of feet to a few hundred feet depending on the local geology.

Some sites do not require a conductor hole.


Potential Hazard:
  • Being struck by hoisting line or suspended drill or casing.
Possible Solutions:


Back to Top Rathole
Fig. 3. Rat hole - covered
Fig. 3. Rat hole - covered

A rathole is a hole in the rig floor, 30 to 35 feet deep, lined with casing that projects above the floor, into which the kelly is placed when hoisting operations are in progress.

This is either done by the portable rig that drills the conductor hole or can be done by the primary rig after rigging-up.


Potential Hazard:
  • Falling or stepping into an uncovered rathole.
Possible Solution:
  • Cover the hole until it is lined with casing or other material during rigging-up.


Back to Top Mousehole
Fig. 4. Mousehole - covered
Fig. 4. Mousehole - covered

A mousehole is a shallow bore hole under the rig floor, usually lined with pipe, in which joints of drill pipe are temporarily placed.

This is either done by the portable rig that drills the conductor hole or can be done by the drilling rig after rigging-up.


Potential Hazard:
  • Falling or stepping into an uncovered mousehole.
Possible Solution:
  • Cover the hole until it is lined with casing or other material during rigging-up.




Site Preparation | Drilling | Well Completion | Servicing | Plug and Abandon Well
General Safety | Additional ReferencesJSA Site Map | Illustrated Glossary | Glossary of Terms

eTools Home : Oil and Gas Well Drilling Viewing / Printing Instructions | Credits
 
Back to TopBack to Top www.osha.gov www.dol.gov

Contact Us | Freedom of Information Act | Customer Survey
Privacy and Security Statement | Disclaimers
Occupational Safety & Health Administration
200 Constitution Avenue, NW
Washington, DC 20210
Page last updated: 01/06/2009