Rabbit: Definition, Drift Gauge, and Tubular Clearance
What Is a Rabbit?
A rabbit is a drift gauge run through casing, tubing, drill pipe, valves, or completion equipment to prove the inside diameter is open enough for the next tool. API Spec 5CT casing and tubing practice uses drift testing to verify minimum clearance. In the field, passing the rabbit means the planned path is open.
Key Takeaways
- A rabbit is a go/no-go clearance check, not a detailed measuring tool.
- API Spec 5CT drift practice is the casing and tubing anchor behind many pipe-yard and rig checks.
- The correct gauge depends on pipe size, weight, connection, and the actual tool that must pass.
- Rabbitting catches dents, collapse, scale, cement, ovality, bad connections, and debris before the main job starts.
- A cheap surface hang-up is better than a stuck perforating gun, plug, pump, or logging tool downhole.
How a Rabbit Works
A rabbit is usually a smooth cylindrical gauge with rounded ends. Crews pull it, push it, drop it, or pump it through the equipment path. If it passes, the path has at least the required clearance. If it stops, the joint or interval has to be cleaned, repaired, rejected, or rechecked with the correct gauge.
The test is simple because the failure it prevents is expensive. A pipe joint can look fine from the outside and still have a tight spot inside. A small restriction may not matter until a logging tool, bridge plug, perforating gun, or rod pump tries to pass through it.
Why API Drift Is Not Just Paperwork
API Spec 5CT is the common reference for casing and tubing, including drift concepts. Drift diameter is smaller than nominal inside diameter because real pipe has tolerances, wall-thickness variation, straightness limits, and connection effects. The rabbit proves usable passage, not catalogue optimism.
Field crews use the idea more broadly than pipe manufacturing. They may rabbit a Christmas tree bore, tubing string, valve, landing nipple, completion assembly, or workover path. When clearance is tight, the rabbit should represent the actual tool path, including the restrictions that matter.
How to Read Rabbit in Context
The best way to teach rabbitting is to remember that the well does not care what the drawing says. The drawing says the tool should pass. The rabbit proves whether the actual steel path will let it pass today. That difference matters most in old wells, where years of production, scale, wax, corrosion, and workovers can turn a once-clean bore into a restriction.
Fast Facts
- Nominal inside diameter is not the same as drift diameter.
- Drift is the practical clearance a tool can count on after manufacturing tolerances and connection effects are considered.
- A rabbit proves the actual path today, which matters most in older wells with scale, wax, corrosion, or deformation.
Tip: When the planned tool has tight clearance, rabbit the actual path through valves, nipples, tubing, and completion hardware, not only a sample joint.
Rabbit Synonyms and Related Terminology
Rabbit is also known as:
- drift: common name for the clearance test.
- drift gauge: formal tool name.
- rabbit gauge: field name for the gauge.
Related terms: casing, tubing, production tubing.
Frequently Asked Questions
Why is it called a rabbit?
It is field slang for the gauge sent through the pipe or equipment to prove the passage is open.
What happens if the rabbit does not pass?
The crew investigates the restriction before running the main tool. They may clean, repair, reject, or change the tool plan.
Is rabbitting only for new pipe?
No. It is also used before interventions in older wells where scale, wax, corrosion, or deformation may reduce clearance.
Why Rabbit Matters in Oil and Gas
Rabbit matters because it connects a word to a real decision in the field, the lab, or the interpretation room. A useful definition should make the concept clear enough to act on, technical enough to avoid false confidence, and specific enough that the reader understands what can go wrong. That is the standard for this glossary: plain language first, evidence underneath, and enough operational context that the term feels connected to actual oil and gas work. The article should teach, not merely label. If a reader leaves knowing what to check next, the page has done its job.