Every drilling and workover campaign eventually faces the same moment: something in the hole won’t come out. Stuck pipe. A parted string. A lost tool. How fast it comes back out — and whether it comes out at all — is decided long before the fishing tools run, by the quality of the selection made on surface.
The bad news: a wrong tool selection is worse than no attempt. An overshot run for a spear job, or a grapple matched to the wrong casing weight, can push the fish deeper or damage the wellbore. The good news: fishing tool selection follows a repeatable, methodical process. This guide walks through it — from diagnosing the fish to matching the tool to the catch.
Step 0: Diagnose Before You Run
Fishing is diagnosis first, hardware second. Before any tool is selected, you need to know:
- What is the fish? Pipe, drill collar, tool, debris — and its exact size and profile
- Where is it? Current depth, and whether it’s free or stuck
- What’s around it? Casing size and weight (for clearance and catch matching), wellbore condition, any debris on top of the fish
- What’s the objective? Recover the fish, mill it, wash over it, or sidetrack around it
Skipping this step is the single most common cause of failed fishing jobs. If you’re uncertain about the fish top, run an impression block first — one survey run that records the fish’s shape replaces guesswork and saves trips.
The Tool Family, and When Each One Earns Its Place
Heverda supplies the full recovery tool range. Here’s the selection logic for each family:
Spears (releasing) — engage the fish from inside its bore.
– Use when: the fish has an accessible internal bore and you need a controlled, releasable grip
– Why it matters: the ability to release and re-engage turns a one-shot gamble into a controlled operation
Overshots — engage the fish from the outside.
– Use when: the fish bore is blocked, collapsed or inaccessible, and the OD is accessible
– Why it matters: the workhorse of recovery — most pipe and tool-joint recovery starts with an overshot
Grapples / slips — the gripping elements for spears and overshots.
– The rule that decides fishing jobs: one catch size = one part number. Each grapple is matched to a precise casing weight and ID. A 0.1–0.2″ ID difference between adjacent casing weights means a wrong grapple either slips or refuses to engage.
Jars — deliver controlled impact loads to break a stuck fish free.
– Use when: pull alone won’t free the fish after engagement
– Why it matters: correct jarring force at the right moment is often the difference between a two-hour job and a two-day one
Mills — dress, cut or grind the fish and debris.
– Use when: the fish needs a clean profile before recovery, or is junk to be milled in place
– Why it matters: a dressed fish is a recoverable fish
Die collars — recover smooth fish by external die-cutting engagement.
– Use when: the fish is smooth with no gripping points
Impression blocks — the survey tool. Run one before selecting the recovery tool.
Circulating subs — establish circulation above the fish for washover and debris cleanout.
Overshot vs. Spear vs. Jar: The Decision Rule
The three most-confused choices in fishing tool selection:
| Question | Answer |
|---|---|
| Can you get at the fish’s outside? | Overshot (with correct grapple) |
| Can you get at the fish’s inside? | Releasing spear |
| Is the fish stuck and pull won’t free it? | Add a jar to the string after engagement |
The jar is not a replacement for the overshot or spear — it’s an addition. The typical recovery string is: overshot or spear + jar + safety release. Selecting the gripping tool and the impact tool are separate decisions.
The Catch Size Trap (and Why Precision Wins)
Fishing tools live and die by catch-size precision. Consider 7″ casing:
| Casing Weight (lb/ft) | ID (in) | Correct Catch Size Range (in) |
|---|---|---|
| 7″ 22# | 6.398 | 6.350 – 6.398 |
| 7″ 26# | 6.276 | 6.220 – 6.276 |
| 7″ 29# | 6.184 | 6.130 – 6.184 |
| 7″ 32# | 6.094 | 6.050 – 6.094 |
| 7″ 38# | 5.920 | 5.870 – 5.920 |
A grapple matched to 7″ 26# does not work on 7″ 29# — the ID difference is under a tenth of an inch, and that’s exactly the point. The tool has to grip that fish exactly, or it slips under load and the fish is lost deeper.
This is why Heverda dimensionally verifies every catch size with a CMM (Coordinate Measuring Machine) and reports results per part, and maintains a precise catch-size ↔ part-number mapping across the spear and grapple range. A PO quoting the casing weight is unambiguous; the field engagement is predictable.
Documentation: The Part Operators Underestimate
The quality file package is not paperwork — it’s what lets the drilling engineer run recovery tools with confidence:
- Dimensional verification — catch sizes and critical dimensions, CMM-reported per part
- Material certification — EN 10204 3.1 certificate with alloy grade, HRC hardness and heat-treatment status
- Lot traceability — each part laser-marked with a lot number
- Batch sample test report — dimensional, material and visual inspection summary per shipment
- Third-party inspection — SGS / BV or nominated inspection on request
If a supplier can’t document the catch size before shipment, they’re asking you to discover it in the hole.
The Selection Inputs to Prepare
To configure the right tool, your supplier needs four things:
- Fish type & size (pipe / collar / tool / debris) and current wellbore depth
- Casing program (size, weight, ID — for catch matching)
- Operation objective (recover / washover / mill / sidetrack)
- Required documentation (EN 10204 3.1, third-party inspection, export documents)
Conclusion
Fishing tool selection is methodical, not magical: diagnose the fish, choose inside vs. outside engagement, match the catch size exactly, add a jar if it’s stuck, and verify the documentation before you run. Suppliers who treat catch size as precision engineering — verified, documented and traceable — are the ones whose tools come back out of the hole with the fish.
Tell us your fish type, casing program and operation objective, and we’ll confirm the tool, catch size and documentation package before you order.
Fishing Tool Selection Guide | Overshot vs Spear vs Jar
How to choose the right fishing tool — overshot, spear, or jar — for stuck pipe recovery, matched to the fish, the wellbore, and the rig.
Heverda Drilling Tools — Shenzhen Hexinhe Technology Co., Ltd. ｜ sales@heverda.com ｜ www.heverda.com