When drilling or workover operations encounter a stuck or lost object in the wellbore, specialized retrieval equipment becomes the only solution. Oil & Gas Fishing tools are designed to latch onto, cut, mill, or recover debris ranging from broken drill pipe to dropped tools and stuck logging equipment. The Oil & Gas Fishing Market has seen continuous innovation in tool design, with advanced materials and hydraulic enhancements improving success rates. For drilling engineers, well intervention specialists, and tool pushers, understanding the capabilities and limitations of different fishing tools is essential for selecting the right approach and minimizing costly non-productive time (NPT). This guide provides a detailed overview of primary fishing tool categories, their operating principles, and application guidelines.

Internal and External Catch Tools
The most common fishing tools are those that grasp the fish (stuck object) by its internal diameter (ID) or external diameter (OD). Selection depends on whether the fish has a accessible bore or a smooth outer surface.

• Overshot: The workhorse for external catch. An overshot is a cylindrical tool that slips over the outside of the fish. It contains a spiral grapple (helically segmented steel basket) that contracts around the fish when weight is set down. The grapple’s teeth bite into the fish, providing a secure grip. Overshots are available for pipe sizes from 1” to 20” OD. Key advantage: can engage fish with irregular or damaged surfaces. The Oil & Gas Fishing tools family includes both “bowl-type” (standard) and “releasing” overshots (which can disengage if the fish cannot be pulled free). Modern overshots incorporate a milled tooth grapple for hard fish (e.g., alloy steel) and a sharp tooth for softer fish (e.g., aluminum).

• Spear (Internal Catch): Designed to enter the fish’s internal bore and grip outward. A spear has a tapered mandrel and a grapple that expands outward when set down. Used for fishing drill pipe, casing, or tubing where the ID is accessible. Spears are available for fish IDs from 1” to 12”. A “basket grapple” spear is for standard pipe; a “straight grapple” spear is for irregular or damaged IDs. For shallow engagement, a “pull spear” with a hooked grapple is used.

• Die Collar / Taper Tap: For fish with damaged or no threaded connection. A die collar has hardened steel “teeth” on its internal surface. It is rotated over the fish, cutting a new thread profile, then pulled. This is a one-way tool—once engaged, it cannot be released without unscrewing. Used as a last resort before milling.
  Successful fishing begins with accurate fish dimension measurement (caliper log or impression block). A poor grip choice leads to lost time and potentially losing the fish deeper.

Impact and Jarring Tools
Often, the fish is stuck due to differential pressure sticking, keyseating, or wellbore collapse. The fish will not pull free with steady tension; impact force is required.

• Drilling Jars: Hydraulic or mechanical tools that store energy and release it suddenly, delivering a high-impact upward or downward blow to the fish. Hydraulic jars (e.g., Bowen, Dailey) are most common. They have a metering valve that delays release until a certain overpull is reached, then slams shut, delivering an impact of 50,000-500,000 lbs. Drilling jars are run as part of the fishing string, above the overshot or spear.

• Bumper Subs (Accelerators): Placed above the jar to increase impact by storing energy in a spring or compressed nitrogen chamber. The accelerator adds 30-50% more impact force, useful for deep, deviated wells where friction dampens jarring action.

• Jar Intensifiers: Used when the fishing string is stuck as well; the intensifier delivers a jarring action from the stuck point upward, rather than from surface.
  Proper jar placement is critical: the jar should be positioned just above the fish (30-50 feet) to concentrate impact. Jarring should follow a systematic sequence (e.g., increasing overpull by 20,000 lbs per attempt). The Oil & Gas Fishing tools market offers “double-acting” jars that deliver both up and down blows—essential for cocked or wedged fish.

Milling and Cutting Tools
When grasping the fish is impossible (e.g., debris is too fragmented or the fish is cemented in place), the alternative is to mill or cut it, then fish the pieces.

• Junk Mill: A flat-bottomed or tapered mill with crushed tungsten carbide inserts. Rotated at moderate speed (80-120 RPM) with weight (5,000-15,000 lbs), it grinds junk into small pieces that can be circulated out or caught with a magnet or junk basket. Junk mills are available from 3” to 12” diameter. For hard debris (e.g., carbide buttons, roller cone fragments), a “tough cut” mill with larger, more robust carbide inserts is used.

• Section Mill: A longer mill (up to 20 feet) used to grind away an entire section of stuck casing or pipe, rather than retrieving it. Section milling is a last resort because it creates a large volume of metal chips and weakens the surrounding wellbore.

• Chemical Cutters and Jet Cutters: Use shaped charges or reactive chemicals to sever pipe at a specific depth. Jet cutters (explosive) produce a clean cut but require careful depth control to avoid damaging casing. Chemical cutters (e.g., high-pressure fluorine) are slower but safer in sensitive environments.

• Diamond Wire Cutting: Used for very large or hard fish (e.g., BOP stack, heavy subsea equipment). A diamond-impregnated wire is wrapped around the fish and tensioned, cutting over hours.
  Milling operations require constant circulation to remove cuttings and cool the mill. Monitor torque and standpipe pressure for signs of balling (cuttings packing around the mill). The Oil & Gas Fishing tools market now includes “under-reaming” mills that can expand a milled window without tripping out.

Debris Retrieval and Junk Baskets
After milling, or when loose junk is present, debris retrieval tools clean the hole.

• Junk Basket (Magnet): A strong permanent magnet (neodymium or samarium-cobalt) encased in a steel body. Lowered past junk, then raised; magnetic debris sticks to the basket. For non-magnetic debris (e.g., aluminum, brass), a “reverse circulation junk basket” uses flow to suck debris into a catcher.

• Boot Jack Baskets / Fishing Baskets: A cylindrical basket with spring-loaded fingers or flapper valves that allow junk to enter but not exit. Rotated and reciprocated to “sweep” the hole.

• Hydrostatic Junk Catcher: Uses differential pressure to pull debris into a chamber; triggers on contact with the bottom.
  A clean wellbore before fishing dramatically improves success rates. The Oil & Gas Fishing operation procedure typically includes a “clean-out run” with magnet and basket before attempting internal catch.

Tool Care and Inspection
Fishing tools are expensive (overshots $10,000-$50,000, jars $30,000-$100,000) and safety-critical. Oil & Gas Fishing tools require:

• Magnetic particle inspection (MPI) or dye penetrant after each use, focusing on threads, grapple teeth, and jar connections. Cracks grow rapidly under the high shock loads of jarring.

• Thread compound (API modified) with high zinc content to prevent galling under extreme pressure.

• Storage in dry, heated containers to prevent rust. Grapples should be removed, cleaned, oiled, and stored separately.

• Function testing jars on a test stand every 6 months or after severe use (e.g., >100 jarring cycles).
  By understanding the full range of oil & gas fishing tools—from overshots to jars to junk mills—well intervention teams can significantly reduce the cost and time of downhole recovery. The right tool, correctly applied, can turn a potential well abandonment into a minor repair.

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