Fishing Tool: Definition, Types, and Downhole Recovery Operations

What Is a Fishing Tool?

A fishing tool is a specialized downhole device run on drillpipe or wireline to locate, grip, and retrieve equipment that becomes lost or stuck inside a wellbore. Operators deploy fishing tools across every drilling environment, from shallow onshore wells in Alberta's Montney formation to deepwater Gulf of Mexico and Norwegian North Sea high-pressure, high-temperature (HP/HT) wells.

How a Fishing Tool Works

Fishing operations begin with a diagnostic phase. The driller and company man review the drillstring inventory to determine what is in the hole, its outer diameter (OD) and inner diameter (ID), and its approximate depth. An impression block, a short steel sub fitted with a lead or soft-alloy face, is run to the fish top, pressed firmly against it, and retrieved. The lead face retains a negative impression of the fish profile, confirming whether the top is clean and centered, off-center, or collapsed. In modern wells, downhole cameras and ultrasonic imaging tools can supplement or replace the impression block, providing video feed or acoustic cross-sections that identify the fish condition and help the engineer select the correct grappling tool.

Once the fish geometry is confirmed, the fishing engineer selects from the tool classes described below. Inside grappling devices such as spears enter the fish bore, expand, and latch onto the internal profile. Outside grappling devices called overshots slip over the outside of the fish and contract to grip its OD. Both are connected to a string of drill collars and drillpipe that transmits the mechanical load to surface. If straight overpull cannot free the fish, a jar assembly is added to the string. Hydraulic jars or mechanical jars deliver high-impact upward or downward blows measured in thousands of pounds-force. Hydraulic jars, for example, typically require a trip load of 20,000 to 50,000 lbf (89 to 222 kN) above normal string weight before the jar fires, delivering a short-duration impact force that can reach several hundred thousand pounds-force at the fish. Accelerators, also called bumper subs, are placed above the jar to add stored elastic energy to each stroke, increasing impact severity.

When mechanical recovery fails after multiple jar runs, the engineer may order a washover operation. Washover pipe is a large-OD, thin-wall tubular run over the outside of the fish. A rotary shoe or mill at the bottom of the washover string grinds through any cement, debris, or formation that has packed around the fish, freeing it for subsequent grapple recovery. If the fish cannot be recovered at all, milling destroys it in place, grinding it into fine cuttings circulated to surface with drilling fluid. Milling is the last resort because it is slow, consuming expensive rig time, and may leave small fragments that complicate later completion operations.

Fishing Tool Across International Jurisdictions

Canada: Alberta Energy Regulator and Prairie Provinces

In Alberta, the Alberta Energy Regulator (AER) governs lost-in-hole reporting under Directive 059 (Well Drilling and Completion Data Filing Requirements) and Directive 008 (Surface Casing Depth Requirements). Operators must report any equipment lost in the wellbore as part of their well completion or abandonment report. The AER requires that metallic debris in a wellbore not impair long-term zone isolation, meaning the licensee must demonstrate either successful recovery or adequate cement plug placement over the fish before the well is approved for abandonment. In the Montney play of northeast British Columbia and northwest Alberta, pad drilling with dozens of wells per surface location means a fishing incident on one well can delay the entire pad schedule, amplifying the economic urgency of fast recovery decisions. British Columbia's Oil and Gas Commission (OGC, now the Energy Regulator) follows analogous reporting requirements under the Drilling and Production Regulation.

United States: BSEE Offshore and State Regulators Onshore

The Bureau of Safety and Environmental Enforcement (BSEE) regulates offshore fishing operations on the US Outer Continental Shelf. Under 30 CFR Part 250, operators must report any wellbore incident, including lost tools, to the district manager within specific time windows. BSEE Notices to Lessees (NTLs) provide supplemental guidance on well control during fishing operations, emphasizing that the blowout preventer (BOP) must remain in a tested and operable condition throughout the fishing job. In the deepwater Gulf of Mexico, where a single rig day can cost $500,000 USD or more, the economics of fishing versus sidetracking are evaluated rapidly. Onshore, state oil and gas commissions (Texas Railroad Commission, Colorado OGCC, North Dakota Industrial Commission) require incident reporting at the well completion filing stage.

Australia: NOPSEMA

Australia's National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) requires titleholders operating under the Offshore Petroleum and Greenhouse Gas Storage Act 2006 to maintain a Well Operations Management Plan (WOMP) that explicitly addresses well integrity during fishing operations. Any event that affects well integrity, including a fish left in hole that prevents proper zonal isolation, triggers a mandatory notification to NOPSEMA. NOPSEMA inspectors audit WOMPs for adequacy of contingency procedures, which must include fishing and milling plans for the most common failure scenarios on each well type.

Norway: Sodir

The Norwegian Offshore Directorate (Sodir, formerly the Norwegian Petroleum Directorate) and the Petroleum Safety Authority Norway (PTIL) jointly oversee well integrity on the Norwegian Continental Shelf. PTIL's Well Integrity Regulation and the NORSOK D-010 standard (Well Integrity in Drilling and Well Operations) define minimum requirements for the maintenance of well barriers during all drilling phases, including fishing. Under NORSOK D-010, operators must maintain at least one well barrier at all times, meaning that while a fish obstructs the wellbore, the BOP or a retrievable packer below the fish must serve as the primary barrier. Norwegian HP/HT wells in the Barents Sea and in fields such as Kristin and Kvitebjorn involve elevated wellbore temperatures (above 150 degrees Celsius, 302 degrees Fahrenheit) and pressures that make elastomer seal performance in fishing tools critical, often requiring metal-to-metal seal connections rated above 15,000 PSI (1,034 bar).

Middle East: Saudi Aramco and Gulf Operator Standards

In Saudi Arabia, Saudi Aramco's internal well engineering standards (SAES) govern fishing operations on its vast onshore and offshore portfolio. Aramco's deep sour gas wells in fields such as Hawtah and Khuff require corrosion-resistant fishing tool materials, including 13% chromium or duplex stainless steel components, because standard carbon steel spears and overshots degrade rapidly in hydrogen sulfide (H2S) environments. The Abu Dhabi National Energy Company (TAQA) and Abu Dhabi National Oil Company (ADNOC) follow similar protocols on offshore platforms in the Arabian Gulf, with fishing operations coordinated through their respective drilling departments and contracted to service companies under long-term agreements.