Nipple (Landing Nipple): Definition, Types, and Completion Use

What Is a Nipple?

A nipple, formally called a landing nipple, is a short, heavy-wall steel sub machined into a production tubing string during completion to provide a polished sealbore and a locking profile. Wireline-deployed or coiled tubing-deployed tools lock into this profile, enabling operators to install and retrieve downhole devices without pulling the full tubing string.

How a Nipple Works

The nipple is threaded into the production tubing string at predetermined depths during the completion design phase. Its internal bore is machined and honed to a tight dimensional tolerance, typically within ±0.002 inches (±0.05 mm), creating a polished sealbore that a matching elastomeric or metal seal assembly on a locking mandrel will engage. Above the sealbore, the bore is machined with a locking groove, a circumferential channel into which spring-loaded collet fingers or lock dogs on the locking mandrel snap when the mandrel is rotated or set. Once engaged, the locked mandrel cannot be moved upward or downward without using the correct wireline running and pulling tools.

The no-go nipple incorporates an additional feature: a reduced-diameter no-go shoulder below the sealbore. This shoulder physically stops any tool with an outer diameter equal to or larger than the no-go ID from traveling below that point. The operator designs the completion so that the largest-OD wireline tool runs to the shallowest nipple that accommodates it, while smaller tools can pass through to deeper nipples. A selective nipple lacks the no-go shoulder, meaning tools can pass through freely until a selective locking mandrel is mechanically activated at the correct depth using a wireline locating collar count or gamma-ray depth correlation. This allows multiple selective nipples of the same size to be stacked in a single string and accessed independently, which is especially useful in multi-zone completions on the same tubing string.

Nipple spacing along the tubing string follows engineering guidelines to maintain a minimum vertical distance between adjacent nipples, typically 2 to 4 metres (6.5 to 13 ft), so that the body of one locked tool does not interfere with the tool below. When a subsurface safety valve is the primary device installed in the shallowest nipple, API Standard 11D1 governs the safety valve type, the sealbore geometry, and the pressure rating. The nipple also has a maximum pressure rating, expressed in psi or MPa, that must exceed the anticipated wellbore pressure under shut-in conditions and the maximum differential pressure the sealed plug will see during production.

Nipple Across International Jurisdictions

Canada (Alberta and British Columbia): The Alberta Energy Regulator (AER) governs subsurface safety valves under Directive 036, which mandates the installation of a surface-controlled subsurface safety valve (SCSSV) in all oil sands and deep sour-gas wells above a specified H2S partial pressure threshold. The nipple that houses the safety valve must be set within 100 metres (328 ft) of the surface, measured along the wellbore, placing a hard engineering constraint on the tubing string design. Montney tight-gas completions in northeast British Columbia routinely incorporate multiple selective nipples to allow blanking plugs to be set for zone isolation without milling out perforations. The BC Energy Regulator (BCER) references API 11D1 for safety valve qualification in its Well Authorization Manual.

United States (Offshore and Onshore): The Bureau of Safety and Environmental Enforcement (BSEE) regulates offshore subsurface safety valves under 30 CFR Part 250, Subpart H. The regulation requires a SCSSV or storm choke in every offshore production well, with the valve set at or below the ocean floor but no deeper than 100 ft (30 m) below the mudline on most platforms. The nipple housing the valve must be rated for the maximum anticipated shut-in tubing pressure (SITP), and the operator must document the nipple design, profile type, setting depth, and pressure rating in the well's Safety and Environmental Management System (SEMS) file. Onshore unconventional wells in Texas and North Dakota typically use nipple designs per API 11D1 with no regulatory mandate for safety valves unless H2S exceeds threshold concentrations under EPA and OSHA rules.

Norway and the North Sea: NORSOK Standard D-010, "Well Integrity in Drilling and Well Operations," classifies a properly seated subsurface safety valve as a well barrier element (WBE). The nipple that accepts the safety valve is itself a critical component of the primary well barrier, and its design, material certification, and inspection records must be documented in the well barrier schematic submitted to the Petroleum Safety Authority Norway (PSA). NORSOK D-010 requires that each WBE be tested to demonstrate pressure integrity at installation. The Norwegian Continental Shelf (NCS) also requires dual barrier philosophy in HPHT wells, sometimes necessitating a second safety valve in a deeper nipple as the secondary barrier element.

Australia: The National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) requires surface-controlled subsurface safety valves in all offshore production wells under the Offshore Petroleum and Greenhouse Gas Storage (Safety) Regulations. NOPSEMA's Well Operations Management Plan (WOMP) framework requires operators to document nipple profile type, setting depth, maximum allowable working pressure (MAWP), and testing intervals. Browse Basin and Carnarvon Basin high-pressure gas wells use nipples manufactured to API 11D1 with supplemental material qualifications for high-CO2 service, as Gorgon and Ichthys reservoir gases contain CO2 concentrations between 3% and 14%.

Middle East: Saudi Aramco Engineering Standards (SAES-E-201 and SAES-E-402) specify nipple profile geometry, material grades, and SSSV qualification requirements for Ghawar, Shaybah, and offshore Safaniya field completions. Saudi Aramco requires the nipple and any installed safety valve to pass a function test and pressure test witnessed by an Aramco representative before the well is handed over to production operations. Some offshore wells in the Arabian Gulf with elevated H2S require dual SCSSV installations, with the upper valve in a no-go nipple providing depth assurance and the lower valve in a selective nipple providing redundancy.