Landing Collar

What Is a Landing Collar?

Landing collar (also called a plug-landing collar or cementing collar) is a downhole completion accessory installed in a casing or liner string that receives and seats a wiper plug or cementing plug at the conclusion of a primary cement job. When the plug lands and seats in the collar, a sudden pressure increase at surface, called bump pressure, confirms that the cement slurry has been fully displaced ahead of the plug and that the calculated cement volume has been pumped behind casing, providing positive confirmation that cement placement is complete.

Key Takeaways

The landing collar seats the top plug at the end of a cement job, providing a positive pump-off signal (bump pressure) that tells the crew cement displacement is complete.
The landing collar is distinct from the float collar: the float collar sits one or two joints above the shoe and houses check valves that prevent cement backflow, while the landing collar is placed higher in the string to receive the plug.
A two-plug cementing system uses a bottom wiper plug released ahead of cement to wipe drilling fluid off the casing wall, followed by a top plug that travels behind the cement and seats in the landing collar.
Bump pressure is typically observed as a sudden 200 to 500 psi pressure increase above displacement pressure, confirming plug seating; the operator then holds pressure to verify plug integrity before releasing it.
Multi-stage cementing collars serve a different function: they are opened mechanically or hydraulically to allow cement to be pumped through ports in the casing wall for stage cementing above previously placed cement.

How a Landing Collar Works

In a primary cement job, the casing string is run to the desired setting depth with a float shoe at the bottom and a float collar one to two joints above it. The landing collar is installed higher in the string, its position calculated so that when the top plug seats in it, the correct volume of cement occupies the annulus between casing and formation from the shoe up to the desired top of cement. The collar's internal profile consists of a machined landing seat or a baffle with a restricted bore that catches the nose of the cementing plug when it arrives. The plug body seals against this profile, blocking further fluid flow and causing pump pressure to rise sharply at surface.

The cementing sequence begins by releasing a bottom wiper plug from the cementing head at surface. This plug travels down the casing ahead of the cement slurry, wiping residual drilling fluid from the casing inner wall to prevent contamination of the cement. The bottom plug is designed to rupture when it reaches the float collar, allowing cement to flow through and into the annulus. Cement is then pumped until the calculated volume has been displaced into the annulus. A top plug is released from the cementing head and displaced with drilling fluid or fresh water at the calculated displacement volume. When the top plug seats in the landing collar, displacement stops and bump pressure appears on the gauge. The crew holds this pressure for several minutes to confirm the plug has seated properly and the float valves in the float collar are holding against backflow before releasing pressure and allowing the cement to set.

Landing collars are manufactured from drillable cast iron, aluminum alloy, or engineered composite materials so they can be milled or drilled out after the cement has cured if the wellbore must be opened for production or further drilling. The mechanical strength of the collar must be sufficient to withstand the differential pressure across the seated plug, which can reach 1,000 to 3,000 psi during displacement in deep or high-pressure wells. On liner cementing jobs, the liner hanger packer provides a seal at the top of the liner, and the landing collar function is often integrated into the liner running tool assembly.

Fast Facts: Landing Collar

Primary function: receive and seat top cementing plug; provide bump pressure confirmation
Typical bump pressure increase: 200 to 500 psi above displacement pressure
Material: drillable cast iron, aluminum alloy, or composite for post-cementing drill-out
Two-plug system components: bottom wiper plug, top plug, float collar (with check valves), landing collar
Float collar position: 1 to 2 joints above the shoe, below the landing collar
Landing collar position: varies by design; typically 20 to 40 feet above the float collar
Pressure rating: up to 5,000 psi differential in standard designs; HPHT versions rated higher
Regulatory reference: API Specification 10D governs casing centralizer and cementing accessory requirements

Field Tip:

If bump pressure does not appear after pumping the calculated displacement volume, do not continue pumping blindly. Stop and evaluate: the plug may have failed (torn wiper blade allowing bypass), the displacement calculation may have been incorrect, or the float collar check valves may have held back the bottom plug and the cement column is shorter than planned. Check the tally sheet against pumped volumes, circulate to verify returns, and consult the cementing engineer before resuming. Overpumping past the anticipated bump with no pressure response can drive cement into productive zones or cause the shoe to blow out of position.

Plug-and-Dart Systems and Multi-Stage Cementing Collars

Modern cementing systems use plug-and-dart assemblies at the surface in the cementing head. Darts are smaller internal components released from the cementing head that travel inside the casing and engage with the wiper plugs, which in turn carry a wiping element that contacts the casing wall. This two-part design allows the dart to be pumped at high rate without damaging the wiper fins until it engages the plug body. The dart-and-plug assembly is confirmed at surface by a pressure increase before cement pumping begins, verifying that the system is properly engaged. After the job, the dart and plug assembly is drilled out along with the landing collar using a mill or tricone bit run on drill pipe.

Multi-stage cementing collars serve a fundamentally different function from landing collars. In wells with long casing strings or formations that cannot tolerate the hydrostatic pressure of a full column of cement, the cementing job is split into two or more stages. A stage collar, also called a differential fill collar or stage tool, is installed at an intermediate depth in the string. After the first-stage cement is placed below the stage collar, the tool is opened by mechanical action (dropping a dart or plug that shifts a sliding sleeve) to expose ports through the casing wall. Cement for the second stage is then pumped through these ports into the annulus above the first stage. A closing plug subsequently seals the stage tool closed. Stage cementing collars are engineered to withstand the pressure differentials of both stages and to close positively so the casing bore is fully open for subsequent drilling or production operations.

plug-landing collar: the full descriptive name emphasizing that the collar's function is to land and seat the cementing plug
cementing collar: a broader term sometimes used to describe any collar accessory used in cement job execution, including float collars and stage collars
baffle collar: a variant of the landing collar that uses an internal baffle with a restricted orifice rather than a full mechanical seat; used in some differential fill equipment designs
stage collar / stage tool: a multi-stage cementing device that opens to allow cement to be placed at an intermediate depth; functionally different from a landing collar but often discussed in the same context

Related terms: float collar, cementing, wiper plug, cement job, float shoe, casing, liner

Frequently Asked Questions About Landing Collar

What happens if the top plug fails to seat in the landing collar?

If the top plug fails to seat, bump pressure will not appear at the expected displacement volume. This is an abnormal situation requiring immediate investigation. Common causes include plug failure due to a torn or degraded wiper element that allows the plug to bypass the collar bore, incorrect displacement volume calculation leading the crew to stop pumping before the plug has arrived, or a plug that has been lost or separated from the dart that was supposed to drive it. The crew should first verify that the pumped volume matches the theoretical displacement volume within a 5 percent tolerance. If the volume is correct but no bump has appeared, pressure testing the casing from above can reveal whether cement has been displaced correctly or whether remedial cementing will be required.

How is landing collar position determined during casing design?

Landing collar position is specified by the cementing engineer based on the planned top of cement in the annulus and the volume of cement to be placed. The collar is positioned so that when the top plug seats in it, the volume of casing bore between the float collar and the landing collar equals the volume of cement calculated to fill the designed annular interval. This requires accurate knowledge of casing internal capacity, annular volume, and any losses to permeable zones. The float collar is placed one or two joints above the shoe to provide a small cement sump below it that cushions plug landing and protects the float valves from mechanical damage when the bottom plug ruptures.

What is differential fill equipment and how does it relate to the landing collar?

Differential fill equipment (DFE), also called auto-fill float equipment, incorporates a valve mechanism that allows drilling fluid to enter the casing from below while running in hole, equalizing pressure across the casing shoe and reducing the buckling risk on long strings in high-angle wells. A standard float collar with check valves prevents any fluid entry from below, which can create excessive buoyancy forces and require costly fill operations during running. DFE trips closed automatically when cement pumping begins, converting to a conventional float valve. The landing collar in a DFE string functions identically to a standard landing collar but must be designed to be compatible with the auto-fill valve below it. Most major cementing service companies offer integrated DFE packages that combine the float shoe, auto-fill float collar, and landing collar as a matched set.

Why Landing Collar Matters in Oil and Gas

The landing collar's bump pressure signal is one of the most reliable indicators available to a cementing crew that a primary cement job has been executed as designed. Without this confirmation, the crew has no direct evidence that the calculated cement volume has been placed in the intended annular interval rather than lost to a thief zone, pumped past the shoe into an open formation, or bypassed by a failed plug. Well integrity across the full life of the well, from drilling through production to eventual abandonment, depends on a competent primary cement job that isolates producing zones, protects freshwater aquifers, and supports casing against collapse. A failed or uncertain cement job requires costly remedial cementing, squeeze operations, or in severe cases, sidetracking the wellbore entirely. Understanding and correctly interpreting bump pressure is therefore a foundational competency for every cementing engineer and wellsite supervisor.