Planning Advanced Liner Systems in Complex Wells to Mitigate Well Integrity Issues
Authors: Hawthorn A. , Osunjaye G. , Nordenstam L. , O'Keefe K. 
Published: November 2024

Thousands of liner hangers are run on wells around the world on an annual basis. These are to reduce the time and risk, with associated cost of running long casing strings. In fact, it may on some wells be impractical for a rig to run a long casing string. Obviously correctly positioning and landing a casing or liner correctly and then adequately cementing the same are absolutely critical with regard to well integrity and is the principal form of barrier control on most wells. Additionally, there are often both state and individual companies’ regulatory requirements to be satisfied during their application. The first iteration of these liner hanger systems would require a mechanical actuation, this could be rotating and or reciprocating the drill pipe in order to deploy the liner system. In the last several decades there has been an increasing complexity of wells, particularly in relation to the complexity of the well profile with thousands of highly deviated or horizontal wells. With increasing deviation and complex trajectories comes a subsequent difficulty in the ability to activate the liner system through rotation and reciprocation. To overcome these challenges the industry then developed hydraulically actuated systems, and these are found in both conventional and expandable liner hanger systems. The traditional method for setting a hydraulic liner hanger is through dropping an activation ball. This can be either a single activation or a multiple activation device. The hydraulic activation allows for reciprocation and rotation, within the limits of the well deviation. Dropping a ball and landing it on a ball seat creates a pressure increase to the work string which would then activate the liner hanger and running tool.

However, it is still the case that there are multiple failures of liner hanger setting, and indeed of getting liners to bottom safely. In complex well trajectories, in high pressure high temperature wells and in wells with very narrow mud weight windows, or under managed pressure or in heavy or total loss situations, the inability to set the liner hanger systems correctly or in the correct place can lead to significant Non-Productive Time (NPT). It may also compromise the well integrity. This, amongst other factors, is generally associated with not having access to what is happening downhole, relying only on surface indicators and not landing the ball on the seat correctly.

We will demonstrate in this paper a system that allows both real-time data to be sent both from just above the liner hanger, but also along the string whilst running the system. This acoustic telemetry system, which transmits data through the wall of steel drill pipe without the need for surface or downhole modification of existing systems includes measurements of downhole weights, downhole torques and internal and external pressures and temperatures. Additionally, the system transmits all the time and can be run independent of flow or fluid and also operates whilst tripping. The system is also fully through bore allowing the passage of balls, bars or even wireline tools through the bore. This system has been operating for several years now sending data back up the string through an imaginative number of different well operations. However, combining the measurements of this acoustic telemetry system with its inherent capability to also be bi-directional means that not only can data be sent up from downhole and along the string, but also acoustic commands can be sent down to activate downhole devices, in this case the liner hanger and running tool. The whole enabling a system approach to overcome some of the challenges outlined above.

The development of such a system providing both real-time downhole measurements and does not rely on mechanical manipulation or dropping an activation ball from surface has the potential to dramatically decrease the number of high impact NPT events and increase the overall operational capabilities of liner hanger systems. It also allows us to see through to the possibility of running and activating liner hangers in well trajectories and designs that had previously not been considered due to the limitations of existing systems.