Operators for deepwater and extended-reach wells, where daily rig costs can exceed $500k per day, are continuously exploring methods to reduce nonproductive time (NPT) and increase operational efficiency. One particular area of interest is the deployment of liner strings, which are commonly used as an alternative to long casing strings to minimize well construction costs and increase drilling efficiency. For deepwater and highly deviated applications, hydraulic liner hangers are predominantly used over mechanical tools due to the limitations of pipe manipulation needed to set the hanger. The traditional method for setting a hydraulic liner hanger includes the use of one or more activation balls dropped from surface so that pressure can be applied to the workstring to function the hydraulic liner hanger and running tool. However, in deepwater and extended-reach applications, the time to pump or gravitate the ball on seat can take up to 3 hours. In addition, there are many cases where the ball never properly lands on seat, which can lead to days of more NPT. Developing a liner hanger system that does not rely on dropping activation balls from surface, nor rely on pipe manipulation can reduce the time required to run the liner hanger and minimize issues that lead to increased NPT.
This paper presents how a new liner hanger system was developed to use simple mud flow signals to remotely communicate with a downhole controller located on the workstring. The downhole controller receives the specific activation signal from surface and then relays that signal to the liner hanger or running tool via an acoustic signal. The liner hanger and running tool are then actuated with an electronically triggered hydrostatic actuator.
This new system does not require dropping activation balls from surface, simplifying system hook-up and reducing the amount of time required to set the liner hanger. The system also allows a solid liner hanger body with no pressure ports, eliminating the potential leak paths inherent to hydraulic liner hangers.
The novel approach to design and develop the remote liner hanger system to minimize operational risks and reduce development time will be discussed in detail. This includes the evolution of the remote system from field-proven hydraulic liner hanger technology and the results from testing performed to qualify the remote communication methodology. This liner hanger system improves well construction efficiencies and is a step in the direction of a smarter and safer oilfield through more automated operations.