By Scott Benzie and Arthur Stautzenberger, Coretrax

As the call for sustainability grows louder, the oil and gas industry finds itself between a rock and a hard place. Global energy demand remains stable and traditional hydrocarbons show no signs of disappearing from the energy mix. New reports suggest that up to 35% of UK energy consumption will still be met by fossil fuels in 2050. As a result, increasing pressure to run operations as efficiently as possible, with minimal impact on the environment, is at the top of operators’ agendas.

The industry’s increased focus on maximizing production while reducing the associated carbon footprint has paved the way for real technological advancements, and expandable liners have emerged as a key enabler to enable operators to extend the life of existing, and often mature, fields without limiting drilling capacity. By leveraging already existing infrastructure, significant sustainability reductions can also be achieved.

Furthermore, unlike conventional liners or casing strings, expandable liners minimize the loss of internal diameter of the well casing, meaning that problematic zones can be remediated without negatively impacting production rates. This is particularly important in the case of mature wells that face unique challenges such as sand infiltration and formation damage. Ultimately, the application of the technology means that operators can continue to produce from a reserve that may have been considered unviable.

Case study

This was demonstrated by Coretrax, an Expro company, during a recent project for a major Norwegian operator. Proprietary scale-out technologies were deployed to enable an underproducing well to be converted into a multilateral well to increase recovery using existing infrastructure.

The original well design called for a sidetrack of the 13-5/8” casing at a shallow depth and the installation of a new 10-3/4” liner. This approach was successful in isolating formation issues, but it was becoming increasingly difficult to reach reservoir targets with a shallow sidetrack. After extensive consultation with the client, Coretrax’s ReLineDL was selected to assist with this challenge. The tool itself is designed for open and cased hole environments and the bottom-up expansion system uses hydraulic pressure to pump an expansion cone from the bottom of the liner to the top. The system provides the ability to add a casing string in planned or unplanned scenarios with minimal loss of borehole diameter.

This project presented unique challenges, most notably the presence of depleted zones and shallow gas, which posed an increased risk of losses or gas inflows during drilling. To mitigate this, the operator elected to drill a small section of the 10-3/4” casing prior to installing an expandable liner. This allowed the gas cap to be isolated without reducing the ID, meaning both the reservoir and multilaterals could be drilled with an 8-1/2” bit.

Over 502 m of liner was laid at one time, with the inner string subsequently inserted; the system itself was operated until it reached the target depth of 2,144 m, where cement was pumped and moved to provide isolation. After the cement arrow landed, hydraulic pressure was built up to begin the expansion process, and after removal of the inner string, the liner was successfully pressure tested to 2,650 psi before the shoe was drilled out.

The expandable liner allowed for an 8-1/2” post-expansion drift ID, meaning a traditional 8-1/2” main wellbore section could be drilled to the desired depth and a main well screen section installed. A guide rod was oriented and installed in the expanded casing above the main well completion so that it could be milled and a traditional 8-1/2” lateral section drilled to increase reservoir exposure. A second 8-1/2” lateral section was drilled and installed, ultimately converting an underproductive single well into a tri-lateral well with improved
production speeds.

The successful completion of the project demonstrates advances in scale-out technologies that enable improved performance of traditional oil and gas wells while achieving sustainability goals. By ensuring operations could continue as intended, Coretrax helped maintain the economic viability of a depleted field, reducing the need for additional wells to be drilled.