Metal Expandable Packer Secures the Integrity of a Cemented Casing Shoe and Protects the Caprock from Potential High Injection Pressures
Authors: Hazel Paul , Jacobsen Brian , Huse Arve , Rygh Synnøve Lind , Jørgensen Paal Ludvik , Lønning Petter , Strømsvik Frode 
Published: October 2023

The Edvard Grieg platform and Solveig subsea field developments have four horizontal wells with a novel cap rock protection technology in place for water injection service. The 9 5/8" casing shoe is positioned within the cap rock providing the primary well barrier. However, the cap rock requires protection from potential out-of-zone fracturing during high pressure water injection. Options to protect and seal across the cap rock were cemented 7" liner, expandable cemented liner, or Metal Expandable Packers (MEP). With the MEP having the benefit of qualification to ISO 14310 and API 11D1.

The 9 5/8" shoe was landed and cemented at the bottom of the cap rock, the mud weight lightened and the 8 ½" hole was drilled to Total Depth (TD). A single trip liner was deployed consisting of a liner hanger, a 7" casing with MEP and with contingency swell packers, positioned at the top of the injection reservoir, and 6 5/8" and/or 5 ½" sand screens with annulus flow prevention. The MEPs were expanded with 345 bar pressure after setting the liner hanger. On the Solveig wells, filter cake breaker fluid was reverse circulated across the reservoir and up the screen and landing string through an electric toe valve, before a ball valve was closed mechanically with an Radio Frequency Identification (RFID) tag operation as back-up.

The MEP created a fracture propagation safety barrier between the top injection point and the casing shoe (bottom of the cap rock). This subsequently lowered the risk of out-of-zone cold water injection in a weaker zone between the cap rock and the injection reservoir. The solution also protected the formations behind the 9 5/8" casing up to the production packer location. Substituting the alternative cemented liner options with the MEP annulus barrier and anchoring system saved considerable rig time and cost with reduced operational risk. Maintaining the 8 ½" hole to TD avoided slim-hole related risk and maintained a standard casing program, while enabling 6 5/8" × 5 ½" screens for a considerably longer reach with respect to torque and drag. The overall injection capacity was increased due to the larger bore and lower pressure losses. The MEP can facilitate short "bursts" of water injection at pressures above the minimum horizontal stress of the reservoir rock, which can create new flow paths. This provides a contingency in the event of the Solveig "no flow back" filter cake breaker solution was not successful, or the Edvard Grieg production clean-up was not successful, or injection was not sustainable over time due to formation plugging.

Many wells are challenged with depleted zones above, across or below the cap rock which often challenges the positioning of the production or injection casing shoe. The ability to achieve a competent well barrier and protect against out-of-zone injection and undesired fracture propagation is a valuable solution addition. This solution addressed the challenge, securing a more robust and long term well integrity situation at substantially reduced cost and risk. The operator is considering wireless pressure gauges above the MEP in future applications to consistently confirm the MEPs as working barriers against high injection pressures.