Use of Ducorit® S1 for Skirt Pile Grouting at CPDR-A for Sarawak Shell

CASE HISTORY Structural Services

Prior to offshore mobilisation, the jacket structure was in-spected in the fabrication yard by Densit Engineers at the re-quest of TLO and Shell to ensure that the grout lines and swept bends were correctly fitted and positioned to optimise offshore grouting works and reduce in-stallation time.

Densit were requested to mobi-lise 129 tons of its UHPC Du-corit® S1 material, five experi-enced grouting engineers, la supervisors, and support team for 24 hours operation and a full grouting spread including mo-bile testing laboratory ready for work onboard Material Barge Eastern Rose, soft moored to Derrick Lay Barge Quippo Prakash 2000 (DLB QP 2000), located approximately 20m from the CPDR-A jacket.

The jacket and grout lines on jacket legs were pre-installed by TLO and made ready for grout-ing. The work must be com-pleted within a short time frame allocated to Densit and

the UHPC must develop strength extremely quickly after grouting, in order for TLO to install the topside. Inflatable grout packers, preinstalled at the base of the skirt pile were filled with nitrogen to contain the grout within the annulus.

Prior to grouting works all pri-mary and secondary grout lines were flushed with tracer dye dissolved in sea water to estab-lished flow and check for block-ages. During the tracer dye flushing it was found that one of the flooding valves on one pile sleeve section used for jacket

installation was leaking. Du-corit® S1 was then pumped through a series of flexible 3” and 2” hoses up to the 2” grout lines on CPDR-A deck and then

92 m down to the skirt pile inlet of all seven piles in succession. A Ducorit® S1 plug was set for the leaking skirt pile annulus and allowed to harden for 24 hours whilst the grouting for remaining skirt piles were com-pleted. After completion of grouting for all seven skirt piles, the first skirt pile was grouted on top of the plug to complete all operations.

The ultra fast strength develop-ment and high final compres-sive strength (average of 110 MPa) offered by Densit’s Du-corit® S1 made it the perfect solution for creating grout plug having fast strength develop-ment . Ducorit® S1 is a pre-mixed product that only re-quires a small prescribed amount of water to be added. This simplifies the execution on-site and ensures the standards demanded of a high perform-ance material such as Ducorit® S1 are met every time

QUICK FACTS Location: Offshore Sarawak, Malaysia Type of work: 8 x Skirt pile annulus grouting Material Used: Ducorit S1 Grouting Days: 3 including pre-grouting flush testing Total Amount of Mate-rial: 129 tons (55 m3)

In October 2010, TL Offshore Sdn Bhd had a require-ment for the grouting of eight (8) skirt pile annuli for the CPDR-A jacket installation offshore Sarawak, for Sarawak Shell Berhad. The platform is to be located in the South China Sea at water depths of approximately 92 m at 155 km offshore of Bintulu, Sarawak Malaysia. Ducorit® S1 was used for the grouting for its fast strength development, high compressive strength, workability and self-sealing properties.

ITW Densit ApS 46, Gasvaerksvej DK-9000 Aalborg Tel.: +45 9816 7011 mail@densit.com www.densit.com