First-of-A-Kind Batch Installation of High-Torque Threaded Drilling Riser Saves the Operator $500,000.00
Authors: Chang B. T. , Reed Kit , Yeap Fabian 
Published: March 2018

Because of the inherent risks, costs, and technical complexities, Deepwater development often requires customized solutions that employ life-of-well systems to enhance safety and boost field economics. All aspects of Deepwater well construction, including rig design, riser installation, pipe handling, and connection makeup and integrity must be implemented with a level of precision and service quality that enables the wells to produce safely for 30 or more years.

For a multi-well Deepwater project in Southeast Asia, a major Operator engineered a tension-leg platform (TLP) with 24 slots for prospective development wells. The vertically moored floating platform moved laterally with changing weather and ocean conditions, and it was especially suited for the 1,640-ft (500-m) water depth in the project. TLPs typically use a top-tension riser (TTR) run between the platform and seabed. The riser was securely connected to the wellhead with an external tieback connector, and it remains in place for the life of the well.

For this project, the Operator deployed a specially designed TTR that could be used for both drilling and production for the first time in the Eastern Hemisphere. Unlike conventional systems that use separate risers for drilling and production, the single-casing combination (SCC) TTR used the same outer riser for drilling, completion, production, and workover operations. This approach enabled the Operator to eliminate the time and cost of installing multiple sets of risers, and it streamlined the process of drilling the wells. The Operator's unique SCC-TTR design also enabled batch installation of TTR strings, resulting in improved operational efficiency & significant time savings.

For a first-of-its-kind installation in Asia, the vendor engineered a fit-for-purpose tubular handling and makeup package for the SCC-TTR. The integrated, customized solution which was designed for use on the TLP combined several tubular running technologies and tools specially designed to handle non-API pipe sizes. As a whole, the package was able to handle the TTR joints, monitor and evaluate torque data for well integrity, and efficiently makeup the high-delta torque connections required for each well— all with the least possible disruption to the existing rig equipment.

The customized, purpose-built tubular running equipment enabled completing the initial riser installation on the TLP in 98.5 hours. The second riser installation was completed in 81.5 hours. The remaining nine installations were batch installed in two phases with an initial target of 43 hours per installation. By implementing lessons learned and optimization of equipment, the remaining installations were completed nearly thirty-seven hours ahead of scheduled time, which resulted in a savings of US$500,000 for the Operator.

This paper discusses (1) engaging with the Operator and rig contractor on requirements and limitations as well as collaboration between the global and regional teams to meet the customer's timeline and requirements while overcoming limitations of the rig, (2) meeting the challenges with customized, engineered solutions that satisfy industrial standards, (3) pre-qualifying the systems for penetration and torque, (4) providing a complete commissioning solution to prepare against uncertainties, and (5) focusing on cost and time savings to increase efficiency in a challenging market.