Technology from Europe: United Kingdom

Expandable liner hanger deployed

 The hydraulically expanded design was successfully set in a challenging directional CWD well in the North Sea. 

Chris Nussbaum, READ Well Services, Aberdeen

Downhole expandable technology took a big step forward in January 2007 with the first-ever expansion and setting of an expandable liner hanger in a casing-directional-drilling (CDD) well in the Norwegian sector of the North Sea. The operation used READ Well Services’ Hydraulic Expandable Tubular System (HETS), the only system for expanding concentric downhole tubulars using direct hydraulic pressure, Fig. 1.

Developing a completely new liner-hanger design in just 14 months was a challenge in its own right, but this project also delivered a hanger-packer assembly that would withstand the rigors of 20 days in a casing-while-drilling (CWD) environment before being expanded and set with a load capability of over 200 t and a 5,000-psi, gas-tight seal tested to ISO 14310:V0.

The well itself presented the operator with extreme challenges, even by the high standards of the North Sea. The twin-wellhead design required CDD to an MD of over 12,000 ft with up to 70° deviation, and conversion of the 73⁄4-in. casing-drillstring to a liner, with an integral, completely gas-tight, 200-t-capacity hanger-packer assembly set at 5,000 ft in the 103⁄4-in. parent casing.

DEVELOPMENT

The fast-track project required the design, construction and testing of a series of six liner hangers from prototype to final design. The extensive hanger test program set out to establish the load and sealing capability of the liner hanger as well as its ability to withstand a CWD environment. The gas-sealing capability provided an essential barrier against gas migration potential in the well.

The tension/compression test-bed facility at READ was used to subject the test pieces to loads up to 360 t. Each test piece was a full-sized hanger expanded and set in a 103⁄4-in. casing section. The liner hanger was tested in accordance with the ISO 14310 packer standard, which required the liner hanger to be cycled through both internal and external gas and hydraulic pressures of 5,500 psi across a range of temperatures from 15°C to 115°C. A leak-rate of zero (V0) was successfully established in the tests.

Fig. 1. HETS liner hanger.

Subjecting a complete liner hanger and casing assembly to nearly 1 million bend cycles under pressure evaluated the mechanical durability of the hanger. The 5,500-psi-rated hanger seal remained intact throughout.

FIELD APPLICATION

With the drillbit at a depth of about 7,000 ft, the HETS liner hanger was installed as part of the CDD string. The string then drilled ahead to the 73⁄4-in. shoe depth at 12,000 ft. The casing shoe was cemented, and the HETS expansion tool was then run into the well on drill pipe and engaged in the liner hanger using an integral latch device. The HETS system was activated, and it generated 21,500 psi hydraulic pressure (above hydrostatic), expanding the 11-ft-long hanger by 15% in diameter, thus successfully ”setting” it in the 103⁄4-in. parent casing. The water-based hydraulic fluid for the expansion was carried in a reservoir compartment in the drill pipe immediately above the expansion tool.

Successful installation was confirmed by a 5,000-psi pressure test, after which the entire 5,000-ft casing string above the HETS liner hanger was retrieved from the well by activating a specially designed release mechanism.

EXPANDABLES ON WIRELINE

Beyond the expandable liner hanger, the project team set about to upgrade the design of the downhole expansion tool, which had already been developed for use with internal and external casing patches.

Most significant was the design and construction of a wireline-deployed hydraulics module. The electrically powered unit delivers the fluid power required to drive the downhole intensifier. The combination of the hydraulics module and the intensifier delivers up to 29,000 psi of controlled hydraulic pressure to the expansion seal unit, as well as real-time monitoring of the expansion process. Unfortunately, the tool test program was not completed in time for the first operation, which was carried out on drillpipe, but this deployment method is expected to provide considerable operational time savings on the next well.

The wireline development also opens up an intriguing new set of options for solid expandable devices, which are of particular significance in the subsea well intervention environment. 

THE AUTHOR
	Chris Nussbaum is the marketing manager of READ Well Services. He has more than 20 years’ experience in the well intervention and well management sector. He holds a BS degree with honors in physics from York University.