HPHT Expandable Liner Hanger Technology with Superior Pressure Integrity
Authors: Royer Edward Shannon , Turney Robert Albert 
Published: April 2019

As operators in the oil and gas industry continue to search for larger oil deposits in areas that are considered High Pressure and High Temperature (HPHT) environments, manufacturers of liner hanger/packer systems must conceive and validate designs that can support these projects. The XPak™ liner hanger/packer system is an expandable product that offers metal-to-metal and elastomer sealing capabilities at the liner top in host casing, capable of superior hanging capacity and seal integrity for installing casing strings of various lengths. The expansion process is achieved using a multi-piston hydraulic running tool with pressure application to displace an Expander inside the XPak hanger body. The displacement of the Expander inside the XPak hanger body relies on interference between the components to radially grow the hanger body to contact and interfere with the host casing. This interaction provides the sealing and anchoring capability of the XPak system. The Expander provides tieback capability via a polished bore receptacle and remains installed inside the hanger body for the lifetime of the installation.
Operators are implementing robust host casing designs with less variance in wall thickness to utilize tubulars with higher burst and collapse ratings than those manufactured to API standard variances. The combination of higher burst pressure ratings for the host casing and limited variance on the inner diameters provides an ideal partner for the XPak system. Expandable products rely on a narrower host casing inner diameter range to create the interference needed for optimum performance, as opposed to conventional liner hanger systems which work over a broader diameter range.
An ISO 14310 V0 qualification of a 7-5/8 × 12-1/4 HPHT XPak liner hanger/packer system for a major operator in the Gulf of Mexico successfully achieved testing milestones of 15 ksi internal pressure with a combined loading of 1,000 kips in tension at 375°F. The system was also qualified at a low temperature of 60°F reaching a successful test pressure of 21.75 ksi internally with a combined tension load of 1,000 kips. These testing requirements were provided in the customer's statement of requirements to handle extreme well loading conditions. FEA modeling is the primary tool for XPak design and focuses primarily on identifying and predicting material strain to help determine the system capabilities under simulated pressure and loading conditions. The distinct geometry and controlled deformation of the hanger body during expansion are simulated using FEA software to provide guidance to meet design parameters to reach high levels of performance. The initial conceptual design is taken through a complete range of potential well scenarios including: casing inner diameter ranges, maximum and minimum setting forces, geometric tolerancing, friction factors, and transient thermal loading. The results are compiled and reviewed to determine the optimal design model to satisfy the customer's requirements.
Validation testing and field installation performance for this product line has been successful. The use of analytical tools for design along with improvements in material options and manufacturing processes has been instrumental in the continued growth of the XPak liner hanger/packer system.