VersaFlex® and XtremeGrip® ELH systems combined in sour environment

Overview

An offshore well was drilled to a depth of more than 20,000 ft to allow the operator to explore several zones of interest from a single wellbore. During the design and execution phases, multiple liner hanger systems were deployed to reach the required depth without jeopardizing the overarching design. Due to the challenging sour environment and complex design, the VersaFlex® expandable liner hanger (ELH) and XtremeGrip® ELH systems were selected for the job.

Challenge

The final design required four sections to be isolated with cemented liners. Each section presented potential operational issues that required ELHs with unique capabilities.

Section 1: 16-in. liner × 20-in. parent casing

A salt formation with movable sands was encountered during the drilling phase. Movable sands are known to pose operational issues related to well control, kicks, and tight spots.

Section 2: 13 5/8-in. liner × 16-in. parent casing

After the 16-in. shoe was drilled, the hole section exhibited balloon effects, which were quickly controlled. The remaining part of the hole section was drilled without any issues. Although no significant liner-deployment challenges were expected, standard expandable liner hanger (ELH) protocol necessitated pre-job planning and risk mitigation.

Section 3: 11 3/4-in. liner × 13 5/8-in. parent casing

This section was considered the most challenging due to the depleted Wasia formation. It required drilling through the formation and installing an intermediate liner to isolate the wellbore and prevent compromise of subsequent sections. Depleted zones often present operational challenges related to differential sticking, excessive fluid loss, and potential well control.

Section 4: 9 5/8-in. liner × 13 5/8-in. parent casing

This hole section involved drilling through the Nahr Umr, Thamama, and Salld/Rayda formations. At 16,939 feet, hard rock was encountered, prompting a reduction in hole size from a 12 1/4-inch reamer to a 10 5/8-inch bit. Similar to Section 2, no significant liner deployment challenges were observed; however, standard expandable liner hanger (ELH) protocol required pre-job planning and risk mitigation.

Results

Both the VersaFlex and XtremeGrip ELH systems enabled the operator to reach the required depth, successfully set the liner hangers, and execute cementing, even in the presence of a complex well profile. Design characteristics of both ELH systems confirmed the following advantages:

• Capability of high reaming, flow, and torque rates with no risk of premature release or set. Multiple challenges were overcome in several hole sections.
• Reaming confirmed the potential of the VersaFlex and XtremeGrip ELH systems (max. torque = 24K ft-lb, RPM = 20, max. SOW = full liner weight).
• Providing a smooth radial flow path for an improved ECD profile during cement operations, outperforming a conventional liner hanger system, and aiding cement above the TOL.
• Incorporating lessons learned from multiple service functions into the job design helped achieve the desired results and ensure risk mitigation.

The VersaFlex and XtremeGrip ELH systems helped overcome a variety of issues (over multiple hole sections with significantly distinctive characteristics) without the risk of presetting or pre-releasing. The technology and services provided a sealed liner top that followed a preplanned design, which was adjusted as lessons were learned to help mitigate potential risks. No HSE or service quality incidents were encountered, and each hole section was completed efficiently and on time.