Low-pressure reservoir characteristics are not often considered as a contributor to installation failure during deployment of conventional hydraulic-set liner hanger systems. Often, this situation occurs in cases where there is a sudden change in the well properties. If this phenomenon occurs, the outcome of a job can be changed from success to a failure. These low-pressurized reservoirs are considered as being capable of being maintained with fluid weight (balanced) rather than as candidate for one that is controllable by lighter-weight fluids (less than 8.3ppg) (underbalance). In the balanced wells, liner installation issues can range from sudden high-rate fluid loss causing differential pressure sticking of the liner, inability to get to depth, or inability to place cement around the liner forming the primary liner top seal.

In the underbalanced wells, issues such as difficulty in running the liner to bottom, and premature setting of the liner hanger during deployment of the liner can be seen, and during the critical stage of cementing the liner, problems such as inability to circulate at rates and pressures, inability to move the liner during the cement job, and inability to provide a liner-top seal prior to releasing the running tool can result. Such are the issues faced by operators in different areas of the globe.

A solution to these issues has been identified. An expandable liner hanger (ELH) system, which allows the annulus fluid to be isolated from the work string fluid during deployment and throughout the cement job because of its pressure-balanced configuration can resolve these problems. In addition, the ELH system can be set up for liner drilling, enabling the liner to be drilled through the low pressure reservoir, the shoe to be cemented, and the liner top to be isolated upon setting. Multiple jobs have been performed successfully in this manner, saving the operator several days of rig time through one or more benefits provided by the system; i.e., getting the liner to bottom, providing a premium cement bond, and eliminating remedial cementing jobs. Selected cases concerning low-pressured well types will be the focus of this paper.

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