Weatherford’s industry-standard Sub-Surface Release Mid-Bore Top Plug is a premium cementing plug that incorporates a ball seat for mid-diameter liners. The plug is designed for use with 9 5/8-in. and larger hydraulic liner systems, where the minimum drift of the drillstring is 2.54 in. (64.5 mm). This plug performs multiple functions during liner-setting and cementing operations. When the setting ball lands in the seat, applied surface pressure facilitates setting the hydraulic hanger and releasing the hydraulically released running tool. During the cementing job, the plug separates the top of the cement column from the displacement fluid, preventing cement contamination and confirming cement displacement when the plug lands on the float or landing collar at the liner bottom.
The Sub-Surface Release Mid-Bore Top Plug features a patented integral-pressure equalizer to prevent premature release. It also has a more reliable shear-ring ball seat and plug-launch design, resulting in more accurate shear-pressure activation.
When run on the outer joints connected to the retrievable seal mandrel (RSM) packoff, the plug does not move when picking up the setting tool, thus confirming release from the hanger system. This feature prevents damage to, or accidental release of, the plug and is a proprietary design advantage of the Weatherford liner-hanger system.