In April 2012, the world's first 16-in. solid expandable tubular (SET) liner was run to depth and successfully cemented and expanded. The installation of the large diameter liner marks a significant shift in the application of expandables from deeper contingency applications to planned hole-conservation designs in the upper wellbore.

The purpose of the installation was zonal isolation. In Saudi Arabia, the Uthmaniyah field, the prolific Arab D reservoir has been produced for many years, resulting in lower pore pressures than the shallower Arab A, B, and C reservoirs. Due to the differences in pore pressure, isolation between the Arab D and Arab A, B, C reservoirs is required to efficiently drill some of these wells.

The 16 × 18-5/8-in., 115 lb/ft open hole liner (OHL) system isolated the Arab D reservoir by covering the Arab A, B, and C reservoirs while minimizing the loss of hole diameter to maintain the original wellbore design and drilling tools. Both objectives were safely and successfully achieved with the running and expansion of 1,708 ft (pre-expanded length) of 16-in. solid expandable pipe, hung as a liner and anchored into the 18-5/8-in. casing.

To isolate the pressure differential, the 16-in. SET liner was installed in a negative pressure environment. Once the liner was installed, the mud weight was reduced to drill the lower pressure Arab D reservoir and the remainder of the hole section. From a reservoir management viewpoint, this installation eliminated cross flow from the higher pressure Arab A, B, and C into the Arab D reservoir, thus preserving the pressure regime of the oil producing Arab D.

Additional benefits of the 16-in. expandable liner included an increase in ROP in the hard rock environment, the elimination of two-stage cementing requirements and the associated risk of stage tool failure, and reduction of hook load requirements associated with large, long casing strings.

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