This paper will discuss the deployment of the concentric dual diameter fixed cutter bit technology which was introduced in January 2015. The bit was deployed and tested four times in a vertical application and S-shape wells in Burgan Field, South of Kuwait and achieved the fastest penetration rate in the application.

The concentric dual diameter bit is composed of a smaller pilot and a larger reamer section, where the reamer section dictates the final drill size. Conventional fixed cutter bits take very little advantage of stress relieving the rock, as it only affects the borehole wall. Concentric dual diameter technology bits are able to initially drill with a leading smaller pilot section efficiently to relieve the stress of the rocks. Subsequently, the reamer section removes the stress relieved rock with lower mechanical specific energy compared to regular fixed cutter bits, giving it the advantage to generate higher penetration rates. Another advantage of the concentric dual diameter technology bits is the stability of the bit, since two gauge sections are available to be in constant contact with the borehole while drilling.

The first 12 ¼ in. concentric dual diameter technology bit in conjunction with a packed rotary BHA was tested in a vertical application in the Burgan Field, South of Kuwait. The bit was able to deliver improved performance by drilling two wells from shoe-to-shoe to section TD of 1372 ft with an ROP of 152.4 ft/hr where the lithology consisted of shale and sandstone.

The performance capability was confirmed when the second bit drilled two wells shoe-to-shoe to sections to a TD of 2263 ft with ROP of 161.6 ft/hr. and achieved top record runs in south Kuwait for vertical applications and S-shape wells and consisted of similar lithology of shale and sandstone.

The 12 ¼ in. concentric dual diameter was able to surpass the average rate of penetration for the same application in the Burgan Field by 100% saving the operator drilling time and making the concentric dual diameter bit design the top performing drill bit in the field.

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