New Concentric Dual Diameter Fixed Cutter Technology Bit Drills 56 Faster and Saves Operator Drilling Time in Directional Application Through Challenging Abrasive Sandstone in One of the Largest Reservoirs in the Middle East

Abstract

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 several times in a tangent, directional application and J-shap 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 directional 8¼ in. PDM (0.16 R/G, 7/8 lobes, 4 stages, 1.5 BH) BHA was tested in a directional application J-Shape well in Burgan Field, South of Kuwait. The bit was able to deliver improved performance by drilling the tangent section from 4345 ft to 6019 ft from Ahmadi to Burgan formation, total 1674 ft in 17 hrs with 98.4 ft/hr. The bit showed excellent steerability, building from 39 deg to 43 deg with 3 deg/100 ft max DLG severity. The section lithology consists mainly of Shale, Limestone & Sandstone. The performance capability was confirmed when the second bit run in conjunction with directional 8¼ in. PDM (0.16 R/G, 7/8 lobes, 4 stages, 1.5 BH) BHA was tested in a directional application S-Shape well in Burgan Field, South of Kuwait. The bit was able to deliver improved performance by drilling the dropping section total 940 ft from Ahmadi to Burgan formation. The bit showed excellent steerability, dropping from 15 deg to 0 deg with 3 deg/100 ft max DLG severity. The section lithology consists mainly of Shale, Limestone & 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 56% saving the operator drilling time and making the concentric dual diameter bit design the top performing drill bit in the field.

Design of bottom hole assemblies with two rock cutting tools for drilling wells of large diameter

“…For drilling large-diameter wellbores in foreign practice, step-shaped bits are widely used [1], as well as drilling with the use of eccentric reamers set in the BHA, which allow to make an underreaming in certain areas, since their functional diameter can be changed [2]. It is expedient to use this me-thod when drilling in salt deposits or intervals where the wellbore can be narrowed for other reasons.…”

“…Using the experience of drilling with eccentric bits, concentric hard-alloy bits have been developed, which, due to the setting of teeth on the entire annular surface, provide a higher drilling velocity, allow for increased advance per bit and drill the wellbore with greater accuracy. The pilot part of the bit is 75-80% of its entire surface area [1].…”