Pioneer Turbodrilling With 16 ½” Impregnated Bit in Deep Pre-Salt Well in Santos Basin

Abstract

Following the major pre-salt reservoirs discovery in Santos Basin by Petrobras in 2006, a large number of exploratory and development wells have been drilled in the area. More recently, some of those wells have been drilled in large wellbore configurations, mostly due to deeper pre-salt layers and geological uncertainties. This paper presents a case study on drilling a deep 16 ½″ vertical section at a deepwater location, where a turbine and an impregnated bit were used because of an extremely tough drilling scenario. This specific run achieved TD at more than 5000m, marking the first record ever of successfully running an impregnated bit of this size offshore. The basic well design data is shown, as well as the drilling program and offset well and other 16 ½″ bit records. The challenges that were found on drilling deep post-salt 16 ½″ sections in other locations and on the previous BHA runs with PDC bits on this section are highlighted and analyzed with drilling parameters. The impregnated bit specifications and the turbine characteristics are outlined taking operational recommendations into account. Available power at the bit was taken into consideration and the concern with its impact on drilling performance is explained through a comparison with other bit diameters which are widely used. The bit records, drilling parameters and UCS analysis of the section made clear that the turbine with impregnated bit was the most appropriate and effective drilling system for the scenario at the end of the section. A drilling time and cost comparison with other deep hard-formation-16 ½″ sections drilled in other locations shows that the use of this system may yield significant reduction in the total cost by shortening the overall rig time, making it the preferred option in some future challenging drilling projects. Lastly, further turbodrilling and impregnated bit improvements are suggested, theoretically analyzed and justified considering drilling performance maximization and drilling tools and rig equipment limitations.

Study of the Critical Speed of Ultra-High-Speed Diamond Drilling Technology in Marble

“…The impregnated diamond bit is the most commonly used drill bit type in deep hard rock geological drilling, meeting the drilling needs of highly abrasive formations with its unique self-sharpening process and rock-breaking method [7][8][9][10][11][12][13]. Its rock-breaking mechanism is similar to that of a grinding wheel working on a workpiece.…”

Design and Output Performance Model of Turbodrill Blade Used in a Slim Borehole

“…The common screw drill cannot be used under conditions of high temperature [5] with large rotational vibration. Practical work shows that an all-metal turbine drill with impregnated diamond bits [6] has good temperature adaptability and high efficiency in terms of the hard rock formations [7]. The first application of turbodrills and hybrid bits for drilling cretaceous formations with high chert content was reported in the south Mexico region [8].…”