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# Downhole rotary steering tool

IP.com Disclosure Number: IPCOM000199506D
Publication Date: 2010-Sep-07
Document File: 1 page(s) / 11K

## Publishing Venue

The IP.com Prior Art Database

## Abstract

This steering tool incorporates two steering principles: Push and Point the Bit. The huge advantage of this combination is the ability to achieve high BUR (~15°/100ft) with smooth borehole walls during inclination hold section. The idea of this invention results from the drilling direction equation: Drilling direction = IBresulting force direction + (1-IB)bit face direction IB is the bit anisotropy factor with a value between 0.15 and 0.2. This factor is a measurement for the side cutting ability of the bit. The main conclusion of this equation is that ~80 of the drilling direction results from the bit face direction and only ~20 are resulting from the force direction. For achieving high BUR it is optimal to tilt the bit. With this steering principle it is difficult to drill a smooth bore hole due to the high influence of the tilt angle. For high BUR (15°/100ft) the angle has to be relatively small (1-1.5°). For small trajectory corrections the angle control has to be very accurate. For small trajectory corrections the bit should be centralized in the bore hole by side forces. This steering principle is very useful for small trajectory changes but has problems to achieve high BUR. This new drilling tool incorporates both steering principles: the drive shaft can be tilted for drilling the build section with high BUR. In tangent sections (inclination hold sections) the drive shaft is set straight (fixed without tilt) and the drilling influences are corrected by side forces. The tool design has a mechanism for tilting the drive shaft. Behind the tilt mechanism a non-rotating sleeve with ribs or rotating ribs can be located. The distance between the bit and the ribs is relatively large in comparison to current tool designs, but the correction force should be large enough to navigate the tool in inclination hold sections. So the advantages of both steering principles can be combined in one tool.

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Title of Invention:

Downhole rotary steering tool

Abstract of the Invention:

This steering tool incorporates two steering principles: Push and Point the Bit. The huge advantage of this combination is the ability to achieve high BUR (~15°/100ft) with smooth borehole walls during inclination hold section.

The idea of this invention results from the drilling direction equation: Drilling direction = IBresulting force direction + (1-IB)bit face direction IB is the bit anisotropy factor with a value between 0.15 and 0.2. This factor is a measurement for the side cutting ability of the bit. The main conclusion of this equation is that ~80 of the drilling direction results from the bit face direction and only ~20 are resulting from the force direction. For achieving high BUR it is optimal to tilt the bit. With this steering principle it is difficult to drill a smooth bore hole due to the high influence of the tilt angle. For high BUR (15°/100ft) the angle has to be relatively small (1-1.5°). For small trajectory corrections the angle control has to be very accurate. For small trajectory corrections the bit should be centralized in the bore hole by side forces. This steering principle is very useful for small trajectory changes but has problems to achieve high BUR. This new drilling tool incorporates both steering principles: the drive shaft can be tilted for drilling the build section with high BUR. In tangent sections (inclination hold sections) the drive shaft is se...