Self-rotating Side Cutters for Borehole Enlargement

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Solution Overview

Problem

Existing borehole enlargement tools face challenges with increased drillstring torque and vibration when using passive cutters, limiting the achievable borehole diameter.

Innovation Solution

The integration of self-rotating, actively driven side cutters with non-circular cross sections in a drillstring reamer, which can extend radially to enlarge the borehole beyond the drillbit diameter, utilizing drilling mud pressure or mechanical means for actuation, and employing individual driving systems like hydraulic or electric motors to reduce torque and enhance drilling efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If passive cutters (blades or rollers) are used to enlarge the borehole, then the borehole diameter can be increased, but the drillstring torque increases significantly

Engineering Contradiction:

Improveborehole diameterVSAvoiddrillstring torque

Core Design Contradiction:

Area of stationary objectVSForce

Solution Approach 1:

The side cutters are equipped with individual driving systems (hydraulic motors or electric motors) that enable them to rotate independently and self-propel along the borehole wall. This self-service capability allows the cutters to actively engage and remove material without requiring excessive torque from the main drillstring, thereby increasing borehole diameter while maintaining acceptable torque levels.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The cutting function is segmented into multiple independent side cutters, each with its own driving system. Instead of relying on a single large torque source to drive all cutters, each cutter operates independently with its own motor, distributing the torque requirement and enabling more efficient material removal along the borehole circumference.

Inventive Principle:

Principle #1Segmentation

2Area of stationary object

If passive cutters are used to ream the borehole, then the borehole diameter can be enlarged, but vibration increases limiting the maximum achievable diameter

Engineering Contradiction:

Improveborehole diameterVSAvoidvibration

Core Design Contradiction:

Area of stationary objectVSStability of the object's composition

Solution Approach 1:

The self-rotating side cutters with individual motors can actively adapt to borehole conditions and maintain stable cutting engagement. They can independently adjust their rotation and positioning, which helps dampen vibrations and maintain stable operation during borehole enlargement, enabling larger diameters to be achieved without excessive vibration.

Inventive Principle:

Principle #25Self-service

3Force

If active rotary cutters with individual driving systems are used, then torque and vibration are reduced, but the device complexity increases

Engineering Contradiction:

Improvedrillstring torqueVSAvoiddevice complexity

Core Design Contradiction:

ForceVSDevice complexity

Solution Approach 1:

The patent replaces the traditional passive mechanical cutter system with active rotary cutters powered by individual hydraulic motors or electric motors. This substitution of mechanical systems with powered units enables independent rotation of each cutter, reducing the torque burden on the drillstring while managing the inherent complexity through modular design.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention utilizes hydraulic motors to power the individual side cutters, replacing purely mechanical drive systems. The hydraulic system allows for flexible power distribution to multiple independent cutters, enabling reduced drillstring torque while managing system complexity through fluid power transmission rather than complex mechanical gearings.

Inventive Principle:

Principle #29Pneumatics and hydraulics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution allows for larger borehole diameters with reduced drillstring torque and vibration, enabling more efficient drilling by using active rotary cutters that can rotate independently and extend radially to engage the borehole walls effectively.

Implementation Method 1

the side cutters are adapted to be rotated independent of the reamer housing around an axis that is not parallel with the axis of rotation of said drillstring

Methodology Applied

Scientific EffectIndependent rotation:

Implementation Method 2

employing a self driven rotational side cutter to extend radially outward from a body of the reamer

Methodology Applied

Scientific EffectRadial extension:

Data Source

PatentUS8789624B2Cutting tool integrated in a drillstring

Publication Date: 2014.07.29 SINVENT AS

AI summary

The present invention discloses a cutting tool integrated in a drillstring for enlarging a borehole, where the cutting tool at least comprises: one or more side mills (12, 13, 14) arranged along the axis of said drillstring in a reamer housing (11), where the side mills (12, 13,14) are adapted to be rotated relative to the tool housing (11) by individual driving means. The self driven rotational side mills may be dome shaped cones where expand radially out of the reamer housing (11), or may be a special non-circular dome shaped cones where rotates without expanding.