Drill Bit Blade Sweep Zone Reduces Rubbing

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Solution Overview

Problem

Drill bits experience reduced rate of penetration due to excessive rubbing contact with subterranean formations and suffer from instability caused by bit whirl, leading to damage to cutting elements, particularly at higher rotational speeds.

Innovation Solution

The implementation of a controlled or engineered rubbing surface on the blade face of the drill bit, featuring a sweep zone that rotationally trails the contact zone, reduces rubbing contact and enhances stability by distributing the weight-on-bit effectively, thereby minimizing lateral motion and impact stresses on cutting elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If rotational speed of the drill bit is increased to increase rate of penetration, then productivity is improved, but rubbing contact between blade face surface and formation increases causing instability and cutting element damage

Engineering Contradiction:

Improverate of penetrationVSAvoidcutting element stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The blade face surface is segmented into distinct functional zones: a contact zone for primary cutting engagement and a sweep zone for reduced rubbing contact. This segmentation allows the drill bit to achieve high rate of penetration through aggressive cutting elements in the contact zone while the sweep zone minimizes instability and rubbing contact at higher rotational speeds.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the blade face surface are given different properties: the contact zone features aggressive cutting elements for maximum material removal, while the sweep zone has a configuration that reduces rubbing contact. This local differentiation resolves the contradiction by allowing high productivity in the contact zone while maintaining reliability through reduced rubbing in the sweep zone.

Inventive Principle:

Principle #3Local quality

2Productivity

If aggressive cutter placement and orientation is used to increase rate of penetration, then productivity is improved, but bit whirl and lateral instability increase causing cutting element damage

Engineering Contradiction:

Improverate of penetrationVSAvoidbit rotational stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The blade structure is segmented into a contact zone with aggressive cutting elements for high rate of penetration and a sweep zone that provides structural support and stability. This segmentation allows the bit to maintain aggressive cutting performance while reducing lateral instability and bit whirl through the stabilizing sweep zone.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The blade face surface configuration creates an asymmetric distribution of cutting elements and sweep zones that optimizes both cutting aggressiveness and rotational stability. The asymmetric placement allows aggressive cutters in the contact zone while the sweep zone geometry counteracts lateral forces that cause bit whirl.

Inventive Principle:

Principle #4Asymmetry

3Quantity of substance

If rubbing contact area is increased to improve hydraulic flow, then fluid flow efficiency is improved, but rate of penetration decreases due to excessive rubbing

Engineering Contradiction:

Improvehydraulic flow volumeVSAvoidrate of penetration

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The blade face surface is segmented into a contact zone that maintains adequate hydraulic flow paths and a sweep zone that reduces rubbing contact. This segmentation allows the drill bit to achieve high rate of penetration by minimizing rubbing in the sweep zone while preserving sufficient hydraulic flow capacity in the contact zone for effective cuttings removal.

Inventive Principle:

Principle #1Segmentation

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 design allows for increased rate of penetration while maintaining stability, as the sweep zone reduces the extent of rubbing contact and mitigates the effects of bit whirl, protecting cutting elements and improving hydraulic flow efficiency.

Implementation Method 1

rubbing contact occurs between a face surface, particularly, the face surface of a blade of the drill bit coming in contact with a bottom hole, or drilling portion of a subterranean formation

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

Radially directed centrifugal imbalance forces exist to some extent in every rotating drill bit and drill string

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 3

impact loads caused by vibrational instabilities commensurate with bit whirl

Methodology Applied

Scientific EffectVibration: Vibration

Data Source

PatentUS7836979B2Drill bits and tools for subterranean drilling

Publication Date: 2010.11.23 BAKER HUGHES CO

AI summary

A drill bit having a bit body includes a blade face surface on at least one blade extending longitudinally and radially outward over a face of the bit body. The blade face surface of the at least one blade includes a contact zone and a sweep zone. The sweep zone rotationally trails the contact zone with respect to a direction of intended bit rotation about a longitudinal axis of the bit body provides reduce rubbing contact when engaging with a subterranean formation.