Drill Bit Backup Cutting Elements for Hard Formation Penetration

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Solution Overview

Problem

Conventional drill bits are limited in their ability to effectively penetrate various types of rock formations, with roller cone drill bits performing well in hard formations and fixed-cutter bits in soft to medium hardness formations, leaving a need for a drill bit that can efficiently drill through a range of rock types.

Innovation Solution

A drill bit design featuring primary cutting elements and backup cutting elements with distinct cutting characteristics, such as different backrake angles, siderake angles, cutting element sizes, and exposures, arranged in specific configurations to engage the rock surface after primary cutting element wear, enhancing the bit's penetration capabilities across diverse formations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If roller cone drill bits with tungsten carbide insert cutting structures are used, then rate of penetration and lifetime in hard and superhard formations are improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improverate of penetrationVSAvoiddevice complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The drill bit is divided into multiple functional groups: primary cutting elements for initial penetration, backup cutting elements for sustained cutting after primary element wear, and reamer elements for hole cleaning. This segmentation allows each element to be optimized for its specific function while collectively providing both high penetration rate and durability in hard formations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different cutting elements are assigned different cutting characteristics tailored to their specific functions and positions. Primary cutting elements have characteristics optimized for initial penetration, while backup elements have characteristics optimized for sustained cutting. This local optimization of cutting characteristics resolves the contradiction between penetration rate and durability.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If fixed-cutter drill bits are used, then ease of operation in soft to medium hardness formations is improved, but productivity in hard and superhard formations deteriorates

Engineering Contradiction:

Improveease of operationVSAvoidrate of penetration

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The drill bit combines multiple cutting mechanisms (abrasion, fracturing, shearing) and multiple cutting element types (primary, backup, reamer) into a single versatile tool that can effectively handle a wide range of formation hardnesses, from soft to superhard, eliminating the need to switch between different bit types.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The drill bit incorporates varying cutting characteristics among different cutting elements, including different geometries, material hardnesses, and wear properties. This parameter variation allows the same bit to adapt its cutting behavior to match the hardness of the formation being drilled, providing both ease of operation and high productivity across diverse formations.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional single-characteristic cutting elements are used, then device complexity is reduced, but adaptability to various rock formation types deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidadaptability to rock formations

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

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

The drill bit achieves improved rate of penetration and durability, capable of drilling through hard and superhard formations where conventional fixed-cutter bits typically fail, by utilizing backup cutting elements with varied characteristics to maintain effective cutting performance.

Implementation Method 1

Various removal mechanisms can be used to advance the depth of the borehole including abrasion, fracturing, and shearing the subterranean formations at the bottom of the borehole

Methodology Applied

Scientific EffectAbrasion: Abrasion

Implementation Method 2

Roller cone drill bits typically advance through contacted subterranean formations through fracturing and abrading mechanisms

Methodology Applied

Scientific EffectFracturing: Fracture Mechanics

Implementation Method 3

Fixed-cutter drill bits, by contrast, employ cutting elements made of hard material that are situated on the drill bit in a manner to shear and cut through contacted rock formations

Methodology Applied

Scientific EffectShearing: Shear Stress

Data Source

PatentUS8887839B2Drill bit for use in drilling subterranean formations

Publication Date: 2014.11.18 BAKER HUGHES CO

AI summary

A drill bit for drilling subterranean formations comprising a drill bit body including a group of primary cutting elements comprising a first primary cutting element and a second primary cutting element radially spaced apart from each other along a first radial axis. The drill bit body further including a group of backup cutting elements comprising a first backup cutting element in a secondary cutting position relative to the first primary cutting element and a second backup cutting element in secondary cutting positions relative to the second primary cutting element, wherein the first and second backup cutting elements are radially spaced apart from each other along a second radial axis different than the first radial axis and comprise a difference in cutting characteristic relative to each other of one of a backrake angle and a siderake angle.