Rock Failure Mechanisms and PDC bit

8/11/2019 Rock Failure Mechanisms and PDC bit

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TP ON DU KH VIT NAMTRNG I HC DU KH VIT NAM

Group 10

ROCK FAILURE MECHANISMS & PDC

Dr. Nguyen Van Hung


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Rock Failure MechanismsDrilling Engineering

M

1. Nguyen Quang Khai

2. Doan Nguyen Minh Son

3. Vu Xuan Van

4. Nguyen Xuan Tan Binh


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1. Oil & gas drill bits overview

2.The Mohr criterion

3. Rock failure mechanisms

4. PDC bit


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Oil & gas drill bits o

Video


5/25Rock Failure MechanismsDrilling Engineering

The Mohr

=1

1+ 3

1

1 3 cos 2 (1)

=1

1 3 sin 2 (2)

+ 2 = 90 (3)



The Mohr criterion-

Problem:

A rock sample under a 2,000-psi confining pressure fails w

subjected to a compressional loading of 10,000 psi along a

makes an angle of 27with the direction of the compressio

Using the Mohr failure criterion, determine the angle of inte

the shear strength, and the cohesive resistance of the mate



The Mohr criterion-

Solution:

The angles and 2must sum to 90. Thus, the angle of i

friction is given by

= 90-2(27)=36.

The shear strength is computed using Eq (2) as follow= 1/2(10,000-2,000) sin(54)=3,236.



The Mohr criterion-

Solution:

The stress normal to the fracture plane is computed usi

Eq (1) as follows.

=1/2(10,000+2,000)- 1/2(10,000-2,000)cos(54)=3,6

The cohesive resistance can be computed by rearrangin

tangential line Eq as follows.c= tan

=3,236-3,649tan(36)

= 585 psi.



Rock failure mec

Basic mechanisms of rock removal:

1 Wedging

2 Scraping and grinding

3 Erosion

4 Percussion or crushing



Rock failure mec



Cutters are expected to endure throughout the life of a b


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PDC bits drill primarily by shearing


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PDC cutters are set into bits to achieve specific rake (atta

relative to the formation.

This angle contributes to bit performance by:

Influencing cleaning efficiency.

Increasing bit aggressiveness.

Prolonging cutter life.


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-The tendency for cuttings tostick to the bit face is reduced

-Reduce depth of cut and,thus, ROP and bit vibration

-Increases cutter life

-Aggressiveness, depth of cutand ROP are increased

-To maximize ROP when softerformations are drilled

Increase

rake angle

Decrease

rake angle


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Factors affecting bit design and performanc

Mechanical design parameters

Materials

Hydraulic conditions

Properties of the rock being drilled


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Hybrid drill bit


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S


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S

1. Oil & gas drill bits overview: Roller-cone bit and Fixed-c

2. The Mohr criterion: The Mohr criterion, Problem and so

3. Rock failure mechanisms:

4. PDC bit: Properties and Hybrid drill bit

Re


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Re

http://petrowiki.org

http://youtube.com

Baker Hughes

Adam T.Bourgoyne Jr, Keith K.Millheim, Martin E.Chenev

Young Jr, Applied Drilling Engineering

PGS.TS L

PhcHo

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khoan khai thcdu

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Future st


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Future st

Study the Mohr criterion deeply

Study Rock failure mechanisms

Giving a subtitle to the recommended videos


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Rock Failure Mechanisms and PDC bit