Chapter 13 Tnpptng i'rauiccs

Wiper Trips Wiper trips are often required to condition the well, but unnecessGlY trips can be detrimental to well bore stability. Wiper trips are required to wipe away thick filter cakes and swelling clays. They are also useful for reaming away ledges and taking the rough edges off of small doglegs. Wiper trips can also tell us a lot about the condition of hole that was recently drilled. For these reasons, rig hands like to make regular wiper trips.

Wiper trips take time and can be detrimental. Therefore, design engineers and drilling optimizers tend to discourage them. A balance must be struck. The hole can dictate when a wiper trip is required, but only to experienced drilling hands who recognize the trends and have regional experience.

Attempting to save time on a well by minimizing wiper trips can result in stuck pipe. Likewise, unnecessary trips can result in stuck pipe.

Well Bore Instability Well bore stability is compromised while tripping due to the fluctuating stress distribution around the well bore caused by:

High side loads imparted by the drill pipe across doglegs when the weight on bit goes to zero

The temperature fluctuations when circulation is stopped

Surging and swabbing

The axial loads caused by the drill string dragging along the wall

Fluid loss in shale due to longer open hole exposure time

Well bore stability can be monitored with pressure and drag trends while tripping. lfthe well is relatively unstable, it may take longer to make a wiper trip than it took to drill the section. Patience is required. Ideally, as little energy as possible will be imparted to the well bore walls while tripping out. We must also get back to bottom and circulate quickly in order to minimize open whole exposure time and temperature fluctuations .

On deeper wells, it may be necessary to stage our way into the well in order to minimize pressure and temperature surges. The thixotropic qualities of the mud cause it to thicken when it is static. A pressure surge occurs when circulation is started. The pressure drops as the viscosity quickly returns to nornlal.

The lower portion of the well will heat up when cool mud is no longer circulated across it, and the upper portion of a deep well may cool down when wann mud is no longer circulated past it. The mud in tbe tanks also cools while circulation is stopped. Then when circulation is started again, the cool mud sweeps across the warmer fOffilations, and hot mud sweeps past the cooler fOmlations at the top. It takes time to get the fOmlations back to nOmlal circulating temperatures. Some well bore caving or lost circulation may occur during these temperature changes. (See Fig 8-106)

254 t Copynght 2()O I, I 'nglllccnng. In,:

Chapter 13 Tnpping Practll'\!S

Differential Sticking If differential sticking is a concern, we must pay very close attention to the first few stands stood back. Contrary to popular belief, most differential sticking occurs in the drill pipe high in the bole, not around the collars down lower in the hole. I This is largely due to the high side load the drill pipe applies to the well bore wall when the bit is off bottom. It may also be due to high wall contact due to minor keyseating of the pipe against the high side of the hole. (See chapter 9, Figures 9-13 and 9-19.)

lfwe have doglegs througb an under-balanced sand, we should be particularly careful. We must keep the pipe moving as much as possible. We may need to condition the mud with lubricants prior to tripping out.

When tripping back in, we may not notice mucb trouble with differential sticking as the collars first pass the sand. However, as more and more weight hangs beneath the pipe against the sand, the side load against it increases. We may become stuck just a few stands off bottom, even though the collars are not against a sand formation.

Note also that the static filter cake will be very thick when we are tripping back into the well. It may be prudent to stop and circulate to condition the ftlter cake before continuing to trip to bottom.

Circulating After the Trip Tbe trip begins when drilling has stopped and circulation begins to condition the well and mud. Tbe trip doesn't end until the bit or casing is on bottom and tbe well bas been circulated to condition the well and mud.

Circulation to condition the well after the bit is back on bottom cannot be taken lightly. Trip gas will come to surface sometime before bottoms up strokes. The lag time between maximum trip gas and bottoms up stroke can provide valuable insigbt into migration speeds and/or the origin of the gas. Tbe gas expands as it nears the surface and can cause the well to go under-balanced. It may be necessary to circulate the last half(or fourth) oftbe bottoms up on the choke.

As well bore temperatures stabilize, some caving and partial losses can occur. We don ' t want to start drilling or cementing casing until these problems have stabilized.

255 "( l('p~nglll ~IJ(lI. Drilbt.:n I f1glnt"l.nng Inc

Chapter 13 I ripping Pnll.:ticcs

Bibliography

I) Stewan, Maurice I. Jr., U.S. Minerals Management Service, Metaire, LA: "A MetllOd or Selecting Casing Setling Depths to Prevent Differential-Pressure Pipe Sticking"

256 I Cnp~Tighl 200 I. nrilh~n I ngllll'L-rillg Ill\..

Conclusion

The title of this book is Trouble-free Drilling. As the name implies, it is intended to be a guide for drilling trouble-free.

The focus of this book has been primarily on the mechanics of stuck pipe. This is because stuck pipe accounts for the vast majority of down hole problems. There are other problems however, such as drill string failure, lost circulation, slow drilling, directional control , and well control. Recently, we have had to add "deep water" problems and high pressure/high temperature issues as well .

It was my intention to address those issues in this book. However, I feel the need to get the material on stuck pipe to the presses now. I intend to add the other chapters later, or in additional volumes.

One point I want to stress is that it is the men on tbe rig wbo drill tbe well and are best positioned to monitor and deal witb the problems tbey encounter. They must be knowledgeable about these problems and properly trained to deal with them if we are to drill trouble-free. I cannot say this often enough, "all the understanding the drilling industrY has acquired over the past century is of no use if it does not reach the man on the ri g."

This book was written for the drillers, tool pushers, drilling foreman, and engineers who actually drill the wells. Hopefully, this manual will find its way into their hands, where they can use it to increase their understanding of down hole mechanics.

I am currently preparing additional chapters for a second edition of this manual. I welcome comments, challenges. criticism, and questions pertaining to any of the material presented thus far. I also welcome additional source material and comments for existing or future material presented in the second edition.

I can be contacted at my international drilling school and consulting firm via my e-mail address. DriIbert@aol.com.

I will end this book with one final thought;

Just as in the game of chess, one can improve his game substantially by reading and studying books on the subject. But studying alone does not help a chess player become great- he needs practical. on the board, experience. Then he must carefully analyze this experience with his peers and trained instructors. Without professional training and formal endgame analysis, a chess player never moves beyond the rank of novice. The same is true for drillers and drilling supervisors.

Regards,

John Mitchell President Drilbert Engineering Inc.

257

Appendix A Hole Cleaning Charts (for wells with full pipe rotation)

Procedures for using the hole cleaning charts from lADC/SPE paper 27486 "Simple Charts to Determine Hole Cleaning Requirements"

I . Select one of the three hole sizes: 17 Y2" 12~" 8 Yi"

2. Enter the appropriate Rheology Factor chart. (tbe ones on the left) Using Plastic Viscosity and Yield Point values, read off the value ofthe rheology factor, RF.

3. Get the Angle Factor, AF, from Table 1.

Table 1 An Ie Factor fo r Deviated Holes Hole An Ie de An Ie Factors

25 1.51 30 1.39 35 1.31 40 1.24 45 1.18 50 1.14 55 1.10 60 1.07 65 1.05

70-80 1.02 80-90 1.0

@SPE

4. Calcu late the Transport Index, Tl, using the following equation:

TI = RFxAFxMW

Where: TI = Transport Ratio

RF = Rheology Factor from the hole cleaning charts

MW = Mud weight in specific gravity

Note: Specific gravity refers to the weight of mud relative to the weight of fresh water. To convert mud weight to specific gravity, divide it by 8.33 Ibs/bbl, or use the following equation:

TI = RF x AF x MW.;. 8.33 Where: TI = Transport Ratio

RF = Rheology Factor from the hole cleaning charts

MW = Mud weight in Ibslgallon

5. Use the calculated Transport Index in the charts on the right to find either the minimum flow rate for a desired penetration rate, or the maximum rate of penetration for a particular flow rate.

259 ,I CnJ'lyrighl 200 I Orilht.:r1 I n!!Jnt'crinl.! Int.'

50

45 0 .8

Il.

" 40 ~ 'in 35 0

" 30 " ~ '"

25

a: 20

20

45

40

Il.

" 35 0 .8

~ 0.9 'in 30 0

III :> 25 " "ti '"

20

a: 15

15

40

35 Il.

" 30 ~ 'in 0 25 " 20 " ~ 15 11 '" a:

10

5 10

@SPE

Hole Cleaning Charts for 17 W' Holes

140

_,30 1.2 1.3 E 1 4 "'120 S 1.5 .!!l'10 OJ 1.6 cr: 1.7

1.1 ;: 100 0 18 u: / 900 1.9 " 12 :J _ 2.0 ::!

Rheology 800 Transport Faclor 2.1 Index

25 30 35 40 45 50 0 5 10 15 20 25 30 35 40

Yield Point (lbI1 00 tt") Rate of Penetration (mlhr)

Hole Cleaning Charts for 12 14" Holes

1000 I

) 0.9 1.0 TI 0.9 '[900 1.2 ~ 1.3 '" iii 800 1.4 cr: ;: 1 5

1.25 .Q 700 "- 1.

1.3 " 1.7 :J 1.8 ::!600 1.9

Rheology 2.0 Factor 2,1

20 25 30 35 40 45 0 5 10 15 20 25 30

Yield Point (lb/ l00 ft2) Rate of Penetration (m/hr)

Hole Cleaning Charts for 8 W' Holes

0.9 1.0 1.0

J

12

/

~12

~Ology Facto(

, 15 20 25 30 35

Yield Point (Ib/l 00 ft2)

40

260

500 ,-----------~~------~~_,

475

'[ 450 Cl

'; 425

~ 400 ~ 375 u: " 350 :J ::! 325

1 ,

1,2

1.3

1.4

1.5 1.6

1,7 1.8 1.9 2,0

2 ,1 Transpon Index

~ +-~_r~~~~r_--,---_r--~

o 5 10 15 20 25 30 Rate of Penetration (mlhr)

.( Copynghl ::!OOI. ()rilb(:rt I ,ng.lI1l'enng 11ll.'.

Example: Assume a horizontalS \1," hole witb 12 ppg mud, a PV of25 cP, and a yP of IS lb/ IOO ft2.

Question: What is the maximum rate of penetration we can achieve with 450 gpm flow rate?

Answer: From the RF cbart, for S\I," bole, we find that the RF = 0.91 From Table 1, we find the Angle Factor, AF = 1.0 The Transport Index, TI, is calcu lated to be:

Tl = RF x AF x MW -;- S.33 TI = 0.91 x 1.0 x 12 -;- S.33 = 1.31

From the ROP chart, for S\I," hole, at a Tl of 1.31 and a flow rate of 450 gpm we can bave a maximum ROP of about 23 meters per hour.

Question: What is the minimum flow rate we need to drill at a rate of penetration of 20 meters per hour ?

Answer: From the ROP chart, for S \1," bole, at the TI of 1.31 calculated above, and a ROP of 20 m/br, we find we need a flow rate of 440 gpm.

261 ( lory-righl 20111 . Dnlbcrt 1'llgl11t:cnng illl:.

Appendix B Equations

Kirsch produced equations for determining the stress distrihution around a circular tunnel in 1898. A full discussion on the derivation of these equations is given by Jaeger and Cook.s The equations are summarized below.

Kirsch Equations

Stress components at point fr.St Radial a, ~ Yzoz{(1 + k)(J -a /~) + (I - k)( I - 4a'/~ + 3a4/r4)Cos2B} Hoop 00 ~ Yzoz 1 + k)(1 + a'/~) - (I - k)(1 + 3a4/r4)Cos2B} Shear'tril ~ Yzoz(-(I - k)(1 + 2a'/~) - 3a4/r4)Sin2B}

Principal stresses in plane of paper at point (r.B) Maximum 0\ ~ Yz(o, + ( 0) + (l4(0, - ( 0)' + 'tril')' Minimum 02 ~ Yz(o, + oe) - (l4(0, - (0)' + 't"")~

Kirsch Equations Horizontal --.. Stress _

Vertical Stress

l oo 9

t Fig B-1 Kirsch equations for wellbore stress

'tre 0,

r ....

Note: These equations are for a horizontal tunnel. They work exactly as printed for horizontal wells. For vertical wells, the vertical stress must be substituted for the major horizontal stress, and the horizontal stress must be substituted for the minor horizontal stress.

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Table of Figures

Fig 1-1 The chain of events leading to unscheduled events ......... ...... ...... .......................................... 11 Fig 2-1 Reckless risk taking ................................................ .. ..................... ................... ... .................. 13 Fig 3-1 Morale barometer ................................................................................................................... 20 Fig 3-2 Bottom-up communication ......... ....... ............. ......... ............................ .................................. 20 Fig 4-1. Problem Solving ......................................................... ........................................................ .. 24 Fig 5-1 Mud weight window .............................................................................................................. 31 Fig 5-2 Bit stabilization ....................................................................... ............... .............. ... ........... .... 33 Fig 7-1 Momentum ... ............... ... ... ... ............................... ...... ....... ..... ........ ................................ ...... ... 44 Fig 7-2 Laminar flow profile ........................................................... ... ............................... ................. 45 Fig 7-3 Cuttings migration ................................ .. ................................................ ..... ........ ......... .. ....... 45 Fig 7-4 Cuttings recycling ....................... ... .................... .... ...... .......... ................................................ 46 Fig 7-5 Flat flow profile ...................................................... ..... ........................................... ........... .... 46 Fig 7-6 Flow rate vs. p ressure ........................................................................................................... 47 Fig 7-7 Flow regimes ....................... ....... ................................ .................. ... ..... .. ..... ..... ....... .. ............. 47 Fig 7-8 Yield Point ................................................................. ........................................... ......... ........ 48 Fig 7-9 Carrying capacity ....................... .................... ............. ... ..... .................................................. .49 Fig 7-10 Consistency curves for typical fluids .................................................. .................. ............... 50 Fig7-11 Surface area of cuttings ....................................................................................... .. .... ...... .... 51 Fig 7-12 Plastic viscosity ....... .......... ................................................................................................ .. 51 Fig 7-13 Apparent viscosity vs. shear rate .................................................................... .............. ....... 52 Fig 7-14 Graphical determination ofYP and PV ............................................................................... 54 Fig 7-15 Excessive solids deform the flow profile ............................................................................. 55 Fig 7-16 Pipe rotation Fig 7-17 Pipe eccentricity ...................................................................... 56 Fig 7-18 Slip velocity in inclined wells ............................................................ ... ............................... 57 Fig 7-19 Three regions of inclination ........................................ ......... .. ........ .... .......... ........................ 58 Fig 7-20 Cuttings concentration climbs rapidly after 30 .................................................................. 59 Fig 7-21 Boycott settling Fig 7-22 Boycott settling .............. ... ........ .. ................. ... .................... 60 Fig 7-23 Cuttings transport at various inclination angles ............. .... .. ................................................ 61 Fig 7-24 Asymmetrical flow profile ......................................... .. ........................................................ 62 Fig 7-25 Effect of mud weight on cuttings bed height.. ..................................................................... 63 Fig 7-26 Velocity profiles in a horizontal well ...... ........ .. .. ................................................................ 64 Fig 7-27 Effect of viscosity on cuttings bed height... .................................................... ......... .... ... ..... 65 Fig 7-28 Shear rate ................... ... ... ........................................................... ..... .. .................................. 67 Fig 7-29 Velocity threshold .......................................... .................................... .................................. 68 Fig 7-30 The effect of velocity on cuttings bed height ...................................................................... 69 Fig 7-31 Equilibrium bed height .............................................................. .. ........................................ 70 Fig 7-32 Critical bed height. ................................ ...... ............. ... .. ....................................................... 70 Fig 7-33 Critical cuttings bed height ................................................ ... ....... ..... ................................... 71 Fig 7-34 Critical cuttings bed height ............................. ......... ............................................................ 71 Fig 7-35 Cuttings bed height vs. surface volume .................... .... .......................... ................ ............. 72 Fig 7-36 Three distinct regions of cuttings beds ............ .. .................................................................. 73 Fig 7-37 Cuttings transportation .................................... .............. .......................... .......... ................... 74 Fig 7-38 Cuttings transportation ............... ........ ... ............................................................. .................. 74 Fig 7-39 Bed transportation .................................................................................................... .. ....... ... 75 Fig 7-40 Typical cuttings transportation in high angle wells .............. .... .......... ............................. .... 75

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Fig 7-41 Annular velocity vs. hole angle .......... ... ... .. .... ... ......... ... ........ ... ............ ................... ........ .. .. 76 Fig 7-42 Effect of pipe eccentricity on cuttings beds .................... ..................................................... 78 Fig 7-43 Threshold RPM .. ....... ... ... ..... ... ........... ........ .... ........ ... ... ... ... ... ..... .. ...... .................... .......... .... 79 Fig 7-44 PWD data and hole cleaning ............................... ........... ............................................... ...... . 79 Fig 7-45 Coi led tubing drilling .. ..... .. ....................................... .. ............... ........ .................................. 8 1 Fig 7-46 Circulating time .................... ...... .......... ... ..... .. .... .... .............. ... ... .... ...... ..... .......... .......... ...... 82 Fig 7-47 Boyles law ................ .. .. ... ... ... .. ... .......... ....................... ........................................................ 83 Fig 7-48 Effect of compressibility on annular velocity ................... ........... ........................................ 84 Fig 7-49 Optimum annular velocity ..... ... ............. .............................................................................. 85 Fig 7-50 Specific area of cuttings ........................................ ... ........ ................................................ ... . 86 Fig 7-51 Standpipe pressure vs. bottom hole pressure .. .... .... .. .................. ... ......... .... ................ ......... 88 Fig 7-52 Slugging ....... ... ........................................ ......... ...... ... ... ......... ........ ........................................ 89 Fig 7-53 Foam quality .... .... .. ........... ........ ........... ...... ........... ............................................................... 90 Fig 7-54 Foam viscosity .... .............................................................................................................. ... 91 Fig 7-55 Annular velocity vs. depth .................................. ......... ........... ................................ ............. 92 Fig 7-56 Air vs. foam .................................................. ........................ ........ ... ........ ........ ..... ..... .......... 93 Fig 7-57 Packoff ...... .............. ... .... .... ... ........ ...... ... .. ............. ...... ... .. .... ... .... ....... .. ... ... ... .... ...... ...... .... ... 95 Fig 7-58 Packoffs in doglegs ............... ......................................................................... ...................... 97 Fig 7-59 Geolograph trends for poor hole cleaning ........................................................................... 99 Fig 8-1 Shale formation .... .............................. ... ... ...... ............ ........... ... ... ..... .................................. .. 105 Fig 8-2 Shale formation .. ... ........... ......... .......... ............... ........... ............ .......... ........................ ........ . 106 Fig 8-3 Dispersion .. ........ ....... .... .. ..... ................... ............. .. ... ....... .......... .... ... ..... ... ..... .... ....... ... ........ 107 Fig 8-4 Rock strength ...... ..... ........ .... ...................... .. ............... .. ........ ... ..... ......... ........... ................... I 08 Fig 8-5 Apparent rock strength .......... ..................... .... ....... ............ ........ ......... ... .. ............................ 109 Fig 8-6 Rock strength ........................... .. ............................................. .... .................. .. ..................... 110 Fig 8-7 Rock strength analogy ... ..... ........ ... ...................................................................................... III Fig 8-8 Stress states ....... .. .................. ..... ............ .............................................................................. 112 Fig 8-9 Effective stress and pore pressure ... ......... .................... .. ................ ...................................... 113 Fig 8-10 Stress-strain relationship ....... ................ ............... ......... ...................... ............................... 114 Fig 8-12 Poisson's ratio ................ ... ..... .......... ... ... ............. ... ........ ........ ..... ......... ............. ....... ... ..... .. 115 Fig 8-13 Brittle vs. ductile behavior ..................... .. ......... .. ............... .... .... ............................. .. ......... 115 Fig 8-14 Three-dimensional stress state ..... .... ............... ...................... .. .... .. .. ................ ................... I 16 Fig 8-15 Major and minor stresses .............. ....... ................ ... ........................................................... 116 Fig 8-16 Well bore stresses .... .. ...... ................................................................................................. . I 17 Fig 8-17 Well bore stress components ............... .. ...................... .. ......... .. ......................................... 117 Fig 8-18 Stress In-Situ ....... ............. .... .. ............... ... .................... ....... ................................. ..... ....... ... 118 Fig 8-19 Stress in the well bore wall ................................................................................................ 119 Fig 8-20 Hoop stress ........... ............................................... ... .... .......... .... ... .. ................ .................. ... 120 Fig 8-21 Hoop stress ...... .... .... ... ................................ ...... .... .............. ......... .. ... ... .......... .......... ........... 120 Fig 8-22 Stress field-distribution around the well bore ..... ..... ....... .. .. .... .......... .. .. .... ... .. ........... .. ....... 121 Fig 8-23 Hoop stress around the well bore .................................. ...... ....... .. ...... ... ...... .. ..................... 121 Fig 8-24 Anisotropic stress distribution ........................................................................................... 122 Fig 8-25 Hoop stress away from the wall .... .... .. .... .................. ............ .. .... .. ..................................... 123 Fig 8-26 Stress stream lines3 ....................... ... ... ....... .................. .. .......... .......................................... 123 Fig 8-27 Stress contours3 ...... ........ ......... ............................ .. ... ... .. .... ... ... ..... ................ ...................... 124 Fig 8-27 Stress contours (continued) .. ... ....... ...... .......................... .... ........ .. ........ ... ....... ................ .... 125 Fig 8-28 Stress redistribution ..... ... ............ ... ...................................................... ......... ... .... .. ........ .... 127 Fig 8-29 Radial stress .... ... ........ ... .. ................ .... .. .... ........ .......................... ... ..... ........ ..... ... ....... ..... .... 127 Fig 8-30 Relationship between radial and hoop stress .............. .. ....... .. .. .. ................. ... .......... ... ..... .. 127

266

Fig 8-31 Axial stress along well bore .......... ..... ............ .................. ..... .. .... ............. ..... ................. .... 128 Fig 8-32 Tri-axial stress along well bore ..... .. ...... .. .. .. ... .. .. .... ............................................ ... ... ......... . 128 Fig 8-33 Mohr's Circle .............................................................................. ................. ......... ......... ... . 129 Fig 8-34 State of stress on a plane .............................................................. ................ .. ... .... .... .... .... . 130 Fig 8-35 Mohr's failure envelope ...................... .............. ......... .... .. .... .. ...... ...................................... 131 Fig 8-36 Stress redistribution ............... ... ..... ... ... ...................... .......... ..... ... ....... ............ ..... .. .. ... ....... 132 Fig 8-37 Radial stress ... ........................... ...... ........... ... ........ ..... ... .. .......... ... ...................................... 132 Fig 8-38 Relationship between radial and hoop stress .. ................ ................................................... 133 Fig 8-39 Mohr's failure envelope for mud weight .................. ......................................................... 133 Fig 8-40 Lost circulation and caving ............................... ...... .... ...... .. ............... .. ...... ............. .... .... ... 134 Fig 8-41 Lost circulation and caving ..................................................... .. ........ ........ ......................... 134 Fig 8-42 Rock strength ....................................... .......... ......... ... .. ..... .................. ................... .. ... ....... 135 Fig 8-43 Depth vs. penetration rate plot.. ........................................................................... .............. 135 Fig 8-44 Earth's temperature gradient... ... ........................................................................................ 136 Fig 8-45 Mohr's failure envelope for temperature changes ............................................................. 137 Fig 8-46 Stress regimes ... ... .. .... ... .. .......... .. ......... .... .......................... ......... ................. ...... ................ 138 Fig 8-47 Stress anisotropy .. .... .... ... ........................................ ... .. .................. .................................... 139 Fig 8-48 Stress anisotropy ... ........ ... ........... ... .... .. ................... ... ..... ................................................... 139 Fig 8-49 Normal fault stress regime .......... .... .... .. .. .................... ................... .. .. .......... ...... ....... .... .. ... 140 Fig 8-50 Strike slip faulting stress regime .... .................................................................................... 141 Fig 8-51 Reverse faulting stress regime ........................................................................................... 142 Fig 8-52 Hydrational stress in bedding planes .................. .. .................................... .. ....................... 143 Fig 8-53 Bedding plane strength .......................... ............................................................................ 144 Fig 8-54 Pore pressure vs. time ................ .. .................... .. .......... .. .. ..... ................. .... .. ......... .. ... ........ 146 Fig 8-55 Drawdown curve Fig 8-56 Injection curve ................................................................ 147 Fig 8-57 Mohr's stability envelope for filtrate invasion ...... ...... ........ .................. .. .......................... 148 Fig 8-58 Filtrate invasion with respect to time .. ............................ ............................................ ....... 149 Fig 8-59 Filter cakes on shale ................ .. .................... ......... ........... .... .................. .... .... ................... 150 Fig 8-60 Shale permeability ....... ...... .. .. .. ..... ... ...... .. ... ...... ........... ....... ..... ......... ............. ...... .............. 151 Fig 8-61 Osmotic flow in shale .......................... .. .................... .. ........ .............................................. 15I Fig 8-62 Capillary action ........ .. ....................... ... .. ... ... ................. ..... .. .......... .. ............. ....... ........ ...... 152 Fig 8-63 Drill string vibration ...... .. .............................. ........................................ .. .......................... 153 Fig 8-64 Failure modes ... ........ ......................... ........... ........ ............. ........ .......... ............ ................... 156 Fig 8-65 Plastic creep ................ ........ .................................... ........ ... ................. ... ....... ......... ............ 157 Fig 8-66 Stress distribution in plastic formations .................... ... ..................................................... 157 Fig 8-67 Crystalline swelling ...................................... ............. ................................. ....................... 160 Fig 8-68 Osmotic swelling ............... .... ..... ... .................................................................... ....... ... ...... 161 Fig 8-69 Pumping the BHA into packoffs .. ...................................... .... ............ ........................... .. .. . 164 Fig 8-70 Rock strength and drillability ......................................................................................... ... 168 Fig 8-71 Unconsolidated sand ......................................................................... .. ............................... 171 Fig 8-72 Fractured and faulted formations ....................................................................................... 174 Fig 9-1 Differential pressure ................ .. .. .. .................... .. .... .. .......................................................... 179 Fig 9-2 Collapse of the filter cake .. .................... .. .... .... .. .. .. .. .. .. ............... .. ... ... ................................. 181 Fig 9-3 The chain of events leading to differential sticking ............ .. .............................. ................. 182 Fig 9-4 Differential pressure behind the contact area ................................................... .. ... ...... ........ 185 Fig 9-5 Differential pressure and time .......................... ................ ............ .............. .... ..................... 186 Fig 9-6 Effect of filter cake on formation pressure drop .................................. .. .............................. 186 Fig 9-7 Dynamic filter cake .......................................................................................... ....... ........ ..... 188 Fig 9-8 Static filter cake ............ .. ...... ............................................................................................... 188

267 'l (. 11pyright :!rHlI . Drilh~rt Lnginccring Inc.

Fig 9-9 Thick, permeable filter cake ..... ....................................... .. ................................... ..... ........ .. 189 Fig 9-10 Filter cakes and shale .. .... ... .... ....... .. .................. .................... .. .... .... .. ... ..... .... ..................... 190 Fig 9-11 Di fferential pressure wi th lubricants .............................. .. ........ ................................... .. .. .. 192 Fig 9-12 Contact area vs. pipe size ................................................................................................... 194 Fig 9-13 Keyseat contact areas ................................... .... ................. ................. .... ......... ....... ............ 194 Fig 9-14 Proud ledges ............................... .. ............ .. ........ .. ................ ........... ..... ..... .... ... .................. 195 Fig 9-15 The drill string lays on the low side ................................................ .. .... ............................. 195 Fig 9-16 Thick filter cakes and cutting beds .. .... .... ... .......... .. ......... .. ................................ .. .. .. .. ........ 196 Fig 9-17 Differential sticking vs. time .. .. .... .... ...... .......... .. ................................... ........... .... ............. 197 Fig 9-18 Side load ....... .... .... ................................................................................................... .......... 198 Fig 9-19 Friction force ... ..... ... ... .............. ... .... .............................. .. ......... ........ .. ... .... ........ .. .. .. ... ..... .. 199 Fig 9-20 Differential sticking force ......................................................... ... ................... ... .. .............. 199 Fig 9-21 Filter cake adhesion .... ......... ... ..... ..... .... ..... ... ................ .... ... ...... ........................................ 200 Fig 9-22 Differential sticking "signature" ................... ............................. ... ..................................... 203 Fig 9-23 Reducing overbalance and "U-tubing" ............................... .. ............................................. 205 Fig 9-24 Spotting Fluids ..... ................. ....... ........................ ............ ...... .. ........... .......... .................... . 206 Fig 9-25 Placement of spotting fluid ......................... .. ........................ ............................................. 207 Fig 10-1 Dogleg ................................................................................................................................ 211 Fig 10-2 Keyseat ........ .... ........... ..................... .. ......................... ... .. ......... ........ .......... .... .... ... .. .......... 212 Fig 10-3 Factors affecting keyseat formation ................................................................................... 212 Fig 10-4 Side load and doglegs ................................................... .. ........ ........ .............. .. .. ..... ............ 213 Fig 10-5 Horizontal wells ............................................................. ................... ... ...... ................ ..... ... 213 Fig 10-6 Keyseats in ledges .......... ... .... ..... .. ........ ......... .... .. ................ ....... ..... ..... ........ ... ............ ....... 214 Fig 10-7 Cyclical overpull .. ........ ........... ............. ......... ...... ... ................. ... ..................... ................... 214 Fig 10-8 Keyseat trend ............................... ........................ ... ........................................................... 215 Fig 10-9 Free weight below keyseat. ................................................................................................ 215 Fig 10-10 Stiff Assembly .............................. .. ...................... .. .......... .. ..... .. .................. .... ................ 218 Fig 10-11 Measuring dogleg severity .................................................................. .. .. .. .... ....... .. .. ........ 219 Fig 10-12 Micro-doglegs ............................. ..... ... .. .... ................................ ....................................... 221 Fig 10-13 Alternating beds cause doglegs .................... .. .......... .. ..................................................... 221 Fig 10-14 Bit deflection ................................................................................................................... 222 Fig 10-15 Bit walk ........................................................................... ..... ....... .... ........... ... .......... ... ... ... 222 Fig 10-16 Ledges .................................................. ................................. ........................................... 225 Fig 10-17 Faulted formations ....................................................... ........... ......... ... ............................. 225 Fig 10-18 Squeezing salt Fig 10-19 Plasticity of salt .......... ...................................................... 228 Fig 10-20 Graded salt formation ................................................ ........... ............ ... ....... ...... ...... ......... 229 Fig 10-21 Pore pressure in salt fonnations ............................................ ...... .............. ................. ...... 231 Fig 10-22 Under-gauge hole ... .. ... ..... ....... ... .......... .. .................... ...................................................... 233 Fig 11-1 Geolograph chart .. .. ......... ...... .... ........................................... ...... ......... ... ..... ............... ... .... 236 Fig 11-2 Annulus packoffon Geolograph chart ............................................................................... 237 Fig 12-1 Swabbing tight hole ............................................................................ ... ...... ... ...... ....... ...... 241 Fig 12-2 Differential sticking and well control .................. .. ...................... ..... .......... ....... ........ ........ 242 Fig 13-1 BHA model for trips ............... ............................ .. ... ...... ...... .. ...... ... ............................. ...... 247 Fig 13-2 Artificial migration ..... ..... .... ... ............ .......... ..... ... ......... .. .... ..... ... ........ .............................. 249 Fig 13-3 Surging disguised as down drag ............................................................................. ........... 251 Fig 13-4 Pumping the BHA into packoffs ................................................................................ ...... .. 252 Fig 13-5 Weighted slug .................................................. ....................... .... .. ........... ...... ... ................. 253 Fig 8-1 Kirsch equations for well bore stress ................................................................................... 263

268 f l '\'p~nght ~II/) I. f)nlbt:1 t I IlgIl1L'I,;nng Inc.

Index

acid pills ...... ........ ............. .................... .. .. ... 227 adhesion ...... ............ .... .. .. ..... ...... .. ........ .. .. ... 200 aerated muds ............ ....... ... .. .... .... .... .. ........... 94 air drilling ..................................................... 86 angle ofrepose .......... .................................. lll anisotropic stress distribution .... .. .. .... ..... .... 122 annular cuttings concentration ..................... .46 annular velocity .. 34, 43, 44, 45, 62, 63, 68, 69 apparent rock strength ................................ 109 apparent viscosity ... ..... ................................. 52

vs. shear rate ............ .... ......... ... .... ... .......... 52 artificial migration ......................... .. ....... .. .. 249 asymmetrical flow profile ............................. 62 axial strain .. ................................................. I 08 axial stress ................................................... 128 backing off ....... ...... ..... .... .... ..... ... ... ... .. ... .... . 208 ballooning ................................................ .. . 156 barite sag ..................................................... 243 barite slugs ........................................ .......... 253 bed formation

limiting .............. .. ..................... .. ... 63, 76, 81 regions ......... ... ....... ............. ...................... 73

bed height .................. ................................... 68 critical ...... ................. ... .... ... ... ..... .... .......... 70 equilibrium .. .. .... ................ ..... ................... 70 estimating .................................. ... .. ... .. ...... 72 vs. surface volume .................................... 72

bedding planes ...................... .. ... ..... ...... 30, 143 beds ......................................... See cutting beds Bentonite ... .. ... ... ... ... ............. ....... ... ............ . I 07 Bentonite filter cakes ...... .. .. ........... ... .... ...... 196 BHA

model for trips .. .. ...................... .. ....... ..... 247 sti ffness .... ..... ................. .. ........ ................. 32

Bingham plastic ................... .. ....... .. ........ 50, 52 bit

choosing ....... ...... ..... .. ... ....... ...... ................ 32 deflection ......... .................... ................... 222 life, lengthening ..... .. .. ....... .... ..... ............. .. 33 minimum effective diameter ... ... ............. 222 stabilization ............... .. .. ..... ... ... .... .. ..... ...... 33 walk ........... .. ............................................. 30 walk, illustrated ................. ................ ... .. 222 walk, preventing .................. .. ......... .......... 33

blooie line

269

airflow at .. ........ ............ ............................. 85 loss of air volume ..................................... 89 monitoring ....... ......................................... 94

blowouts ... ......... .................................. 202, 241 BOP ....... .............................. ........ .. .. ........... 250 BOP failure ................ ................. ....... ..... .... 202 bottom-hole assembly ... . 77, 99, 220, 221, 224,

226,227, 247 changing .......................... .............. .. ........ 219

bottom-hole pressure79, 80, 81, 85, 87, 88, 92, 93,94, 98, 136,243,246

bottom-up communication ... I I, 12,20,21,22, 25,28

box of crabs mentality .................................. 21 Boycott settling ....................................... 59, 60 Boyle's principle .... ............ ........................... 83 breakout ............................. ......... ... .... ..... .... 155 bridging ........... ...... ... ...................... .... ...... .. ... 37 brittle rocks ................................................. I 14 buoyancy ...... ..... .... .. ... ... .......... ............ .......... 43 capillary action ................................ ... 149, 152 carrying capacity ........................................... 49 case studies

Dynamite Factories ...................... .. ....... .... 17 The Great Train Wreck.. ..................... ...... 15 The Jinxed Semi-Submersible .................. 15

casing costs, minimizing ............................... 32 casing program .................. ... .. ......... ............. 31 cathodic currents ...... ......................... .... .. ... . 208 cation .......................................................... 159 caving ... ... ....... ... ........ ....... ........................... 155 cementation ................... ....... ... .................... 110 centralizers ... ... ........ .. ... ........................... ... . 202 charts, mechanical vs. computerized .......... 238 chemically stressed shale ................. .. ......... 169 Chlorites .............................................. 106, 107 choking velocity ........................................ ... 85 Circulating Stroke Factors ............................ 82 clay, composition of ................................... 106 coiled tubing ................................................. 81 collars ....... ................ .... ........ .... ......... .......... 220 colloidal solids .................................... 1 06, 189 communication

bottom-up .............. I I , 12, 20, 21, 22, 25, 28 issues ........................................ ... ..... ......... 27

(( Ct'\pyriglll 200 I Drilberl rn!cunecring Inc.

lack of.. ............... ..... ........ ......... ........... ..... 11 differential sticking ......... .. ..... ..... .. 38, 179,255 compressibility ...... ... ... .. ..... .. ................. .. ... .. . 83 factors affecting .... ... .... ........................... 196 compressi ve rock strength ..... ....... ...... ..... .. . 108 force ..... .... ....... .. .... ... .... ......... .................. 199 consistency curve ......... ..... .. ... .. ........ .... ......... 50 prevention ............................................... 20 1 creeping fo rmations signature of ............................................. 203

factors affecting ................ ...... ........ .. ...... 230 warning signs .......................................... 203 stuck pipe avoidance .. ... .. .... .... ................ 232 when to expect.. ..... ... ......... ..... ..... .... .... .. . 20 I warning signs ...... .. ................................. . 231 dispersion ............. ..... ....... ... ..... ... .. ... .. .. ... .. .. 107 when to expect ...... ........... .. .. .. ... ... .. .... ... .. 230 doglegs ........ 194, 211, 2 12, 2 16, 2 18, 219, 220

crippling the pumps .... ...... ..... ............ ... ... ... 208 and ledges ............... ........ ........................ 225 critical bed height ....... .. .. ..... ... ... ........ ..... 70, 71 bending stress ... ......... ...... .. ................ ..... 244 crystalline swelling ........ ... .... ..... ..... ..... ..... .. 160 keyseat effect ............. ........ .................... . 21 I cutting beds ............. .... ... ...... ..... ... .... ... 196, 202 limiting severity .. .... ..... ....... ........ .... .... .... 219

causing excessi ve torque .. ..... .............. ..... 81 side load effect on .. ..... ..... ......... .. ........... . 213 continuous moving ........ ..... .... ........ ..... .... . 75 double-angle theory ..... .... ... ....... ........... .. .... 129 critical height .... ........................ .... .. ...... ... . 70 down drag ....... ... .... ......... .. .... ..... ... ............ .. 251 effect of mud on height... .... ....... ... ...... ..... . 63 drill collars, tendency to stick ......... .............. 33 effect of viscosity on ....... .... ..... ..... ... ... .... .. 65 drill string effect on B H pressure ........ ... .... ....... .. .... ... 8 1 failure .............................. ........................ 244 erosion of .. ....... ... ..... ..... ..... ..... ........... .. .... . 69 vibration ......... ........ ... ... .. .... .......... ....... .. .. 153 formation angles ................. .... .... ... ........ .. . 59 drilling mud, fine tuning to the well ............. 34 formation regions ... ...... ............................ . 73 dune transport ... ........... ....................... .......... 75 stationary .... ... ... ... ... ...... .. .... .............. ....... . 7 5 dynamic filter cake ... ............ .......... .... ..... .. . 188 suspension and movement.. ... .. ................. 73 dynamic friction .. .......... ....... .... ...... ... ... .. ... .. 154 transportation, illustrated .......................... 75 eccentricity ... ... ... ... ........ .................... ...... 56, 78 velocity across top of.. ...... ... ...... ............... 64 ECD ................ ... ........ ........... ........................ 80

cutting transport ............... ........ ..... .. ...... .... ... . 74 effective stress, defined ... ........ .. .. ..... .......... 113 cutting velocity .... ................................... ...... 42 elastic strain ..................................... ....... .... I 14 cuttings elastomer seal ... .... .. ...... ..... ......... .. .. ............ 242

concentration, reducing ............................ 63 elongated shear ........................................... 155 initiating rolling .. ...................................... 63 equilibrium bed heigllt... ... .................... .. 68, 70 initiating transport ....................... ....... ....... 57 equipment failure .............. ... ............... ........ 244 lack of ............. ... .... ................................. 23 1 exfoliation ........ .. .... .. .. ... .. ........ ... .... ...... .. ..... 156 maximizing slip velocity .... .... ............. ..... 62 filter cake .... ........ ........ ....... . 180, 187, 192, 20 I migration ............ .......... ........ ..... ... .... .. ... .... 59 adhesion .... .. .... .. ....... .. .... ..... .................... 200 recycling .... ............ ..................... ... ........... 46 check valve effect ................ .......... ... ...... 241 removing .. ... ..... ..... ......... ................... ...... .. 76 effect of pressure on ..... ... ... ... ..... ..... ..... .. 193 settling .. ......... ....... .... .... ............... ............. 54 factors ....... ......... ...... .. ... .......................... 191 surface area ..... .... ....... .. ............ ................. 51 filtrate transport mechanism ...... ...... ....... .... .......... 6l drainage of ... ..... .... .... .... ....... .... ...... .. ....... 202 transport ratio ............................................ 56 effect on stress ........................................ 152 velocity ....... ..... ...... .. ....... .... ...... .. ..... ... ... ... 62 filtrate invasion

cyclic drag ........ .. .... ..... ... .... ..... ......... ......... .. 214 contributors to ....... .. ... ... .... ....... ......... .. .... 149 cyclical overpull .... .......... ........ .... ....... ........ 214 effects of .. .... ....... ........ ..... ........ ..... .......... 148 differential force .. ..... ....... .. ... ............ .......... 184 minimizing .............................................. 150 differential pressure filtration control ..... ...... ..... ...... ...... .............. 165

development of .. ............. .. ............ .... ...... 196 fishing jars ...................... ... ............ ............. 208 effect of time ....... ....... ....... ... ....... ... ..... ... . 197 fishing techniques ............. .... ........ .............. 1 0 I effect of time on ......... ............ ..... ........ ... . 202 flocculation ................................. ................ 20 I

270

flow horseplay ....................................................... 21 index ........................... ... ........................... 64 hydrational stress ................. .................... .. . 143 profile ..................... ........ ... .................. 45,46 hydraulic fracture ......................... .............. . 156 profile, asymmetrical ... ............................. 62 hydrostatic pressure .................................... 253 rate, maintaining adequate .......... ... ....... .... 96 Illites ................................................... 1 06, 107 regime ................................................. 47,62 inclination and direction

fluid choosing .................................................... 29 loss ................... ............ .. ......................... 203 impact on stuck pipe ................................. 29 loss, decreasing ....................................... 192 inclination angle ................................ ........... 58 rheology ........................... ... ..... ............ ... .. 47 inclination regions ........................................ 58 velocity ............................................. 33,243 induced kicks .............................................. 241

foam in-elastic strain ............................................ 1 14 drilling ...................... ................................ 83 inhibition ..................................................... 165 quality ....................................................... 90 in-situ stress ........................................ 118, 138 viscosity .................................................... 91 in-situ stress regime .................................... 139

freeing procedures ............. ......... 100, 170, 204 intergranular stress ...................................... 1 13 for key seats ...................................... ...... 216 jarring ...... ...... .............................................. 227 ledges .......................................... ..... .... ... 227 junk stiff assembly sticking .... ........................ 220 defined .................................................... 175 under-gauge hole ........................ .... ........ 234 freeing procedures .................................. 175

friction .................................... 44, 56, 110, 154 warning signs ................................ .......... 175 friction force .................. ...... ............... 199, 200 when to expect trouble ............................ 175 Geolograph ................................................. 236 Kalonites ............................................. 106, 107 H2S ............................... ....................... 243,250 key lessons ........................................ 12, 18, 26 HeR ............................. See hole cleaning ratio keyseat ................................ 194, 195, 202,212 Hcrit .............................. See critical bed height caused by doglegs ................................... 211 heaving ................................................... ..... 158 contact areas ........................................... 194 Heim's rule ......................................... 122, 143 factors affecting formation of.. ............... 212 helical shear ................................................ 155 free weight below ................................... 215 Herschel Buckley rheological model... ......... 52 freeing procedures .................................. 216 heterogeneous suspension ....................... 6 I ,74 minimizing .............................................. 216 Hindinburg accident .......... .......................... . 11 trend, illustrated ...................................... 215 hole cleaning ................... 34, 41,78,79,80,82 warning signs .......................................... 214

air drilling ................................ .. .... ..... 83,86 when to expect ........................................ 214 anticipating problems ............................... 95 kick deterioration of ......................................... 87 induced ........... .... .................... .... ............. 241 ease of ..... ........ .......... ................ ... ..... ........ 61 kill weight mud ................................ ....... 247 efficiency .................................................. 57 rotating while circulating out... ............... 242 maintaining adequate .......................... 93, 96 slowing pump rates ........ ......................... 246 measuring success of.. .............................. 96 kill sheet. .................. ................ ................... 247 monitoring trends ....... .... .. .. ... .................... 97 Kirsch equations ......................................... 123 observing trends on Geolograph ............... 98 laminar flow ............ .... ............... ...... .48, 50, 62 problems ................................................... 95 illustrated .................................................. 47 ratio ............................ ...... ................... 71, 72 profile ........................................................ 45 warning signs ............................................ 98 ledges .............................. ............ 195, 202, 211

hole size ........ .... ....... ... .... ...... ........................ 32 formation of .............. ..... ... ............ .......... 225 homogeneous suspension ....................... 61 , 74 freeing procedures .... .. ............................ 227 hoop stress ...................... .... ................ 119, 120 keys eats in ........ ........ ........................ ....... 214 horizontal production ................................... . 30 preventing trouble with ........................... 226

271 , Cppynglll 2011). Drilhcrt hlginccring Illl'

warning signs .. ....... .. .. ..... ........................ 226 when to expect .................. ........ .......... .... 226

lithographic chart ... ..................................... 247 lost circulation .................................... 241. 243 low frequency resonance ................ .. .......... 101 low frequency resonance tools ................... 208 lubricant

decreasing fluid loss with .............. .. ....... 192 differential pressure with ........................ 192 effect on adhesion ................................... 200 effectiveness of.. .......................... .. ......... 191 fi lter cake factor. ...... .. ............................. 191

lubrication, depletion of... .................. .. .. .. ... 197 marl ....................... ........................... ........... 228 Marsh funnel viscosity ..................... .. ........... 54 matrix stress .............. .... .............................. 1 13 measurements. taking ................................... 30 mechanically stressed shale ................ .. ...... 167 micro-doglegs .......... ........... ... ................. .... 221

freeing procedures ..................... .. .......... . 224 preventing .... ....... .................................... 224 warning signs .......................................... 223 when to expect ...... .. ................................ 223

migration. artificial ..................................... 249 minimum effective bit diameter ................. 222 misting ......... ....... .................. ............... ......... 89 Mohr's circle .. .. ........................................... 129 Mohr's failure envelope .............................. 131 momentum ....... ......................... .................... 43 morale

barometer ... ............................................... 20 contribution to earned trust.. .. .... ............... 20 defined ...................................................... 19 measuring ........................ ...... .............. ...... 19

MTV (minimum transport velocity) .57, 63,69 mud

and creeping formations .... ........... ... .. ..... 232 bucket. ................... ........... ....... .. .... ... .. ..... 246 effect of salt formations .......................... 229 effect on velocity .......... ... .. ....................... 64 impact of solids on .............. .................... 191 management of ....................................... 249 properties ............ ................... ................... 63 ring ................ ....... ............. ......... ......... 88. 89 velocity ....... .................... .......... ................ 65 weight .... ..... ..... ..... .................................... 77

allowable window ................. 31. 131. 134 contribution to stuck pipe .................. .. . 34 effect on momentum .......................... .. .43

272

effect on slip velocity .......................... .43 impact of.. ........................................... 165 impact on hoop stress ........................ . 127 influence on hole cleaning ................... .43 influence on momentum ...................... .44 Ii ft from buoyancy ............................... .43 raising ........... ...... ..... .......... ... ..... ......... 139

natural bit walk ............................................. 30 Newtonian fluids ........................................... 50 normal fau lting ..... .. .... .. .............. 138, 140, 145 open hole section. selecting .......................... 31 osmotic swelling ........ .. ............................... 161 overbalance

balancing with osmotic pressure ............. 151 contribution to filtrate invasion .............. 149 defined .................................................... 146 filter cake factors .................................... 193 impact on osmotic flow .......................... 1 52 influence on differential sticking .......... .. 184 minimizing .............................................. 201 reduction of... .............. .. .......................... 150

overburden stress ........................................ 1 16 overburden. affect on creep ........................ 230 packoff ........ ...... ........ ..................... ....... 37. 166

spotting .... ................... ..... ..... .................. 243 pattern recognition .............................. 236. 239 penetration rate ....................................... 55.78 percent lifl .............. ......... ................. ..... ........ . 43 permeable formations ................................. 201 personal injury. avoiding ............................ 244 pipe

eccentricity ................................................ 56 resonant vibration .... ............. .. ................ 208 rotation ........ .. ...... .. .. .. .............. 56, 78, 80, 81 static ... ..................................................... 202

pit vo lume. monitoring .. .. ........................... 242 plastic creep .......................... .. ............ 1 55. 157 plastic shale ........................................ ........ . 228 plastic viscosity ......... 48, 51. 54.169. See also

viscosity plug flow

illustrated .............. ............. .......... ..... ........ 47 inhibiting .... ... ........... ................................. 53

Poisson's ratio .. .. ........ .... ..................... 1 08. 115 pore pressure ....................................... 1 13, 146 positioning the rig ......................................... 29 power law .................................................... . 50 principle stresses ......................................... I 16 problem solving

process ... ........... ....... .................. ............... 24 shear stress ...................................... 50, 76, 112 scientific approach ... ................................. 23 shear thinning ......................................... 53,67 scientific process ...................................... . 24 side load ...................................... 199, 203, 212

proud ledges ................................................ 195 contribution to differential sticking ........ 198 PV .................................... See plastic viscosity side loads .................................. ............ .. .. .. 213 PWD ....................................................... 79, 80 slide drilling .................................................. 81 radial strain .................................... .... ......... 108 slip velocity .............. .42, 44, 55, 57, 58, 62, 66 radial stress ................................................. 127 sloughing .................................................... 158 reckless risk taking ................................. 11, 13 slugging .. ...................................................... 89 reverse faulting ........................... 138, 142, 145 Smectites ............................................. I 06, 107 rheology ........................................... ... ......... . 76 Sodium Montmorillonite ............................ 107 rig positioning ............................................... 29 solids .. 55, 67, 88, 98, 106,112,115,116,150, risk taking ............................................... 11, 13 165,169,180,187,188,189,190,191 rock mechanics ............. ....... ....................... 108 control ....................................................... 35 rock strength ....................................... I 10, 135 impact on mud ........................................ 191 safety valve ... .............................................. 250 surface area of.. ....................................... I92 salt formation ...................................... 226, 228 sonic flow .................... ..... ..... ....................... 87

affect of overburden .... ................ ............ 230 spalling ........................................................ 158 freeing procedures .................................. 232 spotting ............................................... 206, 207 illustrated ................................................ 229 squeezing formations .......................... 211, 228 impact of purity ...................................... 230 stability pore pressure .. ......................................... 23I affect ofrock strength on ........................ 135

saJtation ... .. ................ .................................... 74 affect of stress on .................................... 139 sand cI usters ..... ............... ........ .................... .. 74 affect of temperature on .......................... 136 scientific approach to problem solving ......... 23 effect of filtrate on .................................. 148 settling velocity .......... ..................... ............ .. 65 factors affecting ...................................... 132 shale stable foam ........ .. ................. ......................... 90

affect of clay upon .................................. 108 standing waves ..................................... ...... . 227 chemically stressed ............... .. ................ 169 static formation of ............................................ 105 filter cake ................................................ 188 heaving .................................................... 158 friction .................................................... 154 mechanically stressed ............................. 167 pipe ......................................................... 202 permeability ............................................ 106 stiff assembly .............................................. 218 plastic creep ............................ .. ........ ...... 155 freeing procedures .................................. 220 porosi ty ................................................... 106 sticking ................................ ... ................. 218 reducing permeability of... ...................... 151 sticking warning signs ............................ 219 sloughing ................................................ 158 stiff foam ................ ..... ........................ .......... 94 spalling .................................................... 158 strain, defined ............................................. 114 stress-induced failure .............................. 155 stress warnmg SignS anisotropy ...... ......................... 125, 138, 139

chemically stressed ........ ..................... 169 around well bore ..................................... 119 mechanically stressed ......................... 167 axial .............. .. ........ ............... ................. 128

when to expect instability .............. ......... 163 components of.. ....................................... I 17 shear failure contours .................................................. 124

caving .......... ... ..... ....... ... .......................... 155 defined .................... ................................ 1 12 elongated shear ....................................... 155 determining size of ................................. 117 helical shear ........ .. .................................. 155 hoop ................................................ I 19, 120 toric shear ............................................... 155 in-situ ...................................................... 118

shear rate ... .............................................. 50, 67 overburden .............................................. I 16

273 l L ('flY' Igln ~I)() I. J)nJh~n [ ngilH.'ning Inc.

principle ................... ..... ........ ... ..... ..... ... .. 11 6 under-gauge hole .... ........ .. .... ...................... 2 11 radial .. .. ... ..... ... ... .... ..... ...... .......... .. ...... .. .. 127 causes of ...... ........... ........ ... .. ... .. ....... ....... 233 streamlines .. ........ .. .. .... ... ................... ...... 123 free procedures .................... ...... ...... .... ... 234 tri-axial ... ..... ... .. ........ .. .... .......... .... .. . 11 6, 128 stuck pipe prevention .... .. ...... ....... ...... .. ... 234

strike slip faulting ... ... ......... .. ...... 138, 141 , 145 warning signs ... .. ... ........ ...... .. ... .. ... ...... .... 233 stuck pipe when to expect.. .. .. .. ................................ 23 3

bridging .. .. ..... ..... ....... ... ..... ..... .. ......... ... ..... 37 unscheduled events categories o f. .. ..... ..... ..... ... .. ...... ... .... ... ... ... . 37 cost of ...... .. .......... .. .. .. .. .. .. .. .. ..................... 11 defined ...... ... .... .......... .... .. ... .. .. ...... ...... ... ... 37 events leading to ........ ..... .... .......... .. .... ...... 11 mechanisms ... ....... ........ ........ .... .. .. .... ... .... . 37 U-tubing ... .... ... ...... ...... ... ........ ...... .... .......... . 205 micro-doglegs ... .. ... ... ....... ... .. .... ...... ..... .. . 224 Van der Waals ............................ .............. ... . 76 pack-off. ... .......... .... .... .. .. ... ................. ... .... 37 velocity

surface area of cuttings ..... ..... ..... .... ... ... ........ 5 1 annular .... .. ...... 34, 43, 44, 45,62,63,68,69 surging .. ..... .. .. .... ... .... ..... ..... ... .... . 243, 251 , 254 cutting .... ........ ... ... ..... .... .... ..... .......... ......... 42 swabbing .... .. ... ... .. ..... .... ...... ... ... .... .... ... ...... . 254 cuttings ... ....... ........ ..... ..... ........ ... .... ... ........ 62 target dependence on flow rate .. ...... .. .. ............... 68

choosing too many ... ... ........... ... ... ...... .... ... 28 disturbing ........ ...... ... .. .... .. ........ .. ....... ........ 65 natural path to .......... ... ......... ..... ...... .. ........ 29 effect of mud on ...... .. ........................ .. .. .... 64

technical limits training ..... ..... ... .. .... ... ... ...... . 28 effect on bed height ........................... .. .... . 69 tectonic forces ..... ........ ....... ..... .... .... .. .. ...... .. 11 6 effect on cutting beds .............. .. ........ .. .. .... 68 temperature ......... ... ... ....... ........ ... 136, 193, 230 flow profile .... .. ........ .. .. .. .... .. ........ ............ .45 tensile failure .... ....... .. ....... ..... ... ........... .. ..... 156 fluid .. ....... ... .. ... .. ... ... ..... ... ..... ..... ........ 33,243 threshold RPM ........ ....... ... ...... ...... ................ 79 initiating cuttings rolling .......... .. ........ .. .... 63 threshold velocity ... ...... ............ ... .... ..... ... .... . 68 m~ .... ........... ..... ...... .. .... ... ... .. ... ........ ........ 65 tight hole .. .... .. ....... ...... ... .... ... ..... ........... .... .. 241 proftle .. .. ... ... .... ........... ... ... ...... ....... ............ 67 time .. ........... ... ....... .. ...... .. .... .... 56, 82, 197, 202 profiles in horizontal well .... ..................... 64 tori c shear ..... .. ... ... ...... ... .. ... ... ... ... .... ... .. ... ... 155 settling ........... ...... ... .. ... ... .. .. ..... ... ..... ......... 65 torque ........... ... .......... .......... ........ ........... .... .. . 77 slip .... .. .... .. .... .. 42, 43, 44, 55, 57, 58, 62, 66 transport ratio ..... ... ...... ....... .. .42, 43, 56, 57, 65 threshold ................. ............. ...... ... .. .......... 68 transport velocity, minimum ........ ...... ........... 57 vibration trend analysis ..................... ............ .. ........ ... 239 dampening ....... ................ .. ... .............. ..... . 32 trends .. ..... .. .. .... ..... .... .... ..... .... ... .. ..... ... ... ...... 235 drill string ........ .. ...... ........ .. .. .. .... ............. 153 tri-ax ial stress ........... .. ........ ................. I 16, 128 viscosity .. ............ 50. See also plastic viscosity trip sheets .................. .. ...... .. .......... .. .... 246, 248 apparent ... ... .... .. ..... ........... ....... ...... ... ..... .. . 52 trip tanks .... ... .. ..... .......... ... .......... ...... ... .. ... .. 248 Marsh funnel .. .. ...... .... .. ........ .. .. .. .. ... .......... 54 tripping ..... .......... .. ....... .... .... ... .. ...... ...... ...... . 186 reduction of.. .. ... ... ..... ...... ..... ... ................. . 55

circulating after ... .. ... ..... ... .. .. ...... ... ... ...... . 255 volumetric cuttings concentration .. ...... ...... .. 42 drills .... .. .. ...... ... ...... .. .... .. ... .... .. .. ........ ...... 251 wall contact.. ............ .... .. ............ . 193, 194, 202 planning for.. ..... ... ... .. ..... ........ ....... .. ..... ... 245 filter cake effect .. ........ ........ .. .............. .... 196 preparatory steps .. .... .. ... .. .. ... ... ... ... .. ... ... .. 246 washout ........ ... ........ .. ....... .. ... .. ... ..... ........ 33, 34

TRUE train ing ................................. .. .... ...... . 27 water turbulent flow ................ .. ................. 34, 48, 62 activity .. .... .... .. ....... ...... ............. ..... ...... ... 149

illustrated ............ ... ... ..... .. ... ..... ... .. .. .. ... .. .. . 47 osmotic flow of.. ............. ........ ................ 151 unconsolidated fonnations .... ...... .. .............. 17 1 well bore unconsolidated sands failure of .... .. .... .. .... .... .. ............... .. .. .. .... .. 130

freeing procedures ...................... .... .. .. .... 173 geometry ...... .. ............... .. ... .... ........... 38,2 11 ill ustrated .................................. .. ............ 17 1 instability .... .. .. .. .. .......... .................. 171,254 waming signs .... .... .. .. ............ ........ .. .... .... 173 stabi lity .... ... .. ...... ... ..... ... .. ... .......... ... ......... 30

under-balance, freeing stuck pipe with ...... . 242 well control ......... ..... ... ... .. ... .. ... .. ................ . 248

274 (

well path trajectory ... ...... ....... ... ..... ........ ....... 28 well planning

reason for ....... .... .... ........ .. ............ ....... ...... 27

wire line resonance tools ............................ 224 yield point... .. ............ .... ....... .48, 50, 53, 54,64 Yield Power Law .... .. ... .. ..... ..................... .. ... 52

well path trajectory ... .... ...... ....... .. ........ .. ... 28 wiper trips .. ..... ........ ......... ... ..... ..... 81, 166,254

YP ... ....... ...... .................... ........ See Yield Point Zeppelin accident... ... .. ... ........... ... ...... ... .... .... 11

wire line ... ....... ...... ........ .. .. .... ............ .. ........ 194

275

Notes

276 "( Cnp~llght ~OU I Drilhat 1.JlgII1~lring In!.:.

Useful Conversion Factors

Pressure I Ib/in2 = 2.0360 inches of Mercury I atmosphere = 14.70 Ib/in2

Length I foot = 0.3408 meters I inch = 2.540 centimeters

Weight I pound = 0.4536 kilograms I kilogram = 2.2046 pounds

Volume I barrel = 42 gallons 1 barrel = 5.61456 ft3 1 ft3 = 0.1781 Bbls I ft3 = 7.4805 gallons I gallon = 0.1337 ft3 I gallon = 231.000 in3 I gallon = 0.8327 imperial gallons

Density 1 cubic foot of water = 62.316 Ibs 1 gallon of steel = 65.5 Ibs 1 gallon of barite = 35 Ibs 1 cubic foot of cement = 96 Ibs

I atmosphere = 1.013 x 105 N/m2

I meter = 3.2808 feet I meter = 39.37 inches

I pound = 4.448 Newtons I metric ton = 2,205 pounds

1 liter = 1,000 centimeters3

1 liter = 0.2642 gallons 1 liter = 0.0353 ft3 1 ft3 = 28.317 liters 1 ft3 = 0.02832 meters3 1 gallon = 3.785 liters

1 gallon of water = 8.3304 lbs 1 barrel of steel = 2750lbs 1 cubic foot of barite = 261.8 Ibs

Volume Equations

Hole Volume in Bbls/ft = 1029.4

Annular Volume in Bbls/ft =

Where D is in inches

Steel displacement in Bbls = Hook load 2,750lbslBbi

Bottoms up strokes = Annular volume (Bbls) Barrels per Stroke

Where D is the large diameter in inches and d is the small diameter in inches