By S. J. Kravits, A. Sainato, and G. L. Finfinger 

UNITED STATES DEPARTMENT OF THE INTERIOR C 

MINES 75TH AN* 
UNITED STATES DEPARTMENT OF THE INTERIOR 

Donald Paul Hodel, Secretary 

BUREAU OF MINES 

Robert C. Horton, Director 
Kravits, S. J. (Stephen J.) 

Chnparison of rotary and in-liole motor techniques for drilling horizontal horctiolc~ in cual. 

(lieport of inrcstigations : 8933) 

Iii hl iography : p. 19. 

Supt. of 1)oc.s. no.: 1 28.23:8933. 

1. (.oalhed methane iir;linagc-Pennsylvania. 7. Iloring. 3. Vine 

ventil:ltion. I. Sainato, Allwrt. 11. Finfinger, (icrald 1.. 111. 'fitle. 

I\'. Series: Ilcport of investigations (Cnitcd Statcs. Ilureau of klincs) ; 

8933. 

TN23.[!43 rl'N.7051 622s 1622'..12] 84-23099 
CONTENTS 

Page 

Abstract .............ee..........e.e.e.....ee...e....e..........ee.ee.......... 1 

Introduction .......e...e.........e....e.............e....e...eee..eee.........e 2 

Acknowledgments ................................................................ 2 

Test site ........................e....eee.......................e...e.......... 2 

Rotary borehole drilling ...........e..........e..ee..e.........e.e............. 3 

Equipment and procedures ..................................................... 3 

Borehole surveying .................e......e....e..ee.....e....e...e.e.e...... 6 

In-hole motor borehole drilling ...........e...eee.e.e.e.................e...... 8 

In-hole motor description .................................................... 8 

Deflection shoe description .................................................. 9 

Borehole surveying ........................e........e......ee.eee....e......e. 11 

Establishing deflection rates ....................e.e........e.............e.. 12 

One- and two-step bit projections ............................................ 13 

Drilling paramete, rs and penetration rates .................................... 14 

Sidetracking ..........e..........e.e..e..........a.e......ee..........e...e.. 15 

Timestudy comparison ........................................................... 15 

Drilling cost comparison ...........e..e...........e........e................e.. 16 

Conclusions ........e........e..eee...ae.e....e...e...ee.....e.....e.........e.. 16 

References ................e.....................e.e.ee..............e.......... 19 

Appendix A*-- Surveying procedures .............................................. 20 

Appendix B.-- Deflection rate components and bit projections .................... 25 

Appendix C.--Timestudies of each borehole ...................................... 30 

ILLUSTRATIONS 

Mine map ................................................................. 3 

Longyear drill .......................................................... 4 

Power unit ............................................................... 5 

Various rotary drill string configurations ............................... 6 

Borehole plots showing vertical deviation ................................ 7 

Survey instrument ........................................................ 8 

Plan view of boreholes ................................................... 8 

Navi-Drill in-hole motor ................................................. 9 

Deflection shoe .......................................................... 10 

Deflection shoe side force .............................ee.eee............ 11 

Various tool face settings and their effects on borehole trajectory ...... 12 

Drilling parameters of in-hole motor ..................................... 14 

Available drilling time .................................................. 16 

Reading film disks ....................................................... 20 

Survey hardware .......................................................... 21 

NL Sperry-Sun protective case. survey instrument. and snubber ............ 21 

Orienting sub ............................................................ 22 

Alignment of snubber. mule shoe. orienting sub. and deflection shoe ...... 22 

Lead tattletale before and a£ ter completing a borehole survey ............ 23 

Tool face setting guide .................................................. 24 

Sidetracking with an in-hole motor ....................................... 28 
TABLES 

Page 

Performance of various rotary drill strings.............................. 6 

Bevel springs used with deflection shoe.................................. 9 

Calculated deflection rates.............................................. 13 

Timestudy comparison of the two drilling methods......................... 15 

Initial drilling equipment costs, both rotary and in-hole motor.......... 17 

Rotary and in-hole motor drilling equipment costs........................ 18 

Cost comparison of the two drilling methods.............................. 18 

Calculating deflection rate components................................ 25 

Rotary drilling timestudy.....................................~~.~~.. 30 

In-hole motor drilling timestudy......................................... 31 

UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 

f t foot lb pound 

ft-lbf foot pound (force) min minute 

ft/min foot per minute mo month 

gal gallon Pet percent 

gal/min gallon per minute psig pound per square inch, gauge 

h hour r/min revolution per minute 

hp horsepower V volt 

in inch Yr year 
COMPARISON OF ROTARY AND IN-HOLE MOTOR TECHNIQUES 

FOR DRILLING HORIZONTAL BOREHOLES IN COAL 

By S. J. Kravits,' A. sainator2 and G. L. ~infinc~er~ 

ABSTRACT 

This Bureau of Mines report describes and compares the procedures, 

capital investments, and operating costs of rotary and in-hole motor 

drilling techniques used to drain methane gas from the Pittsburgh Coalbed in an underground mine located in southwestern Pennsylvania. A 

timestudy was conducted during the drilling of each of two boreholes, 

and the data were collated to serve as a base for comparing drilling 

procedures and operating costs. 

Findings indicate that drilling with an in-hole motor offers four advantages over rotary drilling; namely, an increase in drilling productivity, fewer worker-hours required, ease of maintaining vertical and 

horizontal bit trajectory, and less expensive drilling cost per foot of 

borehole. 

'Mining engineer. 

2~ining engineering technician. 

3~upervisory geologist. 

Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA. 
INTRODUCTION 

Methane control by drainage is generally accepted within the coal mining industry'as a means of reducing excessive gas 

emissions into the mine environment (1- - 2, pp. 14-16)~~ The Bureau of Mines has 

demonstrated that methane drainage by 

horizontal boreholes is a safe and effective method of removing methane in advance of mining and of controlling methane emissions during mining (1-4). -- Implementation of this technology has 

consistently lowered emissions at active 

faces by at least 50 pct. Although the 

Bureau has rotary-drilled horizontal 

boreholes to depths greater than 2,500 

ft, the technique has not been universally accepted. The major deterrents to 

rotary drilling have been the difficulty 

in maintaining vertical bit trajectory 

within the coalbed and the lack of control in the horizontal plane. Vertical 

bit trajectory is maintained by varying 

combinations of bit rotation, thrust, and 

placement of centralizers on the drill 

string. Strategic placement of centralizers on the drill string results in a 

force being applied vertically on the 

drill bit, which determines the direction the drill bit will cut. However, 

excessive losses in drilling time can 

result from changing the drill string 

configuration each time a certain configuration has been found to be ineffective in maintaining trajectory within the 

coalbed. Until the driller determines 

through trial and error which configuration is most effective, losses in drilling time will occur. 

Within the last 5 yr, experience has 

increased in using in-hole motors to 

drill horizontal boreholes. In 1979, the 

Bureau used Smith International's Dyna- 

 rill^ (in-hole motor) to drill three 

horizontal boreholes in the Pittsburgh 

Coalbed from a directional surface 

borehole (2j. Vertical and horizontal 

drill bit trajectory was maintained with 

relative ease compared with trajectories 

of previous in-mine, rotary-drilled horizontal boreholes . 

This report describes and compares the 

techniques of rotary and in-hole motor 

drilling, the timestudy data, and the 

equipment and operating costs for the two 

horizontal boreholes. Detailed in-hole 

motor drilling information is provided in 

appendixes A and B. 

ACKNOWLEDGMENTS 

The cooperation and technical assist- Bros. Drilling Co., and of Glen Stewart, 

ance of mine personnel, of Maynard Sten- district supervisor, NL Sperry-Sun, are 

berg, technical manager, and Lars Edling, greatly appreciated. 

directional drilling specialist, Boyles 

TEST SITE 

The test site was an 11-entry section 

of an underground mine in the Pittsburgh 

Coalbed in southwestern Pennsylvania 

(fig. 1). Mining of the section was 

abandoned 12 yr ago because of excessive 

gas and water problems that severely hindered coal production. Two horizontal 

boreholes were drilled from the outside 

entries of the section in a direction 

parallel to the future development. 

These boreholes outlined the advancing 

section for more than 1,200 it, shielding 

it from methane emissions. Polyethylene 

pipeline was used to transport methane 

safely from the boreholes to the vertical 

borehole during the drilling and drainage 

phase by using the appropriate gas handling equipment (4). - 

4~nderlined numbers in parentheses re- 5~ef erence to specific equipment does 

fer to items in the list of references not imply endorsement by the Bureau of 

preceding the appendixes. Mines. 
FIGURE 1. - Mine map. 

ROTARY BOREHOLE DRILLING 

EQUIPMENT AND PROCEDURES 

Drill bit thrust and rotation were supplied by a Longyear hydraulically operated drill (fig. 2). The power unit for 

the drill was located 100 ft outby in a 

fresh air entry and was equipped with a 

30-hp, 440-Vac motor (fig. 3). 

The primary objective during rotary 

drilling is to maintain bit trajectory 

within the coalbed by keeping bit inclination to within 1' of coalbed dip. Four 

rotary drill string configurations were 

used to drill the first horizontal borehole (fig. 4). The performance of the 

four rotary configurations and drilling 

parameters used, including their effects 

on bit trajectory, are summarized in 

table 1. Initially, the standard drill 

string configuration (fig. 4A) was used, 

but it was found to be ineffective in 

maintaining bit inclination. Consequently, three other rotary drill string configurations were used to complete the 

borehole. 

The drill string that proved to be the 

most effective in maintaining vertical 

borehole trajectory was the modified 

drill string shown in figure 4B. This 

configuration uses only the front centralizer and the drill collar. Removing 

the rear centralizer tilts the configuration 0.1' upward in the borehole, relieving the weight of the drill collar from 

the blades of the drag bit. Drilling 

with the modified configuration caused 

inclination to build slightly, at about 

1' per 100 ft, eventually resulting in 
FIGURE 2. - Longyear drill. 
FIGURE 3. - Power unit. 
A ,,,,, lO.in cen~rolizers, 3 / ~n 

, DrI casing, 2 q6-n0~ 'Ii BI~, 3'/..-1n OD, , 14-fl collar, 2%-in OD 

pypg

shot survey instrument was used to determine borehole inclination during rotary 

drilling (fig. 6). To determine the inclination of the bit, the timer of the 

survey instrument is set and the instru

ment is loaded with a film disk. The 

loaded survey instrument is placed in 

its protective casing, which is then inserted inside the drill rod and pumped, 

using water, to the end of the borehole. 

At the preset time, the film disk is 

c ,,,,Io-ln cenl~ol~zer, 3T6 I" OD exposed, after which the instrument is 

(Dr~ll cosing, 23(6 inOD 14-fl collar, z34 In OD "t,3'/i1n0? retrieved by a wire line attached to 

the protective casing. Subsequently, the 

film disk is removed, developed, and 

No1 fa scale read (6) - . 

D 

,D~~,I casing, 236-ln~~ 10-10 centr As previously mentioned, there is no 

horizontal control on borehole trajectory 

during rotary drilling; therefore, the 

borehole was surveyed for bearing af

ter borehole completion (fig. 7); The FIGURE 4. - Various rotary drill string config- borehole arced in the right-hand or 

urations: A, Standard longhole; B, modified; Cr clockwise direction, as have the majority 

reaming; D, maximum build. of previously rotary-drilled boreholes. 
A HOR

0 100 200 300 400 SW 6

I I I I I 

BOREHOLE 1 

o rm ern 1.557 fl 

Lb 

kde. I, PLAN VlEW 

Bm 1 

1 1.242" A. 

I ,23MAINS 

. , Prnjrrrd mlb* 

rm 1.557 fl 

b 

kde. I, PLAN VlEW 

FIGURE 5. - Borehole plots showing vertical deviation. 
23 MAINS c 

0 - 2 00 400 

Scale, ft 

LEGEND 

-0- Elevation station 

FIGURE 7. - Plan view of boreholes. 
,Orienting sub 

- Lower bearing housing 

I - 

FIGURE 8. - Nuvi-Drill in-hole rr~otur, 2-3/4-in OD. 

at flow rates of 40 to 70 gal/min and 

pressures of 100 to 650 psig, the helical 

steel rotor rotates inside the rubbermolded stator. Rotation of the drive 

shaft, positioned within the upper and 

lower bearing assemblies, is transmitted 

by the universal joint, converting the 

eccentric rotary motion of the rotor to 

concentric motion. The drive sub is connected to the drive shaft and is the only 

rotating external component of the inhole motor. Both horizontal and vertical 

borehole trajectories can be maintained 

when in-hole motors are used. 

DEFLECTION SHOE DESCRIPTION 

A deflection shoe developed by Conoco 

(8) and Christensen Diamin Products (7) 

was used to maintain desired borehole dTrection (fig. 9). Other control devices, 

such as bent housings positioned over the 

universal joint, are also applicable for 

maintaining borehole trajectory (5). - The 

deflection shoe is a positive, unidirectional, constant-wall-contact device 

positioned on the lower bearing housing 

(fig. 9C). While drilling, there is continuous contact between the deflection 

side of the shoe and the wall of the 

borehole. Bevel springs in the deflection side of the shoe push the shoe away 

from the lower bearing housing. The 

known side force exerted by the springs 

against the wall of the borehole can be 

adjusted by varying the number of springs 

used (between 11 and 14) and/or by using 

springs of varying stiffness (table 2). 

Because coal is a relatively soft material, minimum deflection rates were desired, and therefore, lightweight springs 

were used. The resultant reaction of the 

side force exerted on the wall of the 

borehole is a force exerted on the bit 

180" away from the deflection side of the 

shoe (fig. 10). The direction of the 

force exerted on the bit is called tool 

face direction or borehole direction. 

Tool face direction can be positioned to 

drill up, down, left, or right by manually turning the drill string clockwise 

with a pipe wrench. The driller must at 

all times be aware of tool face direction to achieve desired horizontal and 

TABLE 2. - Bevel springs used with deflection shoe 

to exert side force 

Spring type 

or weight 

Light weight..... 

Medium weight.... 

Heavy weight..... 

Load per 

spring, lb 

49 

64 

7 6 

Deflection 

per spring, in 

0.0069 

.0078 

.0073 

Stress to flatten, 

lo3 psi 

133 

138 

136 
FIGURE 9. - Deflection shoe. A, Description; H; exploded view; C, shoe positioned on 

lower bearing housing of in-hole motor. 
in vertical drop of hole 

trajectory 

FIGURE 10. - Deflection shoe side force. 

vertical borehole trajectory. Various 

tool face settings and their effects on 

borehole trajectory are shown in figure 

11. 

BOREHOLE SURVEYING 

The NL Sperry-Sun magnetic directional 

single-shot survey instrument was used to 

determine inclination, bearing, and tool 

face direction during drilling with the 

in-hole motor. A detailed explanation of 

the procedures for reading Sperry-Sun directional film disks (9) and aligning the 

survey hardware, orienting sub, and deflection shoe is given in appendix A. 

Fifty feet of stainless steel drill rod 

(five 10-ft joints) was used directly 

behind the in-hole motor to prevent magnetic interference of the survey directional compass. The surveys were taken 

30 ft behind the deflection shoe, with 

the survey instrument placed within the 

second and third stainless steel rods behind the in-hole motor. 

The procedure for completing a survey 

while drilling with an in-hole motor is 

given in appendix A. After a survey was 

completed, the inclination, bearing (after correcting for magnetic declination), 

and distance from the previous survey 
FIGURE 11.  Various tool face settings and their effects on borehole traiectory. 

were entered into a "radius of curvature" 

calculator program adapted for a HewlettPackard 34C calculator (calculator program and results available upon request). 

New vertical and horizontal borehole survey locations were determined and plotted 

on section and plan view plots. Before a 

new tool face direction was set (appendix 

A), the actual bit location (30 ft ahead 

of the survey location) was projected. 

Projecting bit position was a process 

that depended on a knowledge of the established deflection rates and one- and 

two-step bit projection techniques. 

ESTABLISHING DEFLECTION RATES 

The deflection rate is the rate at 

which borehole direction (azimuth) and/ 

or inclination will deflect or change 

while drilling. Ideally, the vertical 

and horizontal deflection rate components 

corresponding to tool face settings 

should be determined by field measurements collected during drilling. Because 

only one borehole was to be drilled using the in-hole motor, the average deflection rate magnitude, 0.10" per foot, 

was determined during the first 300 ft of 

drilling. The deflection rate magnitude 

applies directly to tool face settings of 

0°, 180°, and 90" right and left. For 

these four settings there is either a 

vertical or a horizontal component, but 

not both. With all other tool face settings, there are changes during drilling in both inclination and azimuth, as 

shown in table 3. A rule-of-thumb method 

explained in appendix B was used to break 

down the deflection rate magnitude into 

vertical and horizontal components, in 

order to have the capability of accurately projecting the bit position from the 

survey depth. 
TABLE 3. - Calculated deflection rates (using 0.10" per foot 

as deflection rate magnitude) 

Tool face setting 

(right or left) 

lost or dropped angle slightly because of the effects of gravity and because coal is 

a soft material. 

I degree per foot 

NOTE.--These deflection rates are not necessarily applicable to other coalbeds or 

Horizontal component: 

Turn, hole direction, 

even to other coal mines operating in the Pittsburgh Coalbed. Also, these rates were 

Vertical component -- Build vertical angle, 1 Drop vertical angle, 

degree per foot 

experienced using a deflection shoe, a 3-112-in-OD tricone roller bit, and BQ size 

(2-3116-in-OD) wire line drill rod. Usage of other assemblies might result in difdegree per foot 

QUADRANT 1 OR 2 (FIG. 11) 

ferent deflection rates. 

oO............. 

lo0............. 

20°............. 

30°............. 

40°............. 

50°............. 

60°............. 

70°............. 

80°............. 

9001............ 

ONE- AND TWO-STEP BIT PROJECTIONS 

During a one-step vertical projection, 

the deflection rate vertical component 

was used to calculate the projected 

change in inclination from survey to bit 

depth and to project the vertical position of the bit. During a one-step horizontal projection, the horizontal component was used to project the coordinates 

of the bit (appendix B). Borehole trajectory in the vertical plane was of primary importance; therefore, only a few 

one-step horizontal projections were 

made. Examples of one-step vertical bit 

projections are provided in appendix B 

0.000 

.010 

.022 

.033 

.044 

.056 

.067 

.078 

.089 

.lo0 

and plotted on figure 5B. Although onestep vertical projections increased trajectory control, they did not provide the 

necessary information on bit position for 

the end of the next drilling interval. 

Consequently, two types of two-step vertical projections were implemented in the 

drilling plan. 

QUADRANT 3 OR 4 (FIG. 11) 

Type A two-step vertical projections 

were used when the next drilling interval 

applied the same tool face setting as 

that used in the previous interval, and 

therefore, these were essentially one0.100 

.089 

.078 

.067 

.056 

.045 

.033 

.022 

.010 

.OOO 

loo0............. 

llOO............. 

120°............. 

130°............. 

140°............. 

145"............. 

150°............. 

160". ............ 17 0" ............. 180°............. 

step projections extended from the current survey depth to the end of the next 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

yap Not applicable. 

At 90" right or left, the in-hole motor did not hold vertical angle but instead 

0.089 

.078 

.067 

.056 

.044 

.039 

.033 

.022 

.010 

.OOO 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

0.010 

.022 

.033 

.044 

.056 

.06 1 

.067 

.078 

.089 

.lo0 
planned interval. Type B two-step vertical projections were used when drilling 

proceeded with a changed tool face setting. First, the standard one-step ver- 1,000 

tical projection from the survey to the 

current bit depth was calculated. Then, 

using the projected inclination for the 

current bit depth and the deflection rate 

vertical component of the new tool face 

setting assigned to the next drilling 

interval, the vertical bit position for 

the end of the next interval was calculated. Exampales of both types of twostep vertical bit projections are included in appendix B. 

Of the 36 one-step vertical projections made, 29 were within 0.30 ft of the 

plotted borehole trajectory, and 20 of 

the 30 two-step projections were within 

0.50 f t. Although two-step projections 

were not as accurate as one-step projections, they served as useful tools in 30 1 

providing future bit position, resulting 

in increased drilling productivity. Fifteen shifts of the last 22 were productive (60 ft or more drilled) after implementing two-step projections. By comparison, only 6 of the first 17 drilling 

shifts were productive using only onestep projections. 

DRILLING PARAMETERS AND 

PENETRATION RATES 

MOTOR SPEED, r/min 

The second borehole was drilled using 

BQ (2-3116-in OD) size wire line drili 

rod with thrust levels ranging from 2,000 

to 6,000 lb and bit rotation speeds of 120- 

690 to 770 r/min. When tool face direction was changed by more than 90°, thrust + 100- 

levels increased to as much as 6,000 lb 0 

t 

in coal, which was probably caused by the - 80- 

bending of the BQ rod immediately behind d 3 

the in-hole motor. Bit thrust was pro- 0 (r 60- 

vided by the Longyear hydraulic drill, o Iwhile the bit was driven by water forced - 

under pressure supplied by two triple 

piston pumps. The pumps supplied water - 

from a 250-gal holding tank to the inhole motor at 60 to 65 gallmin, which 0 100 200 300 400 500 600 700 rotated the bit at speeds of 690 to 770 PRESSURE DROP, psig rlmin (fig. 12). At 690 to 770 rlmin, 

the motor could generate approximately 20 FIGURE 12. - Drilling parameters of in-hole 

hp. Water pressure to the in-hole motor mot or. 
was maintained between 500 and 700 psig, 

providing a bit torque between 95 and 

135 ftelbf. These parameters were used 

throughout borehole completion. Drill 

borehole effluent (water and cuttings in 

suspension) were discharged into a large 

sump and removed by a low-pressure, highvolume discharge pump into a discharge 

pipeline. 

Drilling penetration rates in coal 

ranged from 0.3 to 1.0 ft/min, averaging 

approximately 0.7 ft/min. Penetration 

rates would decrease at the start of 

drilling with a new tool face setting. 

Lower penetration rates of 0.3 to 0.4 ft/ 

min were especially noticeable during 

drilling intervals of 10 to 30 ft immediately after the tool face setting had 

been changed by more than 90". However, 

an average penetration rate of 0.7 ft/ 

min (10 ft per 14 min) was more than 

satisfactory since the objective of this 

study was not to maximize penetration 

rate per drill rod but rather to maximize the total footage drilled per shift 

through the elimination of trajectory 

control problems. 

SIDETRACKING 

It was possible to sidetrack or start a 

new borehole below the present one while 

drilling with an in-hole motor. Five 

sidetracks were completed, at measured 

depths of 241, 421, 821, 1,187, and 1,427 

ft, to return the borehole back into the 

coalbed after the roof or floor strata 

had been intercepted (fig. 5B). The procedure of sidetracking with an in-hole 

motor and an example projecting the effects of sidetracking are included as a 

section in appendix B. 

TIME STUDY COMPARISON 

A timestudy of rotary and in-hole motor 

drilling (provided in appendix C) showed 

that 49 pct of the total time to complete 

each borehole was occupied by downtime 

and traveling portal to portal. Drilling, changing the drill string, and surveying consumed the other 51 pct. These 

last three operations constitute available drilling time. Of the available 

drilling time in completing the rotary 

borehole, drilling consumed 42 pct and 

changing the drill string configuration, 

35 pct (table 4 and figure 13). Consequently, 35 pct of the drilling time was 

lost in changing the drill string configuration in order to maintain vertical 

borehole trajectory. In completing the 

second borehole, drilling consumed 77 pct 

of the available drilling time. The inhole motor did not need to be pulled 

out of the borehole to maintain vertical and horizontal trajectory. Surveying 

took the 23-pct balance of the available 

drilling time for both drilling methods. 

There were 21 productive drilling shifts 

of greater than 60 ft using the in-hole 

motor and only 11 during rotary drilling. 

The footage drilled during the in-hole 

TABLE 4. - Timestudy comparison of the two drilling methods 

NAp Not applicable. 

'60 ft or more drilled per shift. 

Available drilling time, pct: 

Drilling....... ...................... Surveying............................ 

Changing rotary drill string......... 

Productive shif tsl ..................... Average drilled per shift..........ft.. 

Worker-hours: 

Setup................................ 

Borehole completion.......... ........ Final depth...... .................. ft.. 

Rotary 

42 

23 

35 

11 

31.35 

108 

1,248 

1,242 

In-hole motor 

77 

23 

NAP 

2 1 

57.79 

156 

676 

1,557 
Rotary drilling ~n-nole moTor arllllng 

77 pct 

a71 Surveying 

FIGURE 13. - Available drilling time. 

motor and rotary drilling productive respectively. The worker-hours required 

shifts totaled 1,750 and 780 ft, respec- to set up the equipment and to complete 

tively. The average drilled footage per each borehole and the borehole final 

shift for rotary and in-hole motor drill- depths are provided in table 4. 

ing was 31.35 and 57.79 ft per shift, 

DRILLING COST COMPARISON 

The cost of initial capital equipment considered in the cost effectiveness calincluding the drill, power unit, and culation. Equipment costs unique to each 

drill rods amounted to $125,000 (table drilling method are shown in table 6. 

5). This equipment was common to both The cost comparison of rotary and in-hole 

drilling methods and consequently not motor drilling is exhibited in table 7. 

CONCLUSIONS 

In-hole motor drilling of horizontal 

boreholes for methane drainage in coal 

offered many advantages compared with rotary drilling. Inherently, drilling productivity was greater for in-hole motor 

drilling because it was not necessary to 

pull the drill string out of the borehole 

to change borehole direction or to sidetrack. As a result, 35 pct more of the 

available drilling time was occupied by 

drilling. This resulted in 11 more productive drilling shifts and an average of 

26 ft more drilled per shift. It also 

took 572 fewer worker-hours to complete 

the second borehole using the in-hole motor. After prorating the cost of the 

low-maintenance piston pumps needed to 

supply water to the in-hole motor, the 

in-hole motor drilling cost was $4.22/ft 

less than the cost of rotary drilling. 
TABLE 5 . . Initial drilling equipment costs. both rotary and in-hole motor 

Longyear drill and power unit ................................... BQ flush joint drill rod. 10 ft ea .............................. BQ stainless steel drill rod. 10 ft ea .......................... Hydraulic hose. 1-in ID. 100-ft sections ........................ 

Cost 

Drilling equipment costs: 

BQ water swivel ................................................. I 1 I 344 

Quantity 

BQ fishing tool ................................................. BQ box. NQ pin subs ............................................. NQ box. BQ pin subs ............................................. Miscellaneous: Handtools. air line. hydraulic oil. etc ......... Total ..................................................... Grouting standpipe. each borehole: 

Sandpiper (low pressure and high flow) .......................... 4-in-OD by 22-ft-long standpipe ................................. Thor handheld air drill. grout mixer ............................ 6-in-OD reamer .................................................. I 1 I 747 

Miscellaneous: Grout batch. wooden plug. low-pressure hose. 1 I 

1-in valve. etc ................................................ Total ..................................................... Gas handling. each borehole: 

During drilling: 

Bureau-designed gas-water separator ........................... I 11 207 

4-in-high pressure manual valve ............................... BQ or 2-3116-in-ID stuffing box ............................... 8-in-ID. 20-ft-long vent tubing ............................... Pipe fittings ................................................. After hole completion. putting borehole on production: I I 

Tank. gas-water . separator ..................................... I 1 I 159 

4-in-high pressure manual valve ............................... I I 301 

Pneumatic valve. 2-in ID ...................................... Venturi meter. 2-in ID ........................................ Float valves .................................................. Pipe fittings ................................................. Total ..................................................... / NAP 

Grand total ........................................ NAp Not applicable . 
TABLE 6. - Rotary and in-hole motor drilling equipment costs 

Rotary drilling equipment: 

18-ft NQ drill collar........................................... 

3-7116-in-OD centralizer........................................ 

3-112-in-OD 3-bladed drag bit (inserts)......................... 

Drag bit locking bowl, shank, and sub........................... 

BQ 1-way check valve............................................ 

Lease Sperry-Sun survey instrument ............................. 

Quantity Cost 

Miscellaneous................................................... 

Total...................................................... 

In-hole motor drilling equipment: 

Pumping system: 

Kerr triplex pump with motor.................................. 

High-pressure relief valves, control valves, pulsators, etc... 

High-pressure mechanical water flowmeter...................... 

Total...................................................... 

Drilling accessories: I * 7 

NQ 1-way check valve.......................................... 

3-112-in-OD tricone roller bits............................... 

Deflection shoe.. ............................................. 1 2 mo 1 600 

Lease Sperry-Sun survey instrument ........................... Lease Sperry-Sun extension bars, 1-112-in-OD.................. 

Total...................................................... 

Leasing Navi-Drill and accessories: 

2-314-in Navi-Drill in-hole motor............................. 

1,892 

2 mo 11,000 

TABLE 7. - Cost comparison of the two drilling methods 

Orienting sub................................................. 

Mule shoe..................................................... 

Total...................................................... 

NAp Not applicable. ' Includes mechanical device, camera, protective case. 

2 mo 

2 mo 

NAP 

Direct costs: 

Drilling and maintenance labor.............................. 18,249 

Payroll overhead4.. ......................................... 1 9,490 / 

120 

80 

11,800 

Drilling equipment1 ......................................... Lease Navi-Drill and accessories (2 mo)..................... 

Reconditioning equipment, parts............................. 

power. ...................................................... 1 354 1 718 

Rotary 

$7,511 

NAP 

1,375 

Indirect costs5 .............................................. Total cost............................................... 

Total drilled.............................................ft.. 

Cost per foot drilled6.. ...................................... $25.99 $21.77 

In-hole motor 

---- - - - - - - - 

NAp Not applicable. ' ~ncludes only equipment unique to each method. 

 h he in-hole motor equipment cost was calculated by dividing the cost of the pumping system (shown in table 6) by its minimum useful life of five boreholes and adding 

the cost of the drilling accessories. 

3$7,371 to recondition 2 Navi-Drills and $1,000 to repair electrohydraulic drill. 

4~ncludes all miner benefits. 

515 pct of drilling and maintenance labor and reconditioning equipment costs. 

6~nitial drilling equipment costs provided in table 5 are not included. 
REFERENCES 

1. Hagood, D.W., R.C. Pate, and 

J. W. Stevenson. Methane Control in an 

Advancing Section of an Underground Coal 

Mine (contract S0395033, Jim Walters Resources, Inc.). BuMines OFR 94-84, 1983, 

39 PP* 

2. Finfinger, G. L., and J. Cervik. 

Review of Horizontal Drilling Technology 

for Methane Drainage From U.S. Coalbeds. 

BuMines IC 8829, 1980, 20 pp. 

3. Deul, M., and J. Cervik. Methane Drainage in the Pittsburgh Coalbed. Paper in XVII International Conference of Mining Safety Research (Varna, 

Bulgaria, Oct. 3-7, 1977), pp. 9-15; 

available from S. J. Kravits, Pittsburgh Res. Cent., BuMines, Pittsburgh, 

PA. 

4. Prosser, L. J., Jr., G. L. Finfinger, and J. Cervik. Methane Drainage 

Study Using an Underground Pipeline, 

Marianna Mine 58. BuMines RI 8577, 1981, 

29 PP* 

5. Oyler, D. C., and W. P. Diamond. 

Drilling a Horizontal Coalbed Methane 

Drainage System From a Directional Surface Borehole. BuMines RI 8640, 1982, 

50 PP. 

6. Cervik, J., H. H. Fields, and G. N. 

Aul. Rotary Drilling Holes in Coalbeds 

for Degasification. BuMines RI 8097, 

1975, 21 pp. 

7. Stenberg, M., and L. Edling. Introduction to Directional Drilling Using 

the Navi-Drill, An Operation Manual. 

Boyles Bros. Drilling Co., Salt Lake 

City, UT, 1983, 30 pp. 

8. Thakur, P. C., and W. N. Poundstone. Horizontal Drilling Technology 

for Advance Degasification. Min. Eng. 

(N.Y.), v. 32, No. 6, 1980, pp. 676-6800 

9. NL Sperry-Sun (~klahoma City, OK). 

Magnetic Directional Single Shot Operating Instructions. 1972, 12 pp. 
would correspond directly with tool face 

direction) : 

A. Place survey disk on reader 

scale (fig. A-lB), with the thinnest 

copper margin facing up (fig. A-16'). 

B. Position disk so that bull's-eye 

circle is centered in reader circle with 

crosshairs lined up with hole direction 

line. 

C. Rotate disk until highest marked 

inclination line is located on top portion of reader circle toward the hole direction arrow. 

D. Finally, move disk up or down so 

that crosshairs are lined up with 90" 

left and right. 

E. Read tool face direction by extending scribe line to reader scale, 0' 

to 180" left or right. (To correct for 

photographic effects of the survey 

HOLE DIRECTION 

FIGURE A-1. - Reading film disks. 
hand-tight. The T-head or arrowhead on 

preceding this appendix. 

u 

Scale, in 

FIGURE A-2. - Survey hardware. Protective case (top), snubber (bottom left), mule shoe (bottom 

right). (Not shown are extension rods and survey instrument.) 

FIGURE A-3. - NL Sperry-Sun protective case, survey instrument, and snubber (left to right). 
in line. Four surveys are made after rotating the in-hole motor (tool face) from 

0' to 360" at 90" increments to verify 

that the scribe line correlates exactly 

with tool face direction. The alignment 

of the snubber, mule shoe, orienting sub, 

and deflection shoe used to survey for 

tool face directly is given in figure 

A-5. The method of assembling and the 

final alignment of these components may 

vary according to the practice of the 

driller. The main point is to determine 

the relation of the deflection shoe and 

the scribe line (9). - 

and fit onto snubber. Then place wireline-attached protective case over survey 

instrument and thread onto snubber (fig. 

A-3). Pump the surveying package down 

the drill rods. 

3. Remove the survey package from the 

borehole at the predetermined time. Look 

for a key imprint left on the tattletale. 

This indicates that a good survey was 

completed (fig. A-6) and the survey disk 

can be developed. Finally, replace the 

tattletale with a new lead tattletale for 

the next survey. 

BOREHOLE SURVEYING SETTING TOOL FACE DIRECTION USING 

THE TOOL FACE SETTING GUIDE 

1. Fit a lead tattletale (1/4-in OD, 

3/4-in in length) into the hole located 1. Remove the chalk line on the drill 

in the slot of the mule shoe (fig. A-6). rod (0°, as in paragraph 3, below), 
After 

0 A 4 

Scale, in 

FIGURE A-6. - Lead tattletale before and after completing a borehole survey. A, New tattletale 

instal led before survey; R, survey (mule shoe) impacts orienting sub during survey; C, key 

imprint from orienting sub left on tattletale after survey is completed. 

APPENDIX B.--DEFLECTION RATE COMPONENTS AND BIT PROJECTIONS 

A RULE-OF-THUMB METHOD FOR CALCULATING 

DEFLECTION RATE COMPONENTS FROM AN 

ESTABLISHED DEFLECTION RATE MAGNITUDE 

A rule-of-thumb for determining the 

break down of the deflection rate magnitude for quadrants 1 and 2 (table B-1) 

was to calculate the ratio of the tool 

face setting with 90" and then multiply 

by the deflection rate magnitude. This 

number equaled the horizontal component 

(right or left) of the deflection rate 

magnitude. The build rate or vertical 

component then equaled the deflection 

Examples of calculating vertical and 

horizontal components corresponding to 

tool face settings follow. Conditions 

are 

Interval drilled......... 337-367 ft 

Survey depth............. 337 ft 

Inclination at survey 

depth................... 87.7" 

Bearing at survey depth.. S 84.5" W 

Tool face................ 130" right 

Bit depth................ 367 ft 

Material drilled......... Co a1 

rate magnitude minus the horizontal One-step vertical projection of bit at 

component. 367 ft: 

To calculate the horizontal component 

of the deflection rate magnitude for tool 

face settings in quadrants 3 and 4, the 

tool face setting was subtracted from 

180°, then divided by 90°, and finally 

multiplied by 0.10" per foot. The vertical component of the deflection rate was 

simply the horizontal component subtracted from the deflection rate magnitude. A table of calculated deflection 

rates corresponding to tool face settings 

can be found in the main text (table 3). 

Established deflection rate vertical 

component of tool face at 130" right 

= -0.044" per foot (table 3). Effect on 

borehole trajectory in vertical plane 

from survey depth to bit depth = -0.044" 

per foot x 30 ft = -1.32". 

Inclination at survey depth.. 87.70" 

Change in inclination, survey 

depth to bit depth.......... -1.32" 

Projected inclination at bit 

depth....................... 86.38" 

TABLE B-1. - Calculating deflection rate components 

Tool face 

setting 

(fig. 11) I Horizontal component I component I degree I degree 

Quadrant 

I 

No. 

I per foot I per foot 

30' right. / 1 1 - x 0.10.. ............ / ~0.10 . 0.0331 0.033 right / 0.067, build. 

Deflection rate components 

Calculation - 

I Vertical 

NAp Not applicable. 'DRHc = 90 x DR. 

30" left.. 

145" right 

145" left. 

NOTE.--TFS = tool face setting; DR = deflection rate magnitude. 

Horizontal 

component, 

Vertical 

component, 

TUC 

2 

4 

3 

Same as 30" right....... 

3[(18~ - 145)/90] x 0.10 

Same as 145" right...... 

NAP.......... 

20.10 - 0.039 

NAP.......... 

0.033 left. 

0.039 right 

0.039 left. 

0.067, build. 

0.061, drop. 

0.061, drop. 
Angle averaging to project change in vertical position from survey depth to bit 

depth: 

Vertical = sin ([(inclination at beginning - horizontal inclination 

deviation of interval of 90" 

projected inclination - horizontal interval 

at end of interval of 90" drilled 

= sin ([(87.7" - 90") + (86.38" - 90°)]/2) x 30 ft 

= -1.54 ft. 

Therefore, projected change in vertical position from survey depth to bit depth is 

-1.54 ft, drop. (Refer to figure 5B in the main text, vertical deviation plot of 

borehole 2.) 

One-step horizontal bit projection at a depth of 367 ft: 

Horizontal component of deflection rate of tool face at 130" right = 0.056" per 

foot right. Effect on borehole trajectory in horizontal plane from survey depth to 

bit depth = 0.056" per foot x 30 ft = 1.68" right. 

Bearing at survey depth...............,..... S 84.5" W 

Change in bearing, survey depth to bit depth +1.68" right 

Projected bearing at bit depth.......,...,,. S 86.18" W 

Angle averaging: 

bearing at beginning - west bearing, 

Sin ( [( of interval S 90" W 

projected bearing - west bearing3] / 2) interval 

+ (at end of interval S 90" W X drilled 

= projected change in latitude from beginning to end of interval 

= sin ([(84.5" - 90") + (86.2" - 90°)]/2) x 30 ft 

= -2.43 ft, change in latitude. 

Projected change in departure = (interval length2 - change in latit~de~)~/~ 

= -29.90 ft (west departure is negative). 
EXAMPLES OF TWO TYPES OF TWO-STEP VERTICAL BIT PROJECTIONS 

Type A two-step vertical projection of 517 ft: 

A type A two-step vertical bit projection (tool face direction is not changed for 

next drilling interval) is very similar to a one-step vertical projection calculation, as shown here. Conditions are 

Intervals drilled.......,.... 437-467 ft, 467-517 ft 

Survey depth...... ........... 437 ft 

Inclination at survey depth.. 88.0" 

Tool face.................... 65" left 

Deflection rate vertical component for tool face of 65" left = 0.028" per foot 

build (table 3). Projected change in inclination from 437 to 517 ft = +0.028" per 

foot x 80 ft = +2.24". 

Inclination at survey depth.......... 88.0" 

Projected change in inclination...... +2.24" 

Projected inclination at 517 ft...... 90.24" 

Change in vertical position from depth of 437 to 517 ft by angle averaging: 

Sin ([(88.0° - 90") + (90.24" - 90°)]/2) x 80 ft 

= -1.23 ft drop, 437 to 517 ft (fig. 5B). 

Type B two-step vertical bit proiection: 

At a bit depth of 717 ft, drilling stopped and an inclination of 89.1" at the survey depth of 687 ft was determined. Using the vertical deflection rate of +0.022" 

per foot build for a tool face of 70" left, the projected inclination at 717 ft was 

calculated to be 89.8". The one-step vertical projection produced a 0.29-ft drop in 

vertical position during the already drilled interval of 687 to 717 ft. The next 

borehole interval of 717 to 757 ft was to be drilled with a tool face setting of 110" 

left. Therefore, the type B two-step vertical projection was calculated as shown: 

Projected inclination at 717 ft............. 89.80" 

Projected change in inclination, 

717 to 757 ft (0.022" per foot x 40 ft).... -.88" 

Projected inclination at 757 ft............. 88-92" 

Change in vertical position from depth of 717 to 757 ft by angle averaging: 

Sin ([(89.8" - 90") + (88.9" - 90°)]/2) x 40 ft 

= -0.45 ft drop, 717 to 757 ft (fig. 5B). 
the rotary drilling parameters during 

reaming (table 1 in main text). From the 

beginning of the first reaming pass to 

the end of the third pass, there will be 

a gradual increase in the volume of coal 

cuttings and a darkening in color in the 

drill effluent. The bottom side of the 

borehole is being worn deeper and deeper, 

from the completion of the first to the 

third reaming pass (fig. B-1). After the 

third pass has been completed, a drill 

rod is added and the fourth reaming pass 

can begin. Caution must be taken to advance the in-hole motor slowly during the 

beginning of the fourth pass to prevent 

jumping over the kerf that was worn during the first three reaming passes. If 

this does happen, the face of the kerf 

will be rounded off and the sidetracking 

procedure might have to be repeated at 

another borehole depth. 

Five sidetracks were completed with the 

in-hole motor. As experienced in drilling the first sidetrack from a depth of 

g 

227 to 241 ft, the fourth pass needed to 

be only 4 ft long to complete the sidetrack (fig. - Thrust levels were 

increased substantially during the fourth 

reaming pass to maintain the penetration 

rates of passes one through three. It is 

believed that the decrease in penetration 

rate in the fourth pass resulted because 

the last 4 ft of the rear end of the inhole motor were binding against the high 

side of the old borehole (fig. B-1). 

This resistance continued until the 4-ftlong fourth reaming pass was completed 

and the in-hole motor and bit, which were 

14 ft long, occupied the 14-ft sidetrack. 

Consequently, a maximum bending stress 

occurred on the first BQ rod directly 

behind the in-hole motor where it was 

threaded into the orienting sub. 

By the completion of the fourth reaming 

pass, the drilling effluent will consist 

entirely of coal cuttings in suspension. 
Before drilling is resumed, a final check 

is made to ensure that the sidetrack 

was successful. All rotation and thrust 

are shut off. Then the in-hole motor 

is thrust slowly (about 400 to 500 lb) 

forward. If a new borehole has been 

started, the end of the new borehole will 

be hit immediately and a rapid increase 

in thrust pressure will be observed at 

the drill. When the test is successful, 

backward thrust is applied immediately to 

prevent the drill rod from breaking in 

the borehole. 

The following are examples of sidetrack 

projections: The inclination at 403 ft 

was previously surveyed as 89.8O. The 

inclination at 407 ft was projected to 

be 90.0". When the beginning of the 

sidetrack occurred between previously 

surveyed depths or locations, the inclination was estimated using a one-step 

projection technique. For the 14 ft of 

completed sidetrack, the vertical deflection rate of 0.10' per foot drop for a 

tool face of 180' was assumed, and therefore, a drop in inclination of -1.4' 

could be expected. Knowing the inclination at the beginning of the sidetrack 

and estimating the inclination at the end 

of the sidetrack (inclination at beginning of sidetrack minus 1.4'), the effect of vertical position from the sidetrack was determined. This projection is 

called a one-step sidetrack vertical projection. The one-step sidetrack projection for the sidetrack from 407 to 421 ft 

was a 0.17-ft drop in vertical position 

(fig. 5B). The next drilling interval of 

421 to 437 ft was going to be drilled 

with a tool face setting of 120" left. 

Using the projected inclination at 421 

ft, a two-step sidetrack vertical projection was made for the bit at 437 ft (fig. 

5B). Drilling continued to a depth of 

437 ft, and another survey was taken, 

followed by one- and two-step vertical 

projection at 437 and 467 ft. The previous one-step sidetrack vertical projection at 421 ft was found to be within one 

borehole diameter of the plotted vertical 

position. Later, as drilling advanced, 

the sidetrack projections at 437 ft was 

determined to be 0.3 ft from the plotted 

trajectory. The sidetrack vertical projection technique was used during each of 

the three remaining sidetracks at depths 

of 821, 1,187, and 1,427 ft (fig. 5B). 
Footage 

drilled 

70 

70 

10 

36 

60 

60 

60 

40 

20 

30 

40 

40 

10 

20 

40 

40 

646 

20 

90 

60 

20 

30 

20 

50 

0 

30 

0 

80 

70 

30 

20 

0 

40 

20 

30 

10 

0 

0 

70 

690 

0 

90 

0 

10 

50 

0 

0 

0 

0 

20 

30 

200 

1. 536 

NAp 

NAp 

Portal 

to 

portal. 

min 

100 

120 

120 

100 

135 

90 

100 

100 

130 

105 

140 

140 

115 

105 

105 

105 

1. 810 

105 

9 5 

105 

125 

115 

90 

100 

9 5 

80 

9 0 

9 5 

9 0 

115 

105 

105 

130 

9 5 

105 

9 5 

7 5 

110 

100 

2. 220 

100 

9 5 

130 

115 

120 

100 

105 

9 5 

135 

9 5 

155 

1. 245 

5. 275 

NAp 

22.43 

Downtime. 

min 

135 

120 

140 

110 

135 

90 

13 5 

115 

130 

105 

160 

140 

335 

105 

105 

120 

2. 563 

40 

4 0 

135 

4 5 

155 

100 

80 

5 5 

120 

7 0 

6 5 

45 

3 0 

100 

7 5 

115 

60 

105 

9 5 

17 5 

370 

15 

1. 950 

380 

20 

9 0 

15 

4 0 

15 

110 

105 

180 

315 

120 

1. 615 

- - 

6. 268 

NAP 

26.65 

Available 

drilling 

time. min 

145 

217 

325 

125 

215 

315 

245 

90 

27 5 

310 

300 

24 5 

10 

9 5 

265 

130 

3. 307 

335 

345 

240 

310 

210 

290 

300 

330 

280 

320 

320 

345 

335 

275 

300 

235 

325 

270 

290 

230 

0 

365 

6. 250 

0 

365 

260 

350 

320 

140 

265 

280 

165 

7 0 

20 5 

2. 420 

11. 977 

NAP 

50.92 

total time . 

OF 

drilling 

Surveying. min 

100 

108 

29 

7 1 

6 3 

60 

6 0 

30 

35 

50 

175 

130 

0 

60 

110 

2 5 

1. 106 

6 5 

90 

100 

0 

7 0 

105 

6 5 

3 0 

100 

0 

14 5 

125 

120 

6 5 

0 

3 5 

130 

4 0 

3 0 

0 

0 

40 

1. 355 

0 

100 

40 

0 

7 0 

0 

0 

0 

0 

0 

3 5 

245 

- -- 

2. 706 

22.59 

11.51 

time . 

Date 

February: 

3 ........ 

4 ........ 

5 ........ 

8 ........ 

9 ........ 

10 ....... 11 ....... 

16 ....... 17 ....... 

18 ....... 19 ....... 2 2 ....... 2 3 ....... 2 4 ....... 2 5 ....... 26 ....... 

Total .. 

March: 

1 ........ 

2 ........ 

4 ........ 

5 ........ 

8 ........ 

9 ........ 

10 ....... 11 ....... 12 ....... 15 ....... 16 ....... 17 ....... 18 ....... 19 ....... 2 2 ....... 2 3 ....... 2 4 ....... 2 5 ....... 2 6 ....... 2 9 ....... 30 ....... 3 1 ....... 

Total .. April: 

2 ........ 

5 ........ 

6 ........ 

7 ........ 

8 ........ 

9 ........ 

12 ....... 13 ....... 15 ....... 16 ....... 2 0 ....... 

Total .. Grand 

total . pct of ADT' 

pct of TT' . NAp Not 

EACH BOREHOLE 

timestudy 

Stabilizer 

position 

change. 

mi n 

0 

89 

290 

30 

0 

0 

0 

0 

185 

120 

0 

0 

0 

0 

0 

0 

7 14 

230 

90 

0 

28 0 

0 

0 

0 

300 

3 0 

320 

0 

0 

0 

0 

300 

0 

0 

0 

250 

230 

0 

180 

2. 210 

0 

0 

220 

225 

0 

140 

265 

280 

165 

0 

0 

1. 325 

4. 249 

35.48 

18.07 

2~ercent of 

APPENDIX 

TABLE C.1 . Equipment 

operating 

time. h 

5.00 

5.00 

5.67 

5.50 

3.67 

6.50 

4.75 

5.75 

5.17 

5.17 

5.33 

5.00 

. 42 

1.50 

5.75 

6.00 

76.18 

5.75 

6.25 

5.00 

5.75 

5.00 

5.00 

6.00 

6.00 

5.50 

6.00 

5.50 

6.00 

5.50 

6.00 

5.00 

5.75 

6.00 

6.00 

6.00 

6.00 

. 00 

6.25 

120 

0 

6.25 

5.50 

6.00 

5.75 

3.00 

6.00 

5.00 

5.5 

2.0 

3.5 

48.5 

245 

NAP 

NAP 

available 

C.--TIMESTUDIES 

. Rotary 

Actual 

drilling. min 

4 5 

2 0 

6 

2 4 

152 

255 

185 

60 

55 

140 

125 

115 

10 

3 5 

155 

105 

1. 487 

4 0 

165 

140 

3 0 

140 

185 

235 

0 

150 

0 

175 

2 20 

215 

2 10 

0 

200 

19 5 

230 

10 

0 

0 

145 

2. 685 

0 

265 

0 

9 5 

250 

0 

0 

0 

0 

7 0 

17 0 

850 

5. 022 

41.93 

21.35 

drilling 

Workerhours 

24 

24 

24 

16 

16 

16 

16 

24 

24 

24 

24 

24 

16 

16 

24 

16 

328 

24 

24 

24 

24 

24 

32 

2 4 

16 

16 

32 

3 2 

32 

24 

24 

32 

24 

24 

32 

24 

32 

32 

3 2 

584 

24 

32 

32 

32 

32 

32 

24 

32 

32 

32 

32 

336 

1. 248 

NAp 

NAp 

of 

Work 

Length, 

min 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

7. 680 

(16 shifts) 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

10. 560 

(22 shifts) 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

5. 280 

(11 shifts) . 

49 shifts 

NAp 

NAp 

applicable . 

shift 

Crew 

size 

3 

3 

3 

2 

2 

2 

2 

3 

3 

3 

3 

3 

2 

2 

3 

2 

NAp 

3 

3 

3 

3 

3 

4 

3 

2 

2 

4 

4 

4 

3 

3 

4 

3 

3 

4 

3 

4 

4 

4 

NAp 

3 

4 

4 

4 

4 

4 

3 

4 

4 

4 

4 

NAp 

NAP 

NAp 

Nap 

'percent 
NAp Not applicable . 'percent of available drilling time . 2~ercent of total time . 

aU.S. GPO: 1985.505.019/20, 015 

Footage 

drilled 

5 5 

15 

45 

8 6 

7 4 

3 0 

5 0 

2 0 

3 0 

405- 

30 

7 0 

40 

7 0 

20 

0 

8 0 

3 0 

7 0 

9 0 

60 

120 

120 

7 0 

0 

8 70 

0 

2 0 

2 0 

7 0 

110 

120 

50 

60 

7 0 

20 

6 0 

9 0 

100 

6 0 

100 

950 

2. 225 

NAp 

NAp 

Downtime. 

min 

2 7 0 

0 

145 

100 

30 

120 

8 5 

185 

150 

1. 085 

205 

110 

9 0 

4 5 

310 

325 

165 

135 

2 0 

130 

135 

3 0 

50 

7 0 

390 

2. 210 

375 

225 

210 

8 0 

0 

40 

160 

2 15 

9 0 

260 

110 

8 0 

6 0 

0 

0 

1. 905 

3. 985 

NAP 

28.13 

Available 

drilling 

time. min 

120 

180 

245 

275 

335 

240 

320 

160 

240 

2. 115 

185 

290 

300 

345 

7 5 

30 

225 

225 

355 

245 

255 

360 

315 

305 

0 

3. 510 

0 

150 

175 

305 

380 

345 

240 

16 5 

255 

115 

285 

295 

320 

385 

380 

3. 795 

9. 420 

NAP 

50.97 

Portal 

to 

portal. 

min 

90 

6 0 

9 0 

105 

115 

120 

7 5 

135 

90 

880 

9 0 

80 

90 

90 

9 5 

125 

9 0 

120 

105 

105 

9 0 

9 0 

115 

105 

9 0 

1. 480 

105 

105 

9 5 

9 5 

100 

9 5 

8 0 

100 

135 

105 

8 5 

105 

100 

9 5 

100 

1. 500 

5. 200 

NAp 

20.89 

Date 

December: 

7 ........ 

10 ....... 13 ....... 

14 ....... 

15 ....... 

16 ....... 17 ....... 

2 0 ....... 2 1 ....... 

Total .. 

January : 

3 ........ 

4 ........ 

5 ........ 

6 ........ 

7 ........ 

14 ....... 

17 ....... 

18 ....... 

19 ....... 2 0 ....... 2 1 ....... 2 6 ....... 

2 7 ....... 2 8 ....... 3 1 ....... 

Total .. 

February : 

1 ........ 

2 ........ 

3 ........ 

4 ........ 

7 ........ 

8 ........ 

9 ........ 

11 ....... 14 ....... 15 ....... 

16 ....... 

18 ....... 2 2 ....... 2 3 ....... 2 5 ....... 

Total .. 

Grand 

total . pct of ADT' 

pct of TT* . 

motor drilling 

Surveying. min 

30 

3 0 

4 0 

9 5 

110 

4 0 

100 

6 0 

60 __ 

565 

45 

7 0 

4 0 

7 0 

25 

30 

8 5 

7 5 

7 5 

7 5 

60 

6 5 

55 

70 

0 

840 

0 

4 0 

2 0 

5 5 

85 

7 0 

60 

3 5 

6 5 

3 5 

40 

6 5 

45 

9 0 

45 

750 

2. 155 

23.00 

11.66 

timestudy 

Stabilizer 

position 

change. 

mi n 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP-P . 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAP 

NAp 

NAp 

NAp 

NAp 

In-hole 

Actual 

drilling. min 

90 

150 

205 

18 0 

225 

200 

220 

100 

1. 550 

140 

220 

260 

275 

50 

0 

140 

150 

280 

170 

19 5 

295 

260 

235 

0 

2. 670 

0 

110 

155 

250 

29 5 

275 

180 

130 

190 

8 0 

24 5 

230 

275 

295 

335 

3. 045 

7. 265 

77.00 

39.31 

C.2 . . 

Equipment 

operating 

time. h 

2.25 

3.00 

4.75 

5.25 

6.00 

4.00 

6.00 

3.00 

5.00 

39.25 

5.00 

5.00 

6.00 

6.00 

6.00 

4.50 

6 . 00 

6.00 

6.00 

4.00 

4.00 

6.00 

5.00 

6.00 

5.50 

81.0 

5.00 

5.00 

5.00 

5.00 

6.00 

6.00 

6.00 

6.25 

4.25 

2.00 

5.00 

5.25 

5.50 

6.00 

5.50 

77.75 

198 

NAP 

NAP 

TABLE 

Workerhours 

24 

12 

2 4 

16 

16 

24 

16 

24 

24 

- 180 

16 

16 

16 

16 

2 4 

2 4 

16 

16 

16 

16 

16 

16 

16 

16 

16 

256 

16 

16 

16 

16 

16 

16 

16 

16 

16 

16 

16 

16 

16 

16 

16 

240 

676 

NAP 

NAp 

Work 

Length. 

mi n 

480 

240 

480 

480 

480 

480 

480 

480 

480 

4. 080 

(9 shifts) 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

7. 200 

(15 shifts) 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

480 

4 80 

480 

480 

480 

7. 200 

(15 shifts) 

39 shifts 

NAp 

NAp 

shift 

Crew 

size 

3 

3 

3 

2 

2 

3 

2 

3 

3 

NA~ 

2 

2 

2 

2 

3 

3 

2 

2 

2 

2 

2 

2 

2 

2 

2 

NAp 

2 

2 

2 

2 

2 

2 

2 

2 

2 

2 

2 

2 

2 

2 

2 

NAp 

NAp 

NAp 

NAp