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Eastern Macedonia and Thrace Institute of Technology
MSc in Oil & Gas Technology
“Drilling Engineering”
“Project in Drilling Engineering”
Iliopoulos P.
Tsiknopoulos K.
Ballis. Th.
Supervisor: Gaganis B.
June 2015
Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
Table of Contents
Casing design..................................................................................................................................3
Axial Loading..............................................................................................................................4
Tension...................................................................................................................................5
Compression...........................................................................................................................6
Burst/Collapse............................................................................................................................7
Drill string dimensions....................................................................................................................9
HYDRAULICS.................................................................................................................................14
Hoisting system............................................................................................................................16
Appendix......................................................................................................................................18
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
Casing design
The answer to the question (5a) is included at the excel spreadsheet that was given as
an input for this project and is illustrated at the next table.
For the next question we have created the appropriate chart using the table in the
appendix which clearly shows the minimum number of casing strings needs to be placed
from top to bottom of our wellbore. In order to do so we have determine the EMD
while we have taken into account the minimum safety margin. (EMD pore + 0.5 = EMD
margin pore) and (EMD fracture -0.5 = EMD margin)
Figure 1 Mud density line
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
According to the previous chart we are able to decide about three casing strings taking
into account the initial casings (conductor, surface). So we created a model which has
five casings. Their dimensions were selected from the SPE textbook and the sample
charts that were given. Also we must take into account the corresponding mud density
and the buoyancy factor because we further want to calculate the stresses with the wet
weight.
Table 1 Casing design
Casings Depth(ft) OD Bit
CASING OD (in)
Mud Density
Buoyancy
Factor
Weight Grade
Casing ID (in)
Conductor 0 - 100 - 30 9,6 0,853 234,29 X-52 28,5
Surface casing 0 - 2000 26 20 9,6 0,853 94 H-40 19,124
1st
intermediate 0- 5800 17,5 13,375 9,6 0,853 68 C-90 12,415
2nd
intermediate 0 - 10100 12,25 9,625 15 0,771 40 C-90 8,835
Production liner
9900 - 13000 7,875 5,5 16,4 0,749 23 C-90 4,67
Axial Loading
F = ((D-L)*(Wa * BF) + Fpull)*2
Where, safety factor = 2
Wa = Casing Weight
Fpull = overpull force and BF = (1-ρmρ s
)
Ften = π4 σyield (OD2 – ID2)
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
Tension
Conductor
F = ((100 * 234.29 * 0.853) + 10000) * 2 = 59969.9 lbf
Ften = π/4 * 52000*(302 – 28.5 2) = 3583771.8 lbf
Ften > F Can withstand the stress
Surface casing
F = ((2000 * 94 * 0.853) + 10000) * 2 = 340728 lbf
Ften = π/4 * 40000*(202 – 19.1242) = 1076706.2 lbf
Ften > F Can withstand the stress
1 st intermediate
F = ((5800 * 68 * 0.853) + 10000) * 2 = 692846.4 lbf
Ften = π/4 * 90000*(13,3752 – 12.4152) = 1750068.17 lbf
Ften > F Can withstand the stress
2 st intermediate
With H-40
F = ((10100 * 32.3 * 0.771) + 10000) * 2 = 523046.7 lbf
Ften = π/4 * 40000*(9.625 2 – 9.0012) = 365.135 lbf
Ften < F Cannot withstand the stress
With C-90
F = ((10100 * 40 * 0.771) + 10000) * 2 = 642.968 lbf
Ften = π/4 * 90000*(9.625 2 – 8.835 2) = 1030839.8 lbf
Ften > F Can withstand the stress
Production liner
F = ((3100 * 23 * 0.749) + 5000) * 2 = 116807.4 lbf
Ften = π/4 * 90000*(5.52 – 4,672) = 596666.2 lbf
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
Ften > F Can withstand the stress
Compression
Conductor
F = 100 * 234.29 = 23429 lbf
Ften = π/4 * 52000*(302 – 28.5 2) = 3583771.8 lbf
Ften > F Can withstand the stress
Surface casing
F = 2000 * 94 = 188000 lbf
Ften = π/4 * 40000*(202 – 19.1242) = 1076706.2 lbf
Ften > F Can withstand the stress
1 st intermediate
F = 5800 * 68 = 394400 lbf
Ften = π/4 * 90000*(13,3752 – 12.4152) = 1750068.17 lbf
Ften > F Can withstand the stress
2 st intermediate
With H-40
F = 10100 * 32.3 = 326230 lbf
Ften = π/4 * 40000*(9.625 2 – 9.0012) = 365.135 lbf
Ften < F Can withstand the stress
With C-90
F = 10100 * 40 = 404000 lbf
Ften = π/4 * 90000*(9.625 2 – 8.835 2) = 1030839.8 lbf
Ften > F Can withstand the stress
Production liner
F = 3100 * 23 = 71300 lbf
Ften = π/4 * 90000*(5.52 – 4.672) = 596666.2 lbf
Ften > F Can withstand the stress
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
After the above calculations we conclude that instead of using H-40 type to the 2 st
intermediate casing, we use C-90.The worst case scenario is obviously on tension loadings.
Burst/Collapse
We assume a gas density of 3 ppg in case of a kick.
Internal pressure: Pi = 0.052 * ρgas * L
Maximum burst pressure: Pbr = 0.875 2t σ yielddn
External pressure: Pf = 0.465 * Depth
Table 2 Burst calculations
Depth (ft) Pe (psi) Pff (psi) Pi (psi)
Burst Pressure
(psi)
Max Pburst (psi)
Result
Surface casing0 0 998,4 686,4 686,4
1530 Accept2000 930 998,4 998,4 68,4
1st Intermidiate casing
2000 930 4575,272 3982,472 3052,472
5652 Accept4000 1860 4575,272 4294,472 2434,472
5800 2697 4575,272 4575,272 1878,272
2st Intermidiate casing
5800 2697 8734,076 8063,276 5366,276
6464 Accept8000 3720 8734,076 8406,476 4686,476
10100 4696,5 8734,076 8734,076 4037,576
Production Liner 9900 4603,5 11573,12 11089,52
6486,02 11884 Accept
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
10100 4696,5 11573,12 11120,72 6424,22
13000 6045 11573,12 11573,12 5528,12
Table 3 Stress combination
Depth (ft)
Inner P Outer PAxial Load
AreaAxial stress
σt termσz
termellipse result
0 14,7 0 188000 26,91766 6984,263 0,008578 0,175 0,02922000 14,7 998,4 0 26,91766 0 -0,57404 0,0004 0,32972000 14,7 998,4 258400 19,4452 13288,63 -0,15795 0,1478 0,07014000 14,7 1996,8 122400 19,4452 6294,612 -0,31826 0,0701 0,12855800 14,7 2895,36 0 19,4452 0 -0,46253 0,0002 0,2145800 14,7 4524 172000 11,45378 15016,88 -0,63656 0,167 0,53948000 14,7 6240 84000 11,45378 7333,826 -0,8788 0,0817 0,850710100 14,7 7878 0 11,45378 0 -1,11003 0,0002 1,23239900 14,7 8442,72 71300 6,629624 10754,76 -0,67118 0,1197 0,545110100 14,7 8613,28 66700 6,629624 10060,9 -0,68476 0,112 0,558113000 14,7 11086,4 0 6,629624 0 -0,88171 0,0002 0,7776
Production Liner
Accept
Accept
Unaccept
Accept
1st Intermidiat
e casing2st
Intermidiate casing
Surface casing
Stress Combination
After completing the previous calculations we found out that our second intermediate
casing cannot withstand the total load according to the elliptic equation.
According to the given formula: σz term2 + σt term2 - σt term2* σz term2 >1 So we
conclude to change the dimensions of that casing from C-90 to C-95.
Table 4 New casing design
Casings Depth(ft) OD Bit
CASING OD (in)
Mud Densit
y
Buoyancy
Factor
Weight
Grade Casing ID (in)
Conductor 0 - 100 - 30 9,6 0,853 234,29 X-52 28,5
Surface casing
0 - 2000 26 20 9,6 0,853 94 H-40 19,124
1st
intermediate0- 5800 17,5 13,375 9,6 0,853 68 C-90 12,415
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
2nd
intermediate0 -
1010012,2
59,625 15 0,771 40 C-95 8,835
Production liner
9900 - 13000
7,875
5,5 16,4 0,749 23 C-90 4,67
Drill string dimensions
Table 5 Given data
Specifications OD ID weight Steel density
Drill pipe 5’’ 4,276’’ 19,5lbf/ft 490lbm/ft3
Drill collars 5’’ 2,5’’
Having into account all the given specifications for drill pipe and drill collars, it is
absolutely necessary to determine the suitable lengths. These lengths should ensure
that during the drilling process any point of drill pipe is not under compression and any
point of drill collars is not under tension. Different WOB at three stages, give us detailed
information in order to locate exactly the point (neutral point) above which there is not
tendency to buckling. The correct position which satisfies the previous restrictions is the
top of the collars.
EQUATIONS
Minimum drill collars length: Ldc= Fb/Wdc*BF
Stability force: Fs(depth)= AiPi-AoPo
Wdc = π/4(OD2-ID2)
Ft=Wdp*Ldp+Wdc*Ldc+0,052*ρmud*(D-Ldc)*(Adc-Adp)-0,052*ρmud*D*Adc-WOB
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
BF = 1 – Mud density65,5lbm /gal
Where:
OD,ID= external and internal diameter
Pi= internal pressure
Po=external pressure
Fb=WOB
65,5= weigth og a gallon of steel
Calculations
Wdc=π/4*((52−2,52)/0,2945)=50,1lbf/ft
490lbm/ft3=65,5lb/gal
For 5800ft
BF = 0,853
L=Fb
Wdc(1− PfPs
)=Fb
Wdc∗BF= 25000 lbf50,1∗0,85= 587ft = 590ft
For 10100ft
BF=0,771
L = Fb
Wdc (1− PfPs
) =Fb
Wdc∗BF= 50000lbf
50,1 lbfft
∗0,77= 769ft=770ft
For 13000ft
BF=0,749
L =Fb
Wdc(1− PfPs
)=Fb
Wdc∗BF= 75000 lbf
50,1 lbfft
∗0,749 = 1999ft=2000ft
The previous calculations were conducted using an outer drill collar diameter equal to
5’’. Using Wdc=50,1lbf/ft and the above minimum drill collars lengths at the excel file
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
we observed that a larger OD collar is required, in order to avoid any segment of our
drill pipe to be under compression. So we selected a collar with OD equal to 8’’.
Unfortunately the suitable ID diameter of our production liner is equal to 4.67’’, but
using this ID we can’t use any of the previous collar diameters. In order to proceed
with tis project we assume an OD of the drill collars equal to 8’’.
New Wdc = 155 lbf/ft
For 5800 buckling
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
-200000 -100000 0 100000 2000000
1,000
2,000
3,000
4,000
5,000
6,000
7,000
Axial forces, lbfD
epth
, ft
For 10100 buckling
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
-600000 -400000 -200000 0 200000 4000000
2,000
4,000
6,000
8,000
10,000
12,000
Axial forces , lbf
Dep
th,
ft
For 13000 buckling
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
-1000000 -500000 0 5000000
2,000
4,000
6,000
8,000
10,000
12,000
14,000
Axial forces, lbf
Dep
th, f
t
Grade of the drill pipes
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
The following formula give us the opportunity to select the suitable grades of drill pipes while includes the wet weight of drill string an over pulling force at all depths
F’t= (Wcd*Ldc+Wdp*Ldp)*BF+ pulling force
σi= F’t/A
Where : σι > σyield
Table 6 Drill string dimensions and specifications
DEPTH WOB Ldc Ldp Ft(lbf) GRADES
5800 25000 590 5210 264667 D-55
10100 50000 770 9330 332290 E-75
13000 75000 2000 11000 492850 X-95
HYDRAULICS
EQUATIONS
For the calculations we assumed a sphericity ψ = 0.801, the mean diameter of the
cuttings equal to 0.0025”.
The flow rate is 400 gal/min
Slip velocity using stokes model: Us =138( ps−pf )d2
μ
Annular velocity: Ua =q
2.448∗(d2−d2)
pipe velocity: Udp =q
2.448∗d2
total nozzle area: At = 3*π/4*(13/32)
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
Δpbit =8.311∗10−5∗p∗q2
cd2∗A tot
2
Neutonian friction pressure loss
There exist several rheological fluids models such as Bingham Plastic Model, Power Law
Mode, Robertson-Stuff Model and Herschel-Bulkley Model using fluid hydrodynamics.
Some of them are utilized to characterize drilling fluids while some are not applicable to
drilling fluids. In this assignment we assume that the drilling mud is a Newtonian fluid.
Pipe: dPfdL
= μ v1500d2
Annulus: dPfdL
= μ v1500(d¿¿2−d1)
2¿
Mud pump pressure: Ppwp = Ps + Pd + Pa + Pd, where Ps is the Surface equipment pressure loss and we assume that is equal to zero.
Table 7 Required pump pressure
DepthU
annulus pipe
U anullu
s collar
Udp UdcAt
nozzleInitial slip U
F Nre New FFinal slip U
Pressure loss DPbit
Pressure loss
Dppipe
Pressure loss
Dpanullus
Recuired pump
pressure Ppwp
0-2000 0.48 0.54 8.94 26.14 0.33 0.21 2.59 9.27 170.00 0.03 1289.71 6.34 0.17 1296.212000-5800
1.27 1.81 8.94 26.14 0.33 0.21 2.59 9.27 170.00 0.03 1289.71 16.71 7.63 1314.05
5800-10100
3.08 11.62 8.94 26.14 0.33 0.11 3.00 7.99 200.00 0.01 2015.16 25.94 1141.54 3182.64
10100-13000
4.41 17.56 8.94 26.14 0.33 0.09 3.48 6.90 230.00 0.01 2203.25 45.81 1300.00 3549.05
All the above calculations have been conducted with a viscosity of 5 cp, so that the mud
velocity is always greater than the slip velocity at all different depths.
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
Hoisting system
At this stage we should compute the maximum expected load which stresses the
hoisting system during the drilling process. We consider two different scenarios for the
drill string and casing strings, while we assume an extra pull load of 20000 psi and
10000 psi respectively.
Table 8 Maximum load from drill string
Depth (ft)
Pipe (ft)Weight (lbf/ft)
Collars (ft)
Weight (lbf/ft)
Total pipe (lbf)
Total collar (lbf)
Mud (ppg)
Extra Pull load (lbf)
Wet weight
(lbf)
Total weight (lbf)
2000 1750 250 155 34125 38750 9.6 20000 62194.08 82194.08
5800 5210 590 155 101595 91450 9.6 20000 164751.38 184751.38
10100 9930 770 155 193635 119350 15 20000 241309.05 261309.05
13000 11000 2000 155 214500 310000 16.4 20000 393174.81 413174.81
19.5
Table 9 Maximum load from casings
Depth (ft)
Weight (lbf/ft)
Weight (lbf/ft)
Weight (lbf/ft)
Total casing (lbf)
Mud (ppg)
Extra Pull load (lbf)
Wet weight
(lbf)
Total weight
(lbf)2000 19.5 155 94 188000 9.6 10,000 160446 170446
5800 19.5 155 68 394400 9.6 10,000 336595 346595
10100 19.5 155 40 404000 15 10,000 311481 321481
13000 19.5 155 23 299000 16.4 10,000 224136 234136
The red boxes in the above tables indicate the maximum load in each case that the
hoisting system is able to withstand.
Minimum number of lines
Ff=(W*1,6)/(n*E)<=Fmax E*n=> (W*1,6)/(Fmax)
Where: n: number of lines between the crown and the traveling block
E: efficiency of hoisting system
W: maximum hoisting load of 413174.81lbf.
For E=0,874 and n=6 the inequality is satisfied.
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
Time required to pull 90 ft
Max hook power: Ph = Pd * E = 500 hp *0.874 = 437 hp
Max hoisting speed: v = Ph / W = (437 / 413174.81) * 33000 = 34.9 ft/min
Time required: t = s / v = 90 ft / 34.9 ft/min = 2.57 min
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
Appendix
Table 10 Safety margins
EMD (lb/ft3) MarginPore Fracture Depth Pore Fracture8.95 13.71 2100 9.45 13.218.95 13.77 2200 9.45 13.278.95 13.83 2300 9.45 13.338.95 13.90 2400 9.45 13.408.95 13.96 2500 9.45 13.468.95 14.02 2600 9.45 13.528.95 14.08 2700 9.45 13.588.95 14.14 2800 9.45 13.648.95 14.20 2900 9.45 13.708.95 14.25 3000 9.45 13.758.95 14.31 3100 9.45 13.818.95 14.37 3200 9.45 13.878.95 14.43 3300 9.45 13.938.95 14.48 3400 9.45 13.988.95 14.54 3500 9.45 14.048.95 14.59 3600 9.45 14.098.95 14.65 3700 9.45 14.158.95 14.70 3800 9.45 14.208.95 14.75 3900 9.45 14.258.95 14.81 4000 9.45 14.318.95 14.86 4100 9.45 14.368.95 14.91 4200 9.45 14.418.95 14.96 4300 9.45 14.468.95 15.01 4400 9.45 14.518.95 15.06 4500 9.45 14.568.95 15.11 4600 9.45 14.618.95 15.16 4700 9.45 14.668.95 15.21 4800 9.45 14.718.95 15.26 4900 9.45 14.768.95 15.31 5000 9.45 14.818.95 15.35 5100 9.45 14.858.95 15.40 5200 9.45 14.908.95 15.45 5300 9.45 14.958.95 15.49 5400 9.45 14.998.95 15.54 5500 9.45 15.048.95 15.58 5600 9.45 15.088.95 15.63 5700 9.45 15.138.95 15.67 5800 9.45 15.178.95 15.71 5900 9.45 15.218.95 15.76 6000 9.45 15.268.95 15.80 6100 9.45 15.308.95 15.84 6200 9.45 15.348.95 15.88 6300 9.45 15.388.95 15.92 6400 9.45 15.428.95 15.97 6500 9.45 15.478.95 16.01 6600 9.45 15.518.95 16.05 6700 9.45 15.55
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
8.95 16.09 6800 9.45 15.598.95 16.13 6900 9.45 15.638.95 16.16 7000 9.45 15.668.95 16.20 7100 9.45 15.708.95 16.24 7200 9.45 15.748.95 16.28 7300 9.45 15.788.95 16.32 7400 9.45 15.828.95 16.35 7500 9.45 15.858.95 16.39 7600 9.45 15.898.95 16.43 7700 9.45 15.938.95 16.46 7800 9.45 15.968.95 16.50 7900 9.45 16.008.95 16.53 8000 9.45 16.036.96 16.52 8100 7.46 16.027.00 16.45 8200 7.50 15.957.05 16.40 8300 7.55 15.907.08 16.59 8400 7.58 16.097.06 16.60 8500 7.56 16.107.03 16.51 8600 7.53 16.017.29 16.52 8700 7.79 16.027.55 16.53 8800 8.05 16.037.80 16.94 8900 8.30 16.448.26 16.76 9000 8.76 16.268.54 16.76 9100 9.04 16.268.65 16.71 9200 9.15 16.218.85 16.68 9300 9.35 16.18
10.37 16.89 9400 10.87 16.3910.79 16.90 9500 11.29 16.4011.52 16.91 9600 12.02 16.4112.10 16.94 9700 12.60 16.4412.81 16.98 9800 13.31 16.4813.89 17.05 9900 14.39 16.5514.24 17.09 10000 14.74 16.5914.56 17.13 10100 15.06 16.6314.77 17.18 10200 15.27 16.6814.94 17.22 10300 15.44 16.7215.15 17.25 10400 15.65 16.7515.34 17.27 10500 15.84 16.7715.50 17.30 10600 16.00 16.8015.60 17.33 10700 16.10 16.8315.65 17.35 10800 16.15 16.8515.70 17.38 10900 16.20 16.8815.75 17.41 11000 16.25 16.9115.80 17.43 11100 16.30 16.9315.84 17.45 11200 16.34 16.9515.88 17.45 11300 16.38 16.9515.90 17.46 11400 16.40 16.9615.92 17.48 11500 16.42 16.9815.94 17.49 11600 16.44 16.9915.96 17.50 11700 16.46 17.0015.97 17.51 11800 16.47 17.0115.98 17.52 11900 16.48 17.0215.99 17.53 12000 16.49 17.0316.00 17.54 12100 16.50 17.04
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Eastern Macedonia and Thrace Institute of TechnologyMSc in Oil & Gas TechnologyDrilling Engineering
16.00 17.55 12200 16.50 17.0516.00 17.56 12300 16.50 17.0616.01 17.57 12400 16.51 17.0716.01 17.58 12500 16.51 17.0816.02 17.59 12600 16.52 17.0916.02 17.60 12700 16.52 17.1016.03 17.61 12800 16.53 17.1116.03 17.62 12900 16.53 17.1216.04 17.62 13000 16.54 17.12
21