oslc g hp distribution and ohwm stress analysis_rev 08-17-12

Confidential Copyright Schlumberger

OSLC G HP DISTRIBUTION AND OHWM STRESS ANALYSIS

Appendix Z

Document Type

Software Microsoft Word XP

Source File Document3

Other Source File SPC_manual.dot

Author Antonio De Ita Ventura

Author info

Review & approval Marcelo Santamaria

Yuliana Casas Casas

Revision History July 12, 2012 First review

July 21,2012

August 17, 2012 OHWM FEA WITHOUT SAFETY FACTOR

Last saved 17-Aug-12 11:17


Contents

1 OVERVIEW..................................................................................................... 1-1

2 OSLC G HORSE POWER (HP) DISTRIBUTION ........................................... 2-1

2.1 OSLC G ENGINE HORSE POWER AVAILABLE. ................................................................ 2-2

2.2 WINCH PUMP POWER SPECIFICATIONS .......................................................................... 2-3

2.3 WINCH HYDRAULIC MOTOR. .............................................................................................. 2-5

2.4 AUBURN GEARBOX MODEL 10 .......................................................................................... 2-8

2.5 Interaction of Winch pump - Winch Motor Gearbox -Cabledrum. ................................ 2-8

3 OHWM STRESS ANALYSIS ........................................................................ 3-13

4 Conclusion .................................................................................................. 4-24

5 References .................................................................................................. 5-24

Part # OSLC G Page 2-1

Revision # HORSE POWER DISTRIBUTION & OHWM FEA 17-August-2012


1 OVERVIEW

The OSLC G truck is rated to develop a constant Up Hole cable pulling force of 8000 Lbf

without compromise performance and safety of any of the system components. Actual

logging applications demand to do the job at deeper levels therefore more pulling force may

be demanded to the entire systems of the truck.

This document shows how the available engine horse power is distributed through the

systems ending up with the available HP at the cable. With this information we can validate

that the OSLC G can develop a constant Up Hole cable pulling force of 12000 Lbf without

compromising performance and safety of any of the system components.

2 OSLC G HORSE POWER (HP) DISTRIBUTION

The following picture shows the cinematic chain of the systems. It will be used in order to

clearly identify how horse power is used.

Picture 1 OSLC G cinematic chain of systems




2.1 OSLC G ENGINE HORSE POWER AVAILABLE.

The OSLC G is equipped with a RENAULT DXI 11 engine rated to 280 KW@1900 RPM

however It does the logging job at constant speed set at 1300 engine RPM, this speed CAN NOT

be change by means of the SWCT so the engine performance graph has to be studied in order to

find out the available power at such speed.

Picture 2 OSLC G DXI 11 ENGINE POWER CURVE

From the power curve we can see that the engine can deliver up to 245 KW@1300 RPM in a

laboratory conditions. So it is known that in real conditions the efficiency of the combustion

engine can be estimated to about 80% of reported data. Also notice that at such speed the engine

delivers its maximum torque output 1800 Nm.

So the engine in real conditions can deliver up to 196 KW@1300 RPM.

Power is consumed by the following components of the engine:

a) Fan for cooling purposes (3 KW)

b) Air compressor (3KW)

c) Alternator & A/C (2KW)

Therefore the engines crankshaft available output power is around 188 KW@1300 RPM This

power is used to drive a full hydraulic system.




The hydraulic system is a close loop circuit with an efficiency close to 90%. Appling this percent

factor to the crankshaft output power we found that the hydraulic system input power is 169KW

Taking a look to picture 1 we can see that the Generator is rated to 40KW of power so 40 KW

will be taken out from the hydraulic system input power therefore the remaining power is

169KW 40KW = 129 KW

The 129 KW is the power available to produce the Up Hole pulling force on demand.

Converting this 129 KW to Horse Power it results: 173HP

2.2 WINCH PUMP POWER SPECIFICATIONS

The OSLC G is equipped with a SAUER Series 90 100 CC which has the following operation

capabilities:




As shown in the picture the pump delivers a torque of 970 lbf In per each 1000 psi a maximum

displacement (100 cc).

The winch pump rotates at higher speed than the engines crankshaft due to the Power Take-Off

ratio after the trucks gear box. It rotates 1.35 times faster than the engine, so applying this factor

to the engine RPM it results:

Winch pump Speed (WPS) = 1300*1.35 = 1755 RPM

It is possible to find out the power that the pump can handle per every 1000 psi developed. To do

so the following formula is used:

HP = ((Speed)*(Torque))/63000 Equation [1]

HP = ((1755 RPM)* (970 lbf in))/63000= 27

The maximum working pressure already set in the pump for UP Hole is 5000 psi so the maximum

power that the pump can handle is:

Maximum Allowable horse power for winch pump: 5*27 = 135 HP

Notice that the input power can be higher than the one that the Winch pump handles. This power

will be demanded in function of pressure and speed.

The following formulas will be used (section 2.5) to compute the full interaction of the pump,

hydraulic motor, gearbox and cable drum sizes in order to determine the amount of cable tension

developed based on system pressures, flow rates and drum diameter.




We can get the pump output flow in order to understand how this formulas work:

Qe =

Equation [1]

Notice that the divider is only 1 instead of 1000 it is because the units must be consistent in all

calculations.

Qe =

= 168480 cc/min

So the maximum output flow from the pump will be 168480 cc/min@100cc of displacement and

1775 RPM

2.3 WINCH HYDRAULIC MOTOR.

The OSLC G is equipped with a hydraulic motor from SAUER Series 51 80cc/32cc 2 speed

which has the following specifications:




The maximum output power from the hydraulic motor will be at maximum displacement (80cc)

and of course it will be in function of the speed.

From the following formula It is possible to find out the maximum output power that can be used

to create a pull force into the logging cable:

Output power (KW) =

Equation [2]

Where:

Qe: input flow (L/min)

P: Effective hydraulic pressure (Bar)

nt: efficiency

What is known is as follows:

Qe = 168480 cc/min = 168.48 L/min

P: 344.73 bar (5000 psi) 24.13 bar (350 psi) = 320.6 bar

ETm: 0.94

By input the values the result is:

Output power (KW) =

= 84.62 KW

Converting this value to horse power results in:

Outputpower (HP) = 113.47

The following formula is used to calculate the motor output rpm (MS) based on maximum winch

pump flow at maximum displacement.

MS =

Equation [3]




Where:

Vg: Displacement of the motor (cc)

Qe: input flow (cc/rev)

EVm: Volumetric efficiency

What is known is as follows:

MD: 80 cc

Qm from section 2.2 = 168480 cc/min

EVm: 0.94

So by input the values to equation 3 give us:

MS =

= 1969.64 RPM

So the maximum power available for cable tension is going to be 113.47 HP@ maximum

displacement of the winch pump and at maximum displacement of the motor with a pressure

system in the UPHOLE line of 5000 psi.

The following formulas will be used (section 2.5) to compute the full interaction of the pump,

hydraulic motor, gearbox and cable drum sizes in order to determine the amount of cable tension

developed based on system pressures, flow rates and drum diameter.




2.4 AUBURN GEARBOX MODEL 10

The OSLC G is also equipped with an Auburn Gearbox Model 10 coupled to the Sauer Series 51

hydraulic motor as final drive. This gearbox has a ratio of 52.35:1.

The following picture shows its technical information:

This information is used to compute the full interaction of the pump, hydraulic motor, gearbox

and cable drum sizes in order to determine the amount of cable tension developed based on

system pressures, flow rates and drum diameter.

2.5 Interaction of Winch pump - Winch Motor Gearbox -Cabledrum.

Since the Winch pump does not operate at full displacement at all times and the cable drum

diameter varies depending on the amount of cable into the well the final speed and pull force is

changing at every cable layer.

In order to find out the capabilities of the hydraulic system It is studied at its maximum and

minimum capabilities so this allow to come up with graphs that show the performance as the

conditions are changing. The following chart shows the hydraulic system parameters all based in

the formulas listed above.




CHART 1.- Hydraulic system maximum and minimum working parameters .




The following pictures show the expected performance of the hydraulic system under many cases,

all the data was taken from chart 1. Picture 3 shows the cable tension to be developed based on

the drum diameter. Notice that the drum diameter changes as the cable is spooled out or in.

Picture 3 Cable tension based on pressure system and drum diameter

So the OSLC G will work with a cable drum WDR59E that has a core diameter of 24. It is expected to pull 12000 lbf while the cable drum has only 14 layers of cable. Each layer increases

the core diameter by 0.48 times 2 so the diameter of the drum will be:

Drum Diameter= 24 + ((0.48*14)*2)=37.44 in

Looking at picture 3 it shows that to generate a cable tension of 12000 lbf with a cable drum

diameter of 37.44 in the hydraulic system will develop an UP HOLE pressure of 4000 psi or even

4500 psi depending on the distance to log the well at such tension and the speed of the cable.

Notice that as the drum diameter increases the cable tension will be lower if the pressure is

constant.

Picture 5 shows the speeds allowable based on cable diameter and displacement of the hydraulic

pump and hydraulic motor




Picture 4 Maximum cable tension based on drum diameter

Picture 5 Cable speed based on drum diameter




2.6 STRESSES ON 120H CHAIN WITH A REPORTED TENSILE STRENGHT OF 45100 Lbs

The chain drive is a critical part that must be properly calculated in order to minimize the likely

of an unexpected failure while logging. So the following chart shows the expected chain tension

based on cable drum type, depth and cable tension. Keep in mind that the Schlumberger standard

says that a safety factor of 6:1 must be accomplished.

Picture 6 CHAIN TENSION CHART BASED ON DETPH AND CABLE TENSION




The no color zone is for a 6:1 factor, the cream color zone is for a 4:1 safety factor, red color

zone is for a lower safety factor. This zone never can be used.

3 OHWM STRESS ANALYSIS

Since the desired pulling cable force is going to be higher than recommended pulling force a

stress analysis to the OHWM frame is recommended in order to assure no any structural damage

will be associated when pulling to a constant force of 12000 lb f.

The OWHM frame is Aluminum alloy 5083 made. The stress analysis will be done with a safety

factor of 2.5 times the desired working load (pulling force) the weight of the cable drum is also in

account. This factor is most recommended in engineering design but also most standards (like

DNV 2.7-1) recommend it.

The criteria to understand the stress in the OHWM will be the Von Misses Stress and the

maximum principal stress. This criteria is used to predict yielding of materials under any loading condition from results of simple uniaxial tensile tests. The von Mises stress satisfies the

property that two stress states with equal distortion energy have equal von Mises stress.

One main data needed is the Yielding stress of the Material, it is:

y= 190 Mpa.

In order to know when the material will be in the safe range, the maximum allowable working

stress in the results must be no higher than 2/3 of y.

Therefore:

A= (2/3)*190Mpa = 126.6 MPA.

A is the maximum stress that can be in the results of the stress analysis in order to work in a safe mode.




The following picture is a free body of the structure with the loads that are going to be applied to

calculate the stresses generated under such loads. The pulling force will be with an angle related

to the horizontal plane so that force will have 2 components, one component will be in the Y axis

(vertical or pointed up) this component creates a tension stress and the other one will be in the X

axis (horizontal) which creates a shear stress.

The worst case is the shear stress. The material may fail by shear stress before it fails by tension

stress. So the analysis is focused in full shear stress.

3.1 OHWM FEA WITH A SAFETY FACTOR OF 2.5

Picture 7 OHWM FRAME body free with loads with safety factor of 2.5

To analyze the stresses in the OWHM frame the software CREO SIMULATE from Parametric

Technology Corporation (PTC) was used. The results are as shown:




Picture 8 OHWM FEA Results 1: Maximum principal stress

From picture 7 it is noted that most of the frame will be in compression this is because of the

cable drums weight. The highest stress is at the red spots which has a value of 113.8 MPa this

stress is acceptable due to it does not goes beyond the allowable working stress for the material

(A= 126.6 MPa).

A closer look at the locations where the highest stress was found is presented in the following

pictures.




Picture 9 OHWM FEA results 2. Stresses at pillow block mounting holes of frame.

As expected the highest stress area is located at the mounting holes for the pillow block. It is

because all the loads are transmitted there by means of the bolts. Picture 8 shows the way the

stress are distributed in the top plate of the OHWM.

As mentioned above the maximum principal stress is shown in red and has a value of 113.8 MPa

which is acceptable.

Picture 9 is a close look to the turnbuckles pin mounting plate. These plates will be working

under high stress but beyond the allowable stress.

Picture 10 OHWM FEA RESULTS 3. Stresses at turnbuckle reaction force




Picture 11 OHWM FEA RESULTS 4. OHWM stresses at frame mounting holes.

The holes to secure the OHWM to the chassis truck are under high stress also. However the

maxim stress is 113.9 MPa.

This stress is a contact stress which is not critical for this application.

The maximum deflection has to be found out to check for any issue that may be present. The

following picture shows a maximum displacement of 0.76 mm. This displacement is not critical.

Note that the picture has a zoom X of 279 times that is why the frame looks like deformed kind

bad.

Picture 12 OHWM FEA RESULTS 5. OHWM deflection.




3.2 OHWM FEA WITH NO SAFETY FACTOR

In order to figure out the expected stresses while doing a logging job the OWHM is analyzed

under loads without a safety factor. Remind that the safety factor is used to guarantee no any

issues will come up if a unexpected event of overload happens and to countermeasure variations

of the fabrication method.

The analysis with the safety factor does not replace any non destructive test procedure of the

welds. The following picture shows the stresses to be expected in the OHWM without safety

factor

Picture 13 OHWM FRAME body free with loads without safety factor




Picture 14 OHWM FEA ANALISYS RESULTS WITHOUT SAFETY FACTOR: PRINCIPAL MAXIMUM STRESSES

As expected the maximum principal stresses to be present under actual load conditions is 51.6

MPa which is a value low compared against the allowable stress for the material of the OHWM.




Picture 15 OHWM FEA ANALISYS RESULTS WITHOUT SAFETY FACTOR: PRINCIPAL MAXIMUM STRESSES @ PILLOW BLOCK MOUNTIG HOLES




Picture 16 OHWM FEA ANALISYS RESULTS WITHOUT SAFETY FACTOR: PRINCIPAL MAXIMUM STRESSES @ TURNBUCKLE SUPPORTING PLATES




The following picture is in regards of the maximum deflection expected:

Picture 17 OHWM FEA ANALISYS RESULTS WITHOUT SAFETY FACTOR:MAXIMUM DEFLECTION

NOTE: The picture is showing the deflection scaled 744 times up.




4 Conclusion

The OSLC G can develop a constant pulling force (UP Hole) of 12 000 lbs without sacrifice

performance of any of the systems however a rigorous maintenance, tests and inspections prior to

job must be done in order to keep all the hardware in good condition.

Safety rules must be followed as per working with high pressure standards. It is because the

working pressure while pulling 12000 lbf is going to be from 3500 psi to 4000 psi.

.

On the other hand all the results in regards of stresses in the OHWM are considering a good full

penetration of all the welds, so Non Destructive Test is recommended in order to guarantee good

performance of the frame.

From the chain analysis it is highly recommended to replace the chain after each job if the cable

tension was equal or more to 12000 lbs. It is because the working safety factor is going to be 4.

Replacing the chain will not allow to go below such safety factor.

5 References

A) Dave Richardson, PULL ON LINE, excel file. He was the Manager for the Gulf Coast Service Center for about 5 years before get retired. He did coordinate and design the

CAPSTAN project. He deployed the first CAPSTAN system to the NGC geo market.

B) OSLC_G_MM_Vol2_V2_1__4368929_01 Manual

C) BENDIX TU FLO 550 Air compressor datasheet.

D) Sauer series 90 pump datasheet

E) Sauer series 51 bent axis motor datasheet

oslc g hp distribution and ohwm stress analysis_rev 08-17-12

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