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UNIVERSITI TEKNOLOGI MARA FAKULTI KEJURUTERAAN KIMIA OIL AND GAS ENGINEERING LABORATORY II (CGE 557) No Title Allocated Marks % Marks 1 Abstract/summary 5 2 Introduction 5 3 Aims/objectives 5 4 Theory 5 5 Apparatus 5 6 Procedure 10 7 Result 10 8 Calculations 10 9 Discussion 20 10 Conclusion 10 11 Recommendations 5 12 References 5 13 Appendices 5 Total 100 NAME & : Afuza Husna STUDENT ID (2010) Rozalin Danis (2010467864) Amirul Hakim Bin Mat Azahar (2010409492) Muhammad Ilham Bin Juanda (2010485804) Mohammad Zhafry Bin Samsuddin (2010873498) EXPERIMENT : 1 DATE PERFORMED : 23 March 2012 SEMESTER : 4

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Page 1: -Lab Experiment 1 Repaired)

UNIVERSITI TEKNOLOGI MARA

FAKULTI KEJURUTERAAN KIMIA

OIL AND GAS ENGINEERING LABORATORY II

(CGE 557)

No Title Allocated Marks % Marks

1 Abstract/summary 5

2 Introduction 53 Aims/objectives 5

4 Theory 5

5 Apparatus 5

6 Procedure 107 Result 10

8 Calculations 10

9 Discussion 20

10 Conclusion 1011 Recommendations 5

12 References 5

13 Appendices 5

Total 100

Remarks:

Checked by:

NAME & : Afuza HusnaSTUDENT ID (2010)

Rozalin Danis (2010467864) Amirul Hakim Bin Mat Azahar

(2010409492) Muhammad Ilham Bin Juanda (2010485804) Mohammad Zhafry Bin Samsuddin (2010873498)

EXPERIMENT : 1DATE PERFORMED : 23 March 2012SEMESTER : 4PROGRAMME/CODE : EH 223GROUP : EH 223 4A

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Abstract/summary

An artificial neural networks (ANN) model has been developed to provide accurate predictions of mud density as a function of mud type, pressure and temperature. Available experimental measurements of water-base and oil-base drilling fluids at pressures ranging from 0 to 1400 psi and temperatures up to 400 °F were used to develop and test the ANN model. With the knowledge of the drilling mud type (water-base, or oil-base) and its density at standard conditions (0 psi and 70 °F) the developed model provides predictions of the density at any temperature and pressure (within the ranges studied) with an average absolute percent error of 0.367, a root mean squared error of 0.0056 and a correlation coefficient of 0.9998.

Introduction

The density of a drilling fluid is normally determined at standard conditions of 0 psi and 70

°F. As the drilling operation progresses, the drilling fluid will be subjected to increasing

pressure and temperature. While the higher pressure increases the drilling fluid density, the

increased temperature results in density reduction. Proper planning and execution of drilling

operations, particularly for HPHT wells, requires complete and accurate knowledge of the

behavior of the drilling fluid density as the pressure and temperature change during the

drilling operation. Such information can accurately be obtained only through actual

measurements of the drilling fluid density at desired pressures and temperatures. This,

however, requires special equipment along with difficult and time-consuming procedures.

Prediction of the drilling mud density at various pressures and temperatures is, therefore, very

useful for mud and drilling engineers in planning drilling operations.

McMordie et al1 studied the effect of temperature and pressure on the density of water-base

and oil-base drilling fluids. They presented experimental measurements of densities in the

temperature range of 70 °F to 400 °F and pressure range of 0 - 14000 psi and concluded that

the change in mud density with pressure and temperature is independent of the initial mud

density (at 70 °F and 0 psi). They also concluded that for equal densities at surface

conditions, oil-base drilling fluids become denser than water-base drilling fluids at high

temperatures and pressures. Okoye et al2 used the data of McMordie et al and developed

various correlations of water-base mud density as a function of temperature for various

values of surface mud density. These correlations, however, ignored the effect of pressure on

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mud density and are limited to water-base drilling fluids of specific surface density and to the

range of temperatures and pressures covered by the experimental measurements.

Away from empirical correlations and their inherent limitations, artificial neural networks

(ANN) models have been proven in recent years to be very effective means of solving

difficult problems in the oil industry. This paper presents an ANN model that provides, with

great accuracy, predictions of water-base and oil-base drilling fluids density. Identifying the

type of drilling fluid (water-base, or oil-base) and the density at surface conditions, the

developed model predicts the density at any temperature and pressure.

Objectives

To determine the density of different sample of drilling mud

Theory

Apparatus

Mud samples (oil and water base mud), Fan Mud Balance, hydrometer and measuring cylinder.

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PROCEDURE

Procedures

Fan mud balance;

Calibration

1. Filled the cup with water.

2. Placed the lid on the cup and seat it firmly. Be sure some mud runs out of the hole in

the cap.

3. With the hole in the cap covered with a finger, all the water from the outside of the

cup and arm are washed or wiped.

4. Set the knife edge into the fulcrum and move the rider along the graduated arm until

the cup and arm are balanced.

5. Read the density of the mud at the left-hand edge of the sliding weight.

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6. Report the results to the nearest scale division in lb./gal.; lb./cu. ft.; S.G. (specific

gravity); or psi/1000 ft. of depth.

7. Wash the mud from the cup immediately after each use. It is absolutely essential that

all parts of the mud balance be kept clean if accurate results are to be obtained.

Test procedure

1. The lid from the mud cup is removed and filled with the mud sample.

2. Placed the lid on the cup and seat it firmly. Be sure some mud runs out of the hole in

the cap.

3. The mud from the outside of the mud cup is washed or wiped.

4. Placed the balance arm on the base, with the knife-edge resting on the fulcrum.

5. Moved the rider until the graduated arm is level, as indicated by the level vial on the

beam.

6. At the left-hand edge of the rider, read the density on either side of the lever in all

desired units without disturbing the rider.

7. Noted down the mud temperature corresponding to density.

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Hydrometer;

1. Used the same mud sample as used in the mud balance experiment.

2. Filled the hydrometer cylinder (graduated cylinder) with the drilling mud to within 1

to 2 inches of the top by pouring the sample slowly down the side of the cylinder.

3. Chose the correct hydrometer for measuring specific gravity, SG of the drilling fluid.

4. Inspected the hydrometer to ensure that it is clean and dry.

5. Placed the hydrometer carefully in the cylinder, allowing it to gently settle to the

proper measurement level.

6. Spin the hydrometer and record the reading at which the hydrometer rests.

7. Record the reading and compared with the reading obtained from mud balance

experiment.

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Result

Mud Weight ppg lb/ft3 psi/1000ft SG

Oil-based mud 11.6 87.0 602.0 1.098Water-based mud 10.6 79.5 551.0 1.272

Mud density measurement using mud balance

Mud density measurement using hydrometer

Mud WeightSpecific Gravity (SG)

Average Density (SG)1st trial 2nd trial 3rd trial

Oil-based mud 1.042 1.042 1.038 1.0407Water-based mud 1.308 1.310 1.313 1.3103

Calculation

Oil-based mud

Using mud balance,

Mud weight = 11.60 ppg

1 ppg = 7.48 lb/ft3

87.0lb

ft3×

1 ppg

7.48lb

ft3

=11 .63 ppg

1 ppg = 0.12 SG

1.098SG×1 ppg

0.12SG=9.15 ppg

1 ppg = 0.052 psi/ft

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602

psi1000 ft

×1 ppg

0.052psift

=11 .57 ppg

Using hydrometer,

1 ppg = 0.12 SG

1.0407 SG×1 ppg

0.12 SG=8 .67 ppg

Water-based mud

Using mud balance,

Mud weight = 10.60 ppg

1 ppg = 7.48 lb/ft3

79.5lb

ft3×

1 ppg

7.48lb

ft3

=10 .63 ppg

1 ppg = 0.12 SG

1.272SG×1 ppg

0.12SG=10 .60 ppg

1 ppg = 0.052 psi/ft

551psi

1000 ft×

1 ppg

0.052psift

=10 .59 ppg

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Using hydrometer,

1 ppg = 0.12 SG

1.3103SG×1 ppg

0.12SG=10 .91 ppg

DISCUSSION

For the determination of density of mud using the mud balance, we firstly made a calibration

of the mud balance by using a fresh water to check for error of the mud balance. We got

exactly 1.00 SG for the water. After we done with the calibration, the mud balance is

perfectly fine and ready to go for the mud density determination.

The mud balance can give us a direct measurement of of mud density in four unit that are ppg

(lbm /gal), lb./ft3, psi/1000 ft., specific Gravity (SG) as shown in table in the results above.

While the hydrometer only give the reading of density by SG.

Water base mud weight measured using hydrometer is 1.3103 SG. The result follows

expected values declared in M-I SWACO (2001) which the standard mud weight of water

based mud usually used in drilling operation is between 1.054 to 1.618 SG.

While the oil base mud weight measured using mud balance and hydrometer are

1.0407 SG respectively. These results were also complied with expected value published by

M-I SWACO (2001). In which a standard mud weight of oil based mud is normally between

1.019 to 1.917 SG.

There is difference between reading taken using mud balance and hydrometer. For oil

based mud, the discrepancy is 0.0573 SG while for water based mud is 0.0383 SG. Mud

balance is a more accurate tool to acquire specific gravity of mud. It is because hydrometer is

actually unreliable in drilling fluid because of gelation (Schlumberger oilfield glossary,

2011).

The gelation describe the process of formation jelly like substances within the drilling

fluids that having high property of suspending solid material. Most of mud commonly used

comes with this particular behaviour, due to requirement of the drilling process that want any

excessive material such as cuttings that been encounter via the drilling process can be

suspended by the drilling fluid and regulated through the drilling system so that the cuttings

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can removed from the drilling process. Thus such floating additive behaviour will creates

artificial lifting for the hydrometer to suspend with the drilling fluid and affects the reading

obtained. In some other cases the hydrometer usage is an appropriate as the gelation process

occurs in mud will create difficulty on estimating the density of the particular drilling fluid.

Error will often encounter if the gelation exist whereby the fluid density cant determined

properly.

We always have different advantages and disadvantages when we used varies of method. If

we use the mud balance, we will have a better and more accurate reading compare with

hydrometer. For the first reason is the trapped air inside the mud cup can be freed as the mud

cup lid allows the air to escape from the mud cup as closed. This therefore gives us a correct

measurement of the density of the mud. On the other hand, we can’t expel the trapped air

when we use the hydrometer. Thus, less accurate data will be obtained through this method.

Moreover, measurement using hydrometer involves indeterminate errors cause a measuring

process to give different values of densities when that measurement is repeated many times.

The effect that indeterminate errors have on results can be somewhat reduced by taking

repeated measurements then calculating their average. The average is generally considered to

be a "better" representation of the "true value" than any single measurement, because errors

of positive and negative sign tend to compensate each other in the averaging process. In a

comparison, mud balance will a definite reading as we first do a careful calibration of that

apparatus. There is no different values of densities and indeterminate errors.

Hydrometer is not very suitable to be used for measuring mud density because it is fragile.

Most importantly, before measuring using hydrometer, the most suitable hydrometer scale

must be first determined. The reason is hydrometer has varies scale; and only one hydrometer

will suit for certain type of fluid density. Therefore, this trials and error method is also

complicated and time consuming. As compared to mud balance, it provides a simple,

practical method for the accurate determination of fluid density. Most importantly, it contains

no easily broken parts like hydrometer. The item's durable construction makes it is ideal for

field use.

After determined both densities of the mud, then only we can decide if the mud is suitable to

be used during the drilling operation. From our research, both sample of mud are suitable to

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use during the beginning of the drilling operation. This is because, the density of both water-

based mud and oil-based mud are low. It is enough to maintain the pressure inside the

wellbore to withstand the formation pressure. It is important because it prevents the borehole

from collapsing and prevents the influx of formation fluids.

We can’t use these muds when we reached a very high depth of borehole. This may cause

kicks or blowout as it can’t maintain the formation pressure. This is because the mud pressure

will be less than the formation pressure as the formation pressure increases when the depth

increases. This is also known as underbalance. Thus, we need to use higher density of mud to

overpower the formation pressure. The pressure exerted by the mud must be greater than the

formation pressure. This is called overbalance which is crucially needed to be kept through

the drilling operation.

Even though, the mud pressure can’t be too high. Otherwise, lost circulation will happen.

This incident occurs when the mud pressure is too high and overwhelming the formation

pressure. This will lead to the reduction of penetration rates, breaking down of formation, and

causing stuck pipe.

In another word, we must stay alert and check the formation pressure frequently so that we

know when we need to change the mud to be pumped inside the borehole.

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Conclusion

From the experiment we get the density of the oil and water base mud by using mud balance

and hydrometer. As we measured we get 10.60ppg of water base density while for oil base

mud the density is 11.60ppg. The value of the mud weight is varies with different fluid as

every fluid have it own properties. As a conclusion the density of the water based is higher

than the oil base mud for both instrumental used. By knowing the density of the mud, we can

avoid some problem during drilling prosesses for example prevent the substance to float after

the mixture or avoid lost circulation. Beside that we can predict how much mud that we need

to carry out the cutting rock. Therefore the experiment is sucessful.

Recommendation

There are some recommendation should be taken to give the better results. There is also some

precaution that should be taken to prevent error in this experiment. For example;

1. Wipe the cup cleanly to have the accurate specific gravity.

2. The cup must be clean and dried to have the accurate specific gravity.

3. The water based mud should be stirred by using the mixer to prevent the precipitation

inside it.

4. Use suitable size of measuring cylinder to make sure that the hydrometer will have the

ability to float and sink inside the mud

5. Take the average reading as the result to avoid error.

6. Pressurized mud balance is recommended in order to get the best measurement of mud

density.

7. The pressurized mud balance looks like the convention one, but it has a pressurized

sample cup. When you press mud sample in the cup, any gas in fluid phase is compressed

to very small volume so the mud weight measurement is more accurate.

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References

1. Drilling Engineering Laboratory Manual; Oil and Gas Engineering Laboratory 2

(CGE 557)

2. Drilling Engineering; J.J. Azar, G. Robello Samuel; PennWell Corporation.

3. http://en.wikipedia.org/wiki/Drilling_fluid

4. http://www.drilling-mud.org/mud-weight-or-mud-density/

5. http://www.glossary.oilfield.slb.com/Display.cfm?Term=mud%20weight

6. http://en.wikipedia.org/wiki/Hydrometer

7. http://www.glossary.oilfield.slb.com/Display.cfm?Term=mud%20balance

8. http://en.wikipedia.org/wiki/Mud_balance

Appendices

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Expected result

Mud balance;

Type

Mud weight

SG psi/1000 ppg

Oil base

Water base

Hydrometer;

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Type SG Density mud

Oil base

Water base