UNIVERSITI TEKNOLOGI MARAFAKULTI KEJURUTERAAN KIMIAGEOLOGY AND DRILLING LABORATORY(CGE 558)NAME: AHMAD FADHIL BIN JAHARISTUDENT NO: 2014812836EXPERIMENT: DRILLING FLUID CONTAMINATION TESTDATE PERFORMED : 19/05/2015SEMESTER: 3PROGRAMME/ CODE: EH243GROUP:

NoTitleAllocated Marks %Marks

1Abstract/ Summary5

2Introduction5

3Aims/ Objectives5

4Theory5

5Apparatus5

6Procedure10

7Result10

8Calculations10

9Discussion20

10Conclusions10

11Recommendations5

12References5

13Appendices5

TOTAL100

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TABLE OF CONTENTS

TitlePage No.

Abstract3

Introduction4

Objectives4

Theory5

Apparatus6

Procedure6

Results7, 8

Calculations9

Discussion10, 11

Conclusion11

Recommendation11

References12

Appendices

ABSTRACTMud contamination tends to happen regularly during drilling operation. It occurs when there are unfamiliar materials enter the mud system and affect significantly to the mud properties, likely, density, viscosity and filtration. The contaminant used to be is gypsum. The main objective for this experiment is to study the effect of contamination of gypsum (CaSO4 2H2O) to the density, plactic viscosity,and yield point of water base mud. It is done by using a mud balance and viscometer. To determine mud density, mud balance is used. Mud is mixed for 3 minutes and is put into mud balance, by then directly read the density value on it. For plastic viscosity and yield point, viscometer is used. Mud is mixed well for 3 minutes, the readings at 600 rpm and 300 rpm are recorded. From the results, it can be said that the presence of gypsum do affect significantly to the density, plastic viscosity and yield point of the mud. Firstly, as the mass of gypsum increases, the density of mud also increases. Secondly, the higher the mass of gypsum, the higher the plastic viscosity. Thirdly, the yield point of mud is influenced by the amount of gypsum used by directly proportional. Hence, clearly show that the density, plastic viscosity and yield point of water base mud can be manipulated by the gypsum and is directly proportional to each other.

1.0 INTRODUCTION Basically, drilling fluid is a well known as a mud system which primary function to transport drill cuttings to the surface and removed from the fluid before it is recirculated back to downhole. In short, the drilling fluid system can be summarized as when there is significant volume of fluid is pumped through the mud pumps from the surface pits, pass through the drillstring and exit at the bit, up the annular space in the wellbore and back to surface for solids removal and maintenance. In consideration, the selection of drilling fluid used acts as a crucial component because it will determine the cost, technical performance and environment impact, normally, drilling fluids familiarly being used are gas base fluid, water base mud and oil base mud. In drilling, it tends to happen likely of many problems arising during the operation. One of them is mud contamination. Mud contamination happens when there are unfamiliar materials enter the mud system and affect significantly to the mud properties, likely, density, viscosity and filtration.When contaminated, drilling fluids can be considered as potential hazard to the sensitive marine ecosystem, and simultaneously water base mud is the most exposed to contamination. As a going concern, the performance and efficiency of drilling fluids are highly dependent on the density and viscosity, it is necessarily will damage the operation once contaminated. For details, mud contamination result from an overtreatment of the mud system with additives or from materials that enter the mud system during drilling. The most common contaminants to water base mud systems are solids, gypsum/ anhydrite, cement/lime, makeup water, soluble bicarbonates and carbonates, soluble sulfides and salt/ salt water flow. As for calcium ions contamination, the sources of calcium ions come from the gypsum, anhydrate, cement, lime, seawater and hard/ brackish makeup water. For this experiment, water base mud is used as the drilling fluid whereby gypsum as the contaminant to be tested.

2.0 OBJECTIVETo study the effect of contamination of gypsum (CaSO4 2H2O) to the density, plactic viscosity,and yield point of water base mud.

3.0 THEORY Generally, gypsum is a sulfate material composed of calcium sulfate dihydrate, with the chemical formula CaSO4.2H2O, and usually forms as an evaporite mineral and as a hydration product of anhydrite. As for the physical properties, gypsum is soluble in water, exhibits retrograde solubility and becoming less soluble at higher temperature. As for details, there are 4 types of water base mud that represses hydration and dispersion of clay which are high pH lime muds, low pH gypsum, seawater and saturated salt water muds. As for this theory, will explain futher on the high pH lime muds and low pH gypusm. On the other hand, gypsum plays a function as a source of calcium and alkalinity in drilling fluids. Secondly, it is also used as an initiative to lime as a source of calcium when the high alkalinity/ pH is not desired in a mud. Gypsum is regularly added to fluids to precipitate high levels of carbonates when additions of lime will raise pH above particular levels. The other benefits of adding gypsum in drilling muds are, gypsum supplies calcium to inhibit hydration of shales and clays and simultaneously treat water and CO2 contamination in water base mud. Instead, when there is excess amount of gypsum in drilling mud, consequently will cause a severe mud contamination. The mud contamination problem is due to the large extent and presence of calcium ions mainly found in the gypsum itself. This is called calcium ions contamination. As mention early, the sources of calcium ions are gypsum, anhydrite, cement, lime, seawater and hard/ brackish makeup water. Calcium ion is a primary contaminant to fresh water base mud systems. Somehow, it tends to replace sodium ions on the clay surface through a base exchange, causing severe changes in mud properties likely rheology and filtration. Someof rheology properties that might affected are mud density, plastic viscosity and yield point. Proper treatment should be conducted to overcome the calcium ions contamination, instead the treatment highly depends on the source of calcium ions. Firstly, if the source of calcium comes from gypsum/ anhydrite it should be treated with sodium carbonate (soda ash). Secondly, if the source is comes from lime/ cement it should be treated with sodium bicarbonate. One of the parameters of properties to be measured is the yield point which is the stress required for the fluid to flow. The other parameter is called plastic viscosity which can be referred to as the resistance of fluid to flow and can be measured using the viscometer.

4.0 APPARATUS Steel cup Viscometer Mud balance Hamilton beach mixer Measuring cylinder Stirrer pH paper Gypsum Water base mud

5.0 PROCEDURE1. 200 ml of water base mud was measured in a beaker.2. The water base mud was tested for its weight, Plactic Viscosity (PV), and Yield Point (YP) by using a viscometer. The value was recorded in a proper table.3. The water base mud was contaminated with 5 grams of Gypsum.4. The sample was stirred for 3 minutes, aged for 15 minutes, and stirred again for 2-3 minutes. The viscosity, yield point, density and pH were determined.5. Another sample of 200 ml of water based mud was prepared in a beaker.6. Step (3) and (4) were repeated using 10, 15, 20 grams of Gypsum.7. The data were recorded and proper graph of density, PV and YP versus amount of Gypsum added were plotted to see the effect of Gypsum contamination to the mud properties.

6.0 RESULTInitial Water Base MudWater based mud + Gypsum

5 g10 g15 g20 g

Mud Weight (ppg)9.4969.7769.8299.91210.329

Density (SG)1.141.171.181.191.24

pH7.57.87.98.28.5

300 (cP) 2127313754

600 (cP)2829355175

Apparent viscosity, a1414.517.525.532.5

Plastic viscosity, p7241421

Yield point, yp17.526293043.5

Graph 7.1 : Density vs Amount of Gypsum

Graph 7.2 : Plastic Viscosity vs Amount of Gypsum

Graph 7.3 : Yield Point vs Amount of Gypsum

7.0 SAMPLE CALCULATIONApparent viscosity, a= 600/ 2 (cP)= 28/ 2= 14 cPPlastic viscosity, p= 600 300 (cP)= 28 21= 7 cPYield point, yp= 300 p 0.5 N/m2 (lb/100 ft2)= 21 7(0.5)= 17.5 cP

8.0 DISCUSSION Basically, the objective of this experiment is to study the effect of contamination of gypsum (CaSO4 2H2O) to density, plastic viscosity and yield point of water-based mud has been achieved. From the results, clearly showed that the density, plastic viscosity and yield point of water base mud can be influenced by the gypsum. Based on the result from Graph 7.1, indicates the relationship between the amount of gypsum and its density. To summarize, the experiment was conducted by using a water base mud mixed together with addition of 5g, 10g, 15g and 20g of gypsum which acts as a contaminant, as to determine the density the experiment was inplemented by using a mud balance. By referring to the basic theory, T = mT/ VT, denotes that the density is directly proportional to the mass. From the results obtained, clearly showed that when the amount of gypsum used were 0g, 5g, 10g, 15g and 20g, the density reading were 9.496 ppg, 9.776 ppg, 9.829 ppg, 9.912 ppg, and 10.329 ppg. The density of the mud weight slightly increase as the gypsum were added regulalry this due to the increase of the weight of the mixtures. The weight does affect significantly to its density. Thus, the result acquired can be approved as it follows identically to the basis. The higher the mass of gypsum, the higher the density. Furthermore, by referring to the Graph 7.2, denotes the relationship between the amount of gypsum and its plastic viscosity (PV). The implementation was done by using a viscometer, relatively the readings were taken at 600 rpm and 300 rpm and result from these two subtraction values eventually will accounted as the PV. From data obtained, as the amount of gypsum used were 0g, 5g, 10g, 15g and 20g, the PV read 7 cP, 2 cP, 4 cP, 14 cP, 21 cP. When viewed in the rough, it can be said that as the gypsum used increase the PV did increase, somehow, human error tend to occur simultaneously and eventually affect the result. If noticed, the read at 0g gypsum gave 7 cP value. This absolutely vary from the actual result and likely it should be less than 2 cP (5g gypsum). Probably, there is no enough time for the mud to mix evenly and cause accumulation to occur afterward because large particles do not break into small particles completely. Proper step, mud should be mixed for at least 5 minutes enhance from before, 3minutes. Second reasons, might cause from the long period of elapsed time, after mud (0g gypsum) is mixed for 3 minutes it should be further tested to the viscometer apparatus promptly. When there is high time elapsed, it will cause the mud to be left for several minutes, somehow will cause the suspended of mud to occur under uncertain temperature that do affect severely. Instead, PV represents the shear rate viscosity encounter at the drill bit. At low PV, denotes that mud is capable to drill rapidly because of low viscosity of mud exiting at the bit, likewise, at high PV, it is caused by a viscous base fluid and by excess colloidal solids. Thus, the higher the mass of gypsum, the higher the plastic viscosity. On the other hand, based on the Graph 7.3, shows the relationship between the amount of gypsum and its yield point (yp). The same methodology was used to find the yp by using a viscometer, yp obtained by reading at 300 rpm 0.5 PV value. As learn before, yp is used to evaluate the ability of a mud to lift cuttings out of annulus, whereby high yp indicates that mud has ability to carry cuttings better than a mud with lower yp. From result, when 0g, 5g, 10g, 15g, 20g were used the yp values were 17.5 cP, 26 cP, 29 cP, 30 cP and 43.5 cP. The yp of the mud slightly increase when there is high amount of gypsum added, yet 20g gypsum is much better than 0g gypsum because it has more capability to carry cuttings, so as it result in higher yp. For more details, yp is described as a resistance of initial flow or the stress required to move the fluid. In theoretically, the value of yp should be increasing after adding a calcium ion (gypsum) and based from the results, it is approved finally. Hence, the higher the mass of gypsum, the higher the yield point.

9.0 CONCLUSION Based on the performed experiment, it can be said that the presence of gypsum do affect significantly to the density, plastic viscosity and yield point of the mud. To conclude, firstly, as the mass of gypsum increases, the density of mud also increases. Secondly, the higher the mass of gypsum, the higher the plastic viscosity. Thirdly, the yield point of mud is influenced by the amount of gypsum used by directly proportional. Hence, clearly show that the density, plastic viscosity and yield point of water base mud can be manipulated by the gypsum and is directly proportional to each other.

10.0 RECOMMENDATION1. The mud should be mixed at least 5 minutes to make sure that it is mixed evenly and make sure that the time elapsed after being mixed should be in exact prospect.2. Make sure that the time taken for each samples of mud is not vary when running the viscometer, because when it is running too longer eventually the mud viscosity will become more high and affect the result.3. After complete the experiment, the contaminated mud (with gypsum) should be disposed into a proper places. Do not tempt to put the mud back into the original water base mud container, it will severely affect the other experiment to be conducted.

11.0 REFERENCES

12.0 APPENDICES