Development of Environmental Friendly Drilling Fluid Additives

SPE-xxxx-MS Development of Environmental Friendly Drilling Fluid Additives.

Authors; Kholood Hamad, Al-Anoud Al-Aid, and Ghanima AlDhufairi, The Australian College of Kuwait.

Copyright 2018, Society of Petroleum Engineers This paper was prepared for presentation at the SPE International Conference on Health, Safety, Security, Environment, and Social Responsibility held in Abu Dhabi, UAE,16-18 April 2018.

This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s).

Contents of the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.

Abstract Drilling fluid is an essential part of the drilling operation, it is more like the blood in our veins, it represents (15-20%) of the total cost of well drilling, it is very difficult to get standard drilling fluid with standard additives, since each well needs a specific drilling fluid, depending on well condition such as; pressure, formation type, size of the hole etc, with the increase in environmental regulations and laws against the deposition of drilling fluids specially oil based mud, led to the need of drilling companies to create an outstanding drilling mud with a little or no odorous content, which is basically a biodegradable and environmentally friendly drilling fluid with organic additives that manipulate the rheological properties of the mud, and demonstrate no health hazard behavior on the workers in the oilfield as well as the environment surrounding the well.

This study emphasis on the use of bio degradable organic waste such as peelings, as an additives for the drilling fluid, an intensive experimental evaluation of bio degradable environmentally friendly additives were conducted in this paper to examine their feasibility in water based mud, these additives were prepared in house, include Avocado peelings, A mix of fish crab shrimp peelings and scales, and the last additive was a mixture of onion and eggplant peelings, these additives were evaluated at four different concentrations, measuring different properties of the mud, Rheological properties such as; yield point, plastic viscosity and gel strength, filtration loss using low pressure API filter press, and mud cake thickness neglecting the quality of the mud cake, focusing only on the thickness of the mud cake.

The results showed some encouraging potential drilling fluid additive for Avocado peelings 0.714g concentration, which decreased the fluid loss up to 42.2% and gave optimum rheology of yield point and gel strength and the fluid loss can be adjusted by adding bridging materials such as calcium carbonate, and a minor effect on the plastic viscosity which increased due to the solid content added to the mud, Avocado peelings can be LCM which is lost circulation material whereas other additives such as Eggplant and onion peelings decreased the PH dramatically which can be used as alkalinity control agent same as Citric acid which is an organic acid used nowadays to reduce the PH of drilling fluids.

These additives that are demonstrated in this paper showed some promising results to replace toxic chemical additives to reduce the pollution of the formation, and the harmful deposition of the mud, also it is cost effective, it will cost maybe 6 times less than the chemical additives.

Background Drilling fluid also called drilling mud, it is used to assist the drilling of boreholes into the formation

2

below the earth surface, its often used to drill for crude oil and natural gas extraction, it can also be used to drill for water exploration, different types of additives like chemicals and polymers are added to the drilling mud to meet different functional requirements, and manipulate the rheological properties, the PH, Filtration loss and mud cake thickness, also the density plays a major role and it differs and depends on the formation type and density, nowadays the selection of drilling fluid became more complex due to the EPA laws and legislation that resulted in the prevention of using pollutant materials such as chemical additives and polymers that has harmful effect on the formation and might damage the aquifer below the surface, the continuous drilling with harmful drilling mud led to serious threat on the environment, several products that are found on the drilling rig such as; brines, oil based mud, solvents and cleaning agents are very irritating and hazardous to body tissues of the human beings, it reduce fertility and increase mortality rates, it has a harmful effect also on the environment, it is very important to replace these toxic additives with a truly non toxic additives, nowadays people are now paying more attention to the environment than before, and the selection of the drilling fluid now depends on the technical performance, cost, and the environmental effect of it, due to the environmental agencies, material that has been used in the past are no longer acceptable to use it, materials are being re evaluated and re considered before mixing it with the drilling fluid to meet the allowable or acceptable environmental regulations and safety rules. this is known as environmentally drilling fluid systems, which contains non toxic degradable additives, but mud companies don’t want to create an environmentally drilling fluid additive, because they will lose a lot of money when they replace chemical additives with organic additives, Imagine if the price of organic additive is 20$ per sack, the chemical additive is 120$ per sack or more, so if they replaced it with organic additives, they will face difficulties getting more money from governmental industries such as Kuwait Oil Company known as KOC. Since the beginning of the oil and gas industrial era, water was used as a drilling fluid and the resultant observations were noted back in the ancient Egyptian and Chinese cultures, then they used water mixed with natural clays, a comparison between these two on their ability to clean the hole, showed a clear higher results for water with natural clays mud, changes started to occur in 1961 when the API committee was established to set numerous standards, specifications and recommended practices, mud systems were either chemically thinned water based mud or OBM which is oil based mud(diesel), several events occurred that effected the mud industry such as the event that took place in Santa Barbra oil spill resulting in huge rise in Environmental protection awareness, during 1986 and 1990 research and development department results were slow due to the decline in the drilling industry(1961 – 1985) , however due to the critical examination of the EPA, efforts were made to replace OBM(diesel, mineral oil) fluids to SBM synthetic base fluids since then the recovery began but in a slower wave, which contributed in the increase of different studies to use organic waste food scrapes as a drilling fluid additives to manipulate different rheological properties considering cost and availability, nowadays industries use specific organic waste such as; Cornstarch as LCM (lost circulation material).

Materials and Methods This section contains detailed information about the preparation process of the waste material and the preparing procedure of the reference water-based mud.

Preparation of Waste material The first step was to select a random organic waste additive based on logical reason, those wastes were avocado peelings and seeds, fish, crab and shrimp peelings and finally eggplant and onion peelings combined as one additive. In addition, an extra waste was selected like oxidized corn, coconut shell, and mangosteen but was eliminated later after finding that the FCS (fish, crab and shrimps peelings) may serve as LCM as well as the coconut shell. Moreover, the oxidized corn eliminated because it contains starch like the EO (eggplant and onion peelings). While the mangosteen was eliminated because it may not work because it’s considered as acidic. Finally, the selection of the avocado was inspired by the pipe freeing agents as it contains oil and it may increase the viscosity.

SPE-xxxx-MS

3

the second step after the waste selection was getting a sufficient amount of the was and start to dry it; the avocado and EO peelings were chopped into small pieces also the seeds of the avocado were grinded ( Figure 1) and both samples left in an open place exposed to the air for one week. Furthermore, the FCS peelings ( Figure 1) exposed to a 180 F oven flames for about 20 minutes to absorb any moisture then left on an open place as the rest of the samples but for a longer period that reached 12 days. Once dried, the samples were grinded and crushed to a fine powder.( Figure 2)

Figure 1 Organic Waste Additives Preparation

Figure 2 Environmentally Friendly Drilling Additives

Water Based Mud preparation the reference mud sample was prepared using 5% bentonite in 500 ml scale. Also, the reference sample was prepared using 25 gram of bentonite and 475 ml of tap water without any addition of chemical additives. Additionally, the properties of the reference WBM sample is shown in table 1.

Table 1 Reference Mud Properties

Gel10s (lb/100 ft2 )

Gel 10m (lb/100 ft2 )

Yield Point (lb/100 ft2 )

Plastic Viscosity (cP)

Fluid Loss (ml/30 min)

4

13

16

7

15.4

Mud Cake Thickness (inches) 0.0822

pH

9.8

Laboratory Measurement In order to investigate the effect of the different environmental friendly additives on the WBM rheological properties, various equipment was used. First, to evaluate the gel strength at 10 s-m, plastic viscosity (PV)as well as the yield point (YP)a rotary Viscometer was used. While a mud balance was utilized to measure the mud density. Furthermore, to examine the ph of the mud we used a PH-meter.

Finally, to evaluate the filtration characteristics of the mud including the filtration rate ml/30 as well as the filtration thickness a standard API filter press at 100 psi was exploited.

Testing Matrix

4

Diverse concentrations of the environmental Organic mud additives fluctuating between 0.71gm to 7.1 were used. Table 2 represents the dissimilar combinations using diverse additives at different concentrations with the acronym of each additive.

Table 2 Testing Matrix

Blend # RP 1 2 3 4 5 6 7 8 9 10 11 12

Material used Reference Point Avocado Avocado Avocado Avocado Fish, Crab, and shrimp Fish, Crab, and shrimp Fish, Crab,and shrimp Fish, Crab, and shrimp Eggplant and Onion Eggplant and Onion Eggplant and Onion Eggplant and Onion

Acronym RP A A A A FCS FCS FCS FCS EO EO EO EO

Concentration (gm/ml) 0 0.71 1.428 3.56 7.1 0.71 1.428 3.56 7.1 0.71 1.428 3.56 7.1

Presentation of Data and Result Under this section the results of our conducted experiments will be shown; the effect of each concentration of the environmental additive will be discussed.

Table 3 represents a summary presentation of the result of different environmentally friendly additives that have been used in 5% bentonite WBM with various concentration. Furthermore, the rheological properties each additive will be discussed in details to explain the behavior of the gel strength at 10 seconds and 10 minutes as well as the PV and YP asses. In addition, the filtration properties including the fluid loss and the filter cake thickness of each additive will be explained. Followed by, the effect of organic waste on the PH at different concentration. Finally, a summary of comparison between all the additives will be discussed.

Table 3 Summary Various Environmental Friendly Additives Result

Blend Bentonite WBM 5% Bentonite + 0.71A 5% Bentonite + 1.428A 5%Bentonite + 3.56A 5 % Bentonite + 7.1A

PV (cp) 7 10 10 11 10

yp (lb/100ft2) 16 26 28 29 32

gel 10 s 4 13 15 15 15

gel 10 min 13 16 19 19 22

pH 9.8 9.97 9.74 8.87 8.04

fluid loss 30 min(ml) 15.4 6.5 6.5 6.5 3.9

mud cake (in) 0.0822 0.0692 0.0692 0.0692 0.0692

5%Bentonite + 0.71FCS 5%Bentonite +1.428FCS 5% Bentonite + 3.56FCS 5%Bentonite + 7.1FCS

9 10 11 11

26 31 32 34

15 15 13 17

18 18 18 23

9.67 9.56 9.42 9.22

10 10 9 5.8

0.0589 0.0589 0.0515 0.0484

5%Bentonite + 0.71EO 5%Bentonite + 1.428EO 5% Bentonite + 3.56EO 5%Bentonite + 7.1EO

6 8 10 12

8 9 10 11

5 8 14 14

13 14 19 21

9.44 9.2 8.61 7.7

10.1 6 5.5 5

0.059 0.0543 0.0444 0.0433

Rheological properties of bentonite drilling fluids added with Avocado The result reveals that the 10 (s) gel strength approximately increased 3 times more than the RP in the first concentration of 0.71A, while at the rest of the concentration starting from 1.428A it increased 4 times more than the RP and remained constant.

The 10 (m) gel strength increased by 23% at 0.71A comparing with RP; also amplified by 46.2% at 1.428A and percentage remained constant also at the 3rd concentration 3.56A. finally, the percentage

SPE-xxxx-MS

5

reached its maximum value at the last concentration 7.1A by 69% than the RP. The addition of this additive significantly improved the gel strength and the ability of the mud to suspend the cuttings under the static condition it’s also at the acceptable range at high concentration.

Sufficient gel strength will suspend drill cuttings and weighting materials during connections and other static conditions. Gel strengths directly affect surge and swabbing pressures when making connections, tripping pipe or running casing. They also affect the pressure required to “break circulation� and the ease of releasing entrained gas or air. Gels are determined using the same direct indicating rotational viscometer as is used for viscosity an indication if the fluid is continuing to gel with longer periods of time (called progressive gels) or if it has reached a relatively constant value (called flat gels).What is very important to mention that is the gel strength is increasing with A concentration gradually; the high gel strength values are not sought as this requires high pumping pressure once drilling resumed after a period of shutdown. ( Figure 3 ) below shows the comparison between the gel strength of different concentration versus the reference point.

Gel strength 25

22 19

20 16 15

13

19

15

15

15

13

10 4

5 0

Bentonite WBM 5% Bentonite + 5% Bentonite + 0.71A 1.428A gel strength 10 s

5%Bentonite + 3.56A

5 % Bentonite + 7.1A

gel strength 10 min

Figure 3 Gel Strength of A Additive

The rheological profile of avocado shows dial readings with values increasing progressively from 100 rpm dial speed to 600. ( Figure 4 ) shows consistency curves for all A concentrations. All these curves are in a good agreement with the Bingham plastic model, and it is observed that the shear stress increased with the concentration of Avocado at a given shear rate. It seems that the PV persisted constantly after the initial concentration of 0.71A until 7.1A and the change at 3.56A can be considered negligible due to human error.( Figure 5 ) 60

Dial reading

50 40 30 20 10 0 0

100

200

300

400

500

Dial spead RPM 0.71A

1.428A

3.56A

Figure 4 Dial Reading of A Additive

7.1A

RP

600

6

PV (cp) 12

11 10

10

10

10 8

7

6 4 2 0 pv (cp)

Bentonite WBM

5% Bentonite + 5% Bentonite + 5%Bentonite + 5 % Bentonite + 0.71A 1.428A 3.56A 7.1A Figure 5 PV of A Additive

This is particularly good as the drilling mud with higher PV increases the ECD, surge, and swab pressure and also reduce ROP with chances of differential sticking. ( Figure 6 ) indicated that the YP increased gradually as the concentration of A increased in the mud.the range is good but at higher concentration is acceptable. it's as known fact the high yield point fluid has more significance as it indicated better cutting carrying capacity. But if it very high at will require a high pressure to break the gel and it may fracture the formation.

YP (IB/100FT2) 35

32

30

26

29

28

25 20

16

15

10 5 0 Bentonite WBM 5% Bentonite + 5% Bentonite + 0.71A 1.428A yp (lb/100ft2)

5%Bentonite + 3.56A

5 % Bentonite + 7.1A

Figure 6 YP of A Additive

Filtration properties of bentonite drilling fluids added with Avocado Filtration is a vital phenomenon seen in the wellbore due to pressure exerted by the hydrostatic column of the drilling fluid. Due to the pressure differential, a mud cake with very low permeability is formed on the walls of the borehole which performances as a barrier between the formation and the drilled bore. The volume of filtrate loss to the formation is also critical as a drilling fluid with greater filtrate loss parade higher density due to a reduction in the water content of the fluid. moreover, this creates a zone of damage near the wellbore region and is one of the factors considered for formation damage.

The ( Figure 7 ) below shows the trend of the filtrate loss of the drilling mud formulated using the Avocado. The filtration property displays a decrease in the filtrate loss to a 57.8% at 0.71A, 1.428A, and 3.56A comparing with the reference point and stayed constant; until decreased to a maximum of

SPE-xxxx-MS

7

74.7% as the concentration of avocado increased to 7.1A in the drilling fluid. This ensures that a firm filter cake is formed and a lesser amount of filtrate invades the formation which is an important property of a drilling mud, the filter cake stayed constant at all the concentration on Avocado which is shown in ( Figure 8 ).

Fluid loss in ml 18 16

15.4

14 12 10 8

6.5

6.5

6.5

6

3.9

4 2 0 Bentonite WBM 5% Bentonite + 5% Bentonite + 0.71A 1.428A

5%Bentonite + 3.56A

5 % Bentonite + 7.1A

fluid loss 30 min(ml) Figure 7 Filtration loss of A Additive

0.085

0.0822

mud cake in inch

0.08

0.075

0.07

0.0692

0.0692

0.0692

0.0692

5%Bentonite + 3.56A

5 % Bentonite + 7.1A

0.065

0.06 Bentonite WBM 5% Bentonite + 5% Bentonite + 0.71A 1.428A mud cake (in)

Figure 8 Thickness of Mud Cake of A Additive

The properties of the mud after adding FCS additive: The results in the table 3 above were acquired using the equipment mentioned in the methodology.

The table below simplifies the comparison between a diverse blend of concentration for the FCS as well as the reference point.

Rheological properties of bentonite drilling fluids added with FCS The gel strength of this environmental additive discloses from the ( Figure 9 ) reveals that the gel strength increased slowly which is considered weak, but in 3.56g concentration is decreased at 10 seconds which is not correct, the ability to maintain a proper value of the gel strength depends on the effect of solid control, overall the gel strength increased gradually which is good, but for 7.1 g the gel strength increased a lot which will apply high pressure to the formation leading to surge or swab which was mentioned previously.

8

Gel strength 25

23

20

18

18

15 15

18

17

15

13

13

10 4

5 0

Bentonite WBM

5%Bentonite + 0.71FCS

5%Bentonite + 1.428FCS

gel strength 10 s

5% Bentonite + 3.56FCS

5%Bentonite + 7.1FCS

gel strength 10 min

Figure 9 The Gel Strength of FCS Additives

The rheological profile of FCS displays dial readings with values increasing progressively from 100 rpm dial speed to 600. Again it is seen in ( figure 10 ) below consistency curves for all A concentrations. All these curves are in a good agreement with the Bingham plastic model where the shear stress increased as a function of the shear rate shear rate. PV is the slope of shear rate/shear stress, the plastic viscosity in the ( figure 11 ) shows good behavior as it is increasing gradually with adding more concentration of the additive (fish crab shrimp peelings and scales), PV increases due to the increase in solid content, if we controlled the solid content the PV will be controlled also, we need to control viscosity since it is one of the factors that effects the ability of the mud to carry the cuttings, in mud systems we have solids that are desirable such as; bentonite and starch, and we have undesirable solids such as; limestone or sand, as the density of the mud increase, automatically the PV will increase, several methods can be implemented to reduce the PV: Dilution, shaker screens, centrifuge, and desander or desilter. And as we stated earlier high PV is undesirable most of the times as it has various consequences stated previously.

60

Dial reading

50 40 30 20 10 0 0

100

200

300

400

500

600

700

Dial spead RPM

0.71FCS

1.42FCS

3.56FCS

7.1FCS

Figure 10 Dial Reading of FCS Additive

RP

SPE-xxxx-MS

9

PV (cp) 12

11

11

5% Bentonite + 3.56FCS

5%Bentonite + 7.1FCS

10 10 8

9 7

6 4 2 0 Bentonite WBM

5%Bentonite + 0.71FCS

5%Bentonite + 1.428FCS pv (cp)

Figure 11 The PV of FCS Additive

As mentioned earlier, yield point indicates the ability of the fluid to carry cuttings in a dynamic condition. From ( Figure 12 ) beneath we can see that YP is increasing when adding more concentration of the additive, 34 YP is not good for all formation, and higher YP will result in higher frictional pressure loss which is not recommended, there is no specific range for YP, it depends on the formation type, size of the hole, section to be drilled and mud type, best or optimum yield point from this figure is o.714g concentration, the increase in frictional pressure loss will lead to loss of energy which will lead to slower flow, so we should select an optimum yield point for each situation.

YP (IB/100FT2) 40 35 30

31

32

5%Bentonite + 1.428FCS

5% Bentonite + 3.56FCS

34

26

25

20

16

15 10 5 0 Bentonite WBM

5%Bentonite + 0.71FCS

5%Bentonite + 7.1FCS

yp (lb/100ft2) Figure 12 YP of FCS Additive

Filtration properties of bentonite drilling fluids added with FCS As seen in ( Figure 13), the reference mud fluid loss is 15.4, whereas for bentonite with fish crab and shrimp peelings and scales it reduced but not a lot for the first three concentrations 0.714g, 1.428g and 3.56g, only for the last concentrations it decreased up to 5.8 ml, but it is very high concentration and not cost effective, although it can be used mixed with another additive to increase the reduction in filtration loss. Since Our project emphasis on the thickness of the mud cake not the quality of the mud cake, this is one of our limitations, neglecting the quality and looking at the thickness of the mud cake it showed really good results gradually decreasing with increasing the concentrations which show the effectiveness of the additive to reduce the mud cake.( Figure 14 )

10

Fluid loss in ml 18 16

15.4

14 12

10

10

9

10 8

5.8

6 4 2 0 Bentonite WBM

5%Bentonite + 0.71FCS

5%Bentonite + 1.428FCS

5% Bentonite + 3.56FCS

5%Bentonite + 7.1FCS

fluid loss 30 min(ml) Figure 13 Filtration Loss of FCS Additive

0.09

0.0822

mud cake in inch

0.08 0.07 0.0589

0.06

0.0589 0.0515

0.05

0.0484

0.04 0.03 0.02 0.01 0 Bentonite WBM

5%Bentonite + 0.71FCS

5%Bentonite + 1.428FCS mud cake (in)

5% Bentonite + 3.56FCS

5%Bentonite + 7.1FCS

Figure 14 Mud Cake Thickness of FCS Additive

The properties of the mud after adding EO additive: Table 3 shows the effect of diverse concentration of the onion and eggplant peelings in various mud properties; comparing with the reference point properties.

Rheological properties of bentonite drilling fluids added with Onion and Eggplant peelings First, for the gel strength, the gel strength at both conditions increased with a suitable amount, it started with 5 (lb/100 ft2) and ended with 14 (lb/100 ft2) for the highest concentration with 10s time. For the 10 min, the gel strength at the beginning was 13 (lb/100 ft2) for 0.71 concentration and increased to 21 (lb/100 ft2) for 7.1 concentration. As shown, adding more of this additive leads to increase the mud gels strength. The reason for two readings it will tell us if this mud greatly forms the gel during a wide static period or not; and since this range of gels strength considered an acceptable range and this mean the mud able to carry and hold the cuttings in static condition because low get strength will not be able efficiently to suspend the cuttings of drilling process; also, the cutting will drop once pumps are closed. ( Figure 15 )

SPE-xxxx-MS

11

Gel strength 25 21 19

20 15

13

14

13

10

14

14

8 5

4

5 0

Bentonite WBM

5%Bentonite + 0.71EO

5%Bentonite + 1.428EO

gel strength 10 s

5% Bentonite + 3.56EO

5%Bentonite + 7.1EO

gel strength 10 min

Figure 15 Gel Strength of EO Additive

The readings for the rheological profile for this additive was not good comparing to the other additives.

Onion and eggplant peelings results were less than the reference mud for the concentrations 0.71, 1.42 and 3.56; so from 100 rpm speed to 600 it was increasing with a small amount from 0.71 till 7.1 but still less than the reference mud regardless of the 7.1, it was almost equal to the reference mud. From these results, we realized that this additive is not good when talking about rheological profile since the results were below the accepted range and reference mud as shown in the ( Figure 16 ).

40 35

Dial reading

30 25 20 15 10 5 0 0

100

200

300

400

500

600

700

Dial speed RPM 0.71EO

1.42EO

3.56EO

7.1EO

RP

Figure 16 Dial Reading of EO Additive

The PV results for EO additive were disappointing and unacceptable because it gave a reversal effect on the rheological properties, for the lowest concentration 0.71 the PV was less than the reference mud PV and by adding more of this additive the PV increasing but with a small amount as shown on the( Figure 17). From this, we find that the EO additive does not work perfectly on PV same as gel strength.

Also for the YP the results were the most undesirable results because the results were less than the reference mud even with the highest concentration; as shown on ( Figure 18 ) the YP for the RP 16 (Ib/100 ft2) and when looking to the highest concentration 7.1 the YP is 11 (Ib/100 ft2) and this explains that this mud is not able to carry the cuttings up to the surface, since the gel strength is the point at which solid construction of mud breakdowns and the mud going to flow. It is the lowest pressure applied at which mud will begin to flow.

12

PV 14

12

12

10

10

8

7

8

6

6 4 2 0 Bentonite WBM

5%Bentonite + 0.71EO

5%Bentonite + 1.428EO

5% Bentonite + 3.56EO

5%Bentonite + 7.1EO

pv (cp) Figure 17 PV of EO Additive

YP (IB/100FT2) 18

16

16 14 12 10

10

9

8

11

8 6 4 2 0 Bentonite WBM

5%Bentonite + 0.71EO

5%Bentonite + 1.428EO

5% Bentonite + 3.56EO

5%Bentonite + 7.1EO

yp (lb/100ft2) Figure 18 YP of EO Additive

Filtration properties of bentonite drilling fluids added with Onion and Eggplant peelings Since the hydrostatic pressure of the borehole must be more than the formation pressure. This filtration happens when there is permeability and it allows the fluid to escape through the pores to the formation.

As shown in ( Figure 19) , EO reduced the fluid loss by increasing the concentration and this indicates that this additive can use as filtration control since it reduced the fluid loss from 10.1 ml to 5 ml.

For the mud cake thickness, this additive has an instrumental effect on reducing the mud cake thickness with an acceptable range which is 2 mm (0.0787 inches), so as shown on the ( Figure 20 ) it started with 0.059 inches for 0.71 and reduced to 0.0433 for 7.1 concentration. It’s good filtration reducer agent, but with taking in consideration it’s reversal effect in the rheological properties.

SPE-xxxx-MS

13

Fluid loss in ml 18 16

15.4

14 12

10.1

10 8

6

5.5

5

5%Bentonite + 1.428EO

5% Bentonite + 3.56EO

5%Bentonite + 7.1EO

6

4 2 0 Bentonite WBM

5%Bentonite + 0.71EO

fluid loss 30 min(ml) Figure 19 Filtration Loss of EO Additive

0.09

0.0822

mud cake in inch

0.08 0.07 0.059

0.06

0.0543

0.05

0.0444

0.0433

5% Bentonite + 3.56EO

5%Bentonite + 7.1EO

0.04 0.03 0.02

0.01 0 Bentonite WBM

5%Bentonite + 0.71EO

5%Bentonite + 1.428EO mud cake (in)

Figure 20 Mud Cake Thickness of EO Additive

Comparison between all the Friendly environmental additives at a similar concentration Under this section, the optimum selection of all the concentration from each additive will be listed with the reason behind the selection.

Comparison of additives for the concentration of 0.71 g From the ( Figure 21 ), it is a comparison between all additives and reference mud, with concentration of 0.714, as we mentioned before the gel strength is the ability of the fluid to carry cuttings in static condition, if the gel strength increases slowly the mud is considered weak, and if it is changing or increasing fast the mud is considered strong, the gel strength of B+A is good as it increased slowly and not too high to prevent causing surge or swab, and B+FCS the gel strength could be considered high for this concentration so we should be careful when adding more concentration of FCS, while B+EO shows very good gel strength increased fast but in moderate range.

The ( Figure 23 ) shows the results of filtration loss of the 0.714g concentration of different additives, you can see that adding Avocado (B+A) decreased the fluid loss dramatically which shows an excellent behavior as an LCM agent, while B+FCS and B+EO decreased the fluid loss but not as much as B+A, which qualifies B+A as the best additive.

The results at ( Figure 24 ) demonstrate that all of the additives decreased the mud cake thickness, but B+FCS shows the highest reduction in mud cake thickness, of course neglecting the quality of the mud

14

cake thickness, so from the figure above the best additive for decreasing the mud cake thickness is B+FCS (fish crab shrimp) Finally, the B+A is the best option and it’s suitable for most of the conditions regarding the most optimum rheological and filtration properties ( Figure 22 ), the second option can be the B+FCS. EO is neglected because it’s giving a reverse effect on the rheological properties.

Comparison of additives for the concentration of 1.428 g As mentioned the gel strength shouldn’t be too high because it will apply pressure to the formation which might cause differential sticking, reduction in hole size, surge and swab, B+A and B+FCS shows a very close results and they increased slowly which is good, but B+EO increased fast and might cause problems in the hole but it is within a proper range.

As shown in the ( Figure 23 ) B+A and B+EO shows a really good reduction in filtration loss, but B+FCS didn’t change a lot so adding 1.428 g will be considered the same as 0.714g since it was 10 ml and know it is 9 ml From the ( Figure 24), the filtration thickness of B+A remained constant and less than 2 mm which is considered good and cost-effective, so we can use 0.714g and it will give you the same good result as 1.428g, B+FCS mud cake thickness remained constant, for B+EO it showed reduction not a lot but good reduction better than 0.714g ( Figure 22 ) Shows that the PV for A additive still constant while the YP increased; FCS is behaving the same as the former additive. While EO still has no effect on the rheology.

Comparison of additives for the concentration of 3.56 g On this concentration it’s obvious in the( Figure 21 ) that after 10 seconds the B+A had a higher gel strength ability as well as at 10 minutes; the B+EO had nearly an approximate result as the B+A while the B+ FCS was the lowest among them.

Also, in the ( Figure 23 ) the B+A remained constant in the fluid loss, the EO was the lowest and the FCS still high compared with the rest of the environmentally friendly additive which illustrates slow to weak effect in adding more concentration and reducing the fluid loss.

Finally, the filter cake thickness (Figure 24 ) of the B+A stayed constant which indicated that is not affected by the amount of the concentration while for the B+FCS the mud cake thickness reduced which is good that’s mean that the thickness of the mud cake is directly proportional with the concentration of the additive; the same is for the B+EO. ( Figure 22 ) illustrate that the rheology of the FCS highly increasing followed by A additive.

Comparison of additives for the concentration of 7.1 g The B+FCS was the highest gel strength at 10 seconds as well as for 10 minutes followed by the B+A for both times and finally the B+ EO. We must take in consideration that high gel strength sometimes is undesirable because it may fracture the formation as we mentioned before. ( Figure 21 ) The B+A was the best fluid loss reducer and we can notice that it reduced the fluid loss to a great amount compared with the reference point. Followed by the B+EO then B+FCS but the difference between them is approximately nothing. ( Figure 23 ) The B+A kept it constant mud cake thickness which indicated that the filtration thickness is not affected by the concentration. While the B+FCS was higher than B+EO mus thickness as behaved in the previous concentrations. ( Figure 24 ) ( Figure 22 ) indicated that the rheology of A and FCS is very high and it abviousily exceeded the acceptable range; it may suit wells that require high YP. Comparison of additives for the PH The figure below shows the different additives with different concentration and their effect on the PH comparing with the reference mud. We can observe From the ( Figure 25) the PH decreased

SPE-xxxx-MS

15

progressively with increasing concentration and this is because of adding organic waste additive which usually decreases the PH of drilling fluids such as; Citric acid. All of the additives showed a good PH control and was at all the concentrations.; but reducing the PH must be in consideration.

Gel Strength (lbf/100ft2)

gel strength 25 20 13

15 10

5

13

16

19 15

15

23

22

19 15

15

18

15

18

18 13

14

13 5

4

21

19

17

14

14

10 10

12 11

8

0

Concentration

gel 10 s

gel 10 min

Figure 21 Gel Strength Comparison

plastic viscosity (cp) & Yield point (lb/100ft2)

Rheology 40 35 30 25 20 15 10 5 0

26

32

29

28

34

32

31 26

16 7

10

10

11

10

9

10

11

Concentration pv (cp)

yp (lb/100ft2)

Figure 22 Rheology Comparison

11

6 8

8 9

16

Fluid loss (ml)

fluid loss 30 min(ml) 18 16 14 12 10 8 6 4 2 0

15.4 10 6.5

6.5

10

9

6.5

5.8

3.9

concentration Figure 23 Fluid Loss Comparison

Mud cake thickness (in)

mud cake (in) 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0

0.0822 0.0692 0.0692 0.0692 0.0692 0.0589 0.0589

0.0515 0.0484

Concentration Figure 24 Filter Cake Thickness Comparison

0.059

0.0543 0.0444 0.0433

SPE-xxxx-MS

17

PH 12 10

9.8

9.79

9.74

8.87

9.67

9.56

9.42

8.04

8

9.22

9.44

9.2

8.61

7.7

6 4

2 0

Figure 25 PH Comparison

Conclusion From all of the plots and results shown in the previous pages that were conducted in 13 different lab tests of 3 different environmentally friendly drilling fluid additives to examine their feasibility to be drilling fluid additives in actual oil and gas fields, the effect of these additives on the rheological properties, filtration loss, PH as well as the mud cake thickness neglecting the quality of the mud cake considering only the thickness of the mud cake was studied intensively.

Based on the comparison of the different additives with the reference mud which is bentonite only water-based mud, it was concluded that only two of the additives gave maximum results of yield point and gel strength up to 200% and 169% respectively, while it reduced the fluid loss up to 42%, Whereas Eggplant and onion peels showed reduction in the rheology of the mud up to 50%.

It can be found that the best additives that were added to the drilling fluid are additives with Avocado peel concentration 0.714g and (Fish Crab shrimp) peels and scales 0.714g. It was observed that both additives increased the yield point and Gel strength with minor difference between them approximately 200% and 169% respectively, neglecting the effect on plastic viscosity due to the increase in solid content compared to the reference mud sample. The 0.714g Avocado peel sample decreased the filtration loss up to 42% also a reduction in mud cake thickness to 1.76 mm and kept constant throughout all concentrations, for the filtration loss it can be fixed by adding bridging materials such as calcium carbonate. The results show a high potential for using Avocado peel and fish crab shrimp of 0.714 g concentration for optimum Rheology of YP and gel strength, and Avocado peel as LCM agent, all of the three additives showed good potential in being PH control agents they decreased the PH gradually, like the organic acid used nowadays to decrease the PH. For optimum decision Avocado peel 0.714g will be the best choice for them due to its low concentration and optimum Rheology of YP and gel strength, it can also be used as LCM agent as well as a PH control agent, our final selection avocado peel 0.714g can be used for overbalanced and underbalanced drilling after adding other materials for better results, the density of our mud is almost 8.8 ppg so if we are drilling in a low formation pressure zone than we will be drilling in an overbalanced technique.

Acknowledgment This research was supported and encouraged by Kuwait Oil company; special thanks and appreciation for Senior Engineer Nawaf Al- Shuaibi as well as Mud Engineer Abdulrahman Hamada from Drilling and Workover Department for sharing their pearls of wisdom with us during the course of this research. Additionally, We express gratitude for our Supervisor Dr.Biltayib Biltayib and Cooperative Supervisor Eng. Koshy Vaidian who provided vision and expertise that significantly aided the research. We acknowledge Dr. Murtadha Al-Sabaa for supporting us with for supporting

18

comments that greatly improved the manuscript and Engineer Kingsley Amadi for providing us with particular information and result analysis. We would also like to show our gratitude to the Australian College of Kuwait who provided us with the different instruments and equipment’s that helped us to conduct our experiments. We are also enormously appreciative to (\/) for their comments on a former version of the script, although any errors are our own and should not tarnish the reputations of these esteemed persons.

References 1. Adam T. Bourgoyne Jr., Keith K. Millheim, Martin E. Chenevert, and F. S. Young Jr.: “Applied Drilling Engineering,” SPE Textbook Series, 1991.

2. Drilling fluid. (2006). Baker Hughes.

3. Drilling formulas.com. drilling formulas. pH in Drilling Mud (Water Based Mud) , http://www.drillingformulas.com/ph-in-drilling-mud-water-based-mud/(accessed 05 April 2018).

4. Enamul Hossain, M. and Mohammed, W. 2016. The use of grass as an environmentally friendly additive in water-based drilling fluids. http://dx.doi.org/10.1007 5. Fedairo , A. and Ameloko, A. 2011. Environmental impact evaluation of a safe drilling mud. Journal of Canadian Petroleum Technology 38 (3): 1—9. SPE152865. http://dx.doi.org/10.2118/152865.

6. Hossain, M.E. & Wajheeuddin, M. Pet. Sci. (2016) 13: 292. https://doi.org/10.1007/s12182-016-0083-8 7. H.C.H. Darley and George R. Gray: “Composition and Properties of Drilling and Completion Fluids,” 5th Edition, 1988.

In-Text: (Fedairo and Ameloko 2011) 8. Younkin WE, Johnson DL. The impact of waste drilling fluids on soils and vegetation in Alberta. In: Proceedings of symposium, research on environmental fate and effects of drilling fluids and cuttings, Lake Buena Vista, 1980; pp. 21–4 9. James, A. (2017). Drilling Mud Laboratory. [online] Slideshare.net. Available at: https://www.slideshare.net/akincraig/drilling-mud-laboratory [Accessed 30 Nov. 2017].

10. Max R. Annis and Martin V. Smith: “Drilling Fluids Technology,” Exxon Company, U.S.A., 1996.

11. Mian, C. 2011. An environmentally friendly drilling fluid. http://dx.doi.org/10..

In-Text: (Mian 2011) 12. OFI Testing Equipment, Inc.: “Instructional Manuals,” 2007.

13. Schlumberger, 2018. Drilling Mud: Monitoring and Managing It. https://www.slb.com/~/media/Files/resources/oilfield_review/ors89/jul89/4_drilling_mud.pdf .

SPE-xxxx-MS

19