Lab 8.docx

PET 327 COVENANT UNIVERSITY CANAANLAND, OTA

PETROLEUM ENGINEERING LABORATORY EXPERIMENT 8

EVALUATION OF DRILLING FLUID METHYLENE BLUE CAPACITY

BY

NYONG, A.F (Matric No. 16CN021106) GROUP 1

Date Performed: 22-03-2019 Date Submitted: 26-03-2019

ABSTRACT

With differing formations spanning different areas and zones of the earth, it is important to clearly determine the reservoir characteristics present in a formation and know with assurance the quality of fluid being used as regards the solids present in the mud. These characteristics are subject to the content of the drilling mud. Having a knowledge of the amount of reactive clays present in our mud enables us to adjust our mud to prevent drilling problems. This data can be acquired via the methylene blue test. It is the ability of the clays present in the mud to adsorb methylene blue. This experiment was undertaken on a waterbased mud.

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LIST OF FIGURES Figure 1: Measuring Cylinders ................................................................................................................ 6 Figure 2: Mud Mixer and Steel Vessel .................................................................................................... 6 Figure 3: Weighing Balance..................................................................................................................... 6 Figure 4: Methylene Blue Test Kit ........................................................................................................... 7 Figure 5: Spot Test for End point of Methylene Blue Titration ............................................................. 10

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TABLE OF CONTENTS ABSTRACT................................................................................................................................................ 2 LIST OF FIGURES ...................................................................................................................................... 3 INTRODUCTION ....................................................................................................................................... 5 Background Study ............................................................................................................................... 5 Objective ............................................................................................................................................. 5 Aim ...................................................................................................................................................... 5 EXPERIMENTAL APPARATUS ................................................................................................................... 5 Figure 1: Measuring Cylinders......................................................................................................... 6 Figure 2: Mud Mixer and Steel Vessel ............................................................................................ 6 Figure 3: Weighing Balance............................................................................................................. 6 Figure 4: Methylene Blue Test Kit ................................................................................................... 7 PROCEDURES........................................................................................................................................... 8 Mud Preparation ................................................................................................................................. 8 EXPERIMENT ....................................................................................................................................... 8 RESULTS ................................................................................................................................................ 10 Figure 5: A picture showing Endpoint of the experiment ............................................................. 10 DISCUSSION........................................................................................................................................... 11 CONCLUSION......................................................................................................................................... 12 REFERENCES .......................................................................................................................................... 13

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INTRODUCTION Background Study Drilling fluids are important and cannot be overemphasized in the drilling process. The content of the drilling mud determines to a large extent the success of the drilling operation and the resultant effect on the formation. The experiment is a pointer to the number of active clays (drill solids and bentonite). The more ions we see in a clay that can be exchanged for methylene blue cations. When we have only a single clay type present, we can accurately estimate the reactive clay content. The methylene blue capacity is not altogether equal to the cation exchange capacity but, it is less than the CEC. The Methylene Blue Capacity of a mud is the volume in cm3 of methylene blue solution added per volume of mud. Cation Exchange Capacity is the cumulative capacity of a formation to retain exchangeable cations and it is supported by the presence of clays and the presence of organic matter among those clays. If we can know the type of clays present in the formation and in the fluid, we should be able to prevent excessive gel densities, viscosities, strengths, stuck pipe scenarios, borehole instability. In this experiment, clay particles are coated with a special dye known as methylene blue, giving the mud a blue colour until all ions present in the exchange process have been absorbed. We can say this by observing the gradual formation of the halo on the filter paper.

Objective The objective of the experiment is to measure amount of reactive solids (drill solids or bentonite) in the drilling fluid.

Aim The aim of carrying out this experiment is to determine the capacity of the clays present in the mud to absorb cations from the prepared solution and hence infer how the mud will act.

EXPERIMENTAL APPARATUS 5

1. Measuring Cylinder: It is used in measuring liquids. E.g. Water, oil.

Figure 1: Measuring Cylinders

2. Mud Mixture: A device powered electrically to stir and mix the mud components.

Figure 2: Mud Mixer and Steel Vessel 3. Weighing Balance: It is used in measuring samples e.g. Bentonite

Figure 3: Weighing Balance 4. Methylene Blue Test Kit: This set of apparatus helps to give a probable value of the solid’s exchange capacity present in the drilling fluid. It consists of a red knob for bleeder valve, a filter paper, case, a syringe, a pipette, a pipette aid, an Erlenmeyer

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flask, a medium clip, a large clip, a hot plate and a glass stirring rod. The reagents used were methylene blue solution, H2O2, deionized water and H2SO4.

Figure 4: Methylene Blue Test Kit

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PROCEDURES Mud Preparation 1. I weighed 20g of bentonite via the electric weighing balance. 2. I measured 350 ml of water in a measuring cylinder. 3. I poured the water into the steel vessel and began stirring. I carefully added the bentonite to the stirring water. 4. I waited patiently to allow the mud mixer to stir the content for a few minutes.

EXPERIMENT 1. Using the syringe, I added 2 mL of drilling fluid to the Erlenmeyer flask. Air or gas entrained in the drilling fluid were removed before injection. I stirred the drilling fluid to break the gel and collect the mud into the syringe. I gently discharged the syringe into the drilling fluid keeping the tip in the solution. Again, I drew the fluid into the syringe and delivered 2 mL of fluid to the flask. 2. I added 10 mL of de-ionized water into the Erlenmeyer flask. 3. I added 15 mL of 3% hydrogen peroxide into the flask. 4. I added 0.5 mL of 5N H2SO4 acid to the mixture. 5. Using the hot plate, I ensured the mixture boiled gently for 10 minutes. I did not allow it to boil to dryness. 6. I diluted the mixture to about 50 mL using de-ionized water. 7. I added methylene blue solution to the flask in increments of 0.5 mL. After each addition of methylene blue solution, I swirled the contents of the flask for about 30 seconds. 8. While the solids were still suspended, I removed one drop of liquid via the stirring rod and placed the drop on the filter paper. The initial end point of the titration was reached when the dye appeared as a blue turquoise ring surrounding the dyed solids. 9. When I saw the blue tint halo spreading, I shook the flask for an extra 120 seconds and placed another drop on the filter paper. If the blue ring was seen again, the endpoint was then certainly reached. 10. I avoided spilling methylene blue. 11. I thoroughly washed and dried all laboratory equipment and glassware immediately after use. 12. I also ensured methylene blue bottles were tightly closed after each use. 8

13. I ensured I did not leave the hot plate unsupervised while heating. 14. I avoided direct contact, inhalation and ingestion with and of the chemicals (hydrogen peroxide 3%, sulfuric acid 5N and methylene blue solution) used in this kit.

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RESULTS

Figure 5: A picture showing Endpoint of the experiment 1. MBC = (MB, ml)/ (Drilling Fluid, ml) = 7ml/2ml = 3.5 2. BE (lb/bbl) =

5 × 𝑀𝑒𝑡ℎ𝑦𝑙𝑒𝑛𝑒 𝐵𝑙𝑢𝑒, 𝑚𝑙 𝐷𝑟𝑖𝑙𝑙𝑖𝑛𝑔 𝐹𝑙𝑢𝑖𝑑, 𝑚𝑙

= (5 x 7)/2 = 17.5lb/bbl 3. BE (kg/m3) = 2.85 x BE (lb/bbl) = 2.85 x 17.5 = 49.875 kg/m3

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DISCUSSION The essence of this experiment as earlier stated is for one to know the amount of reactive clay present in the drilling fluids. We added methylene blue dye to the sample in consideration after applying heat and adding de-ionized water. We treated the mud with hydrogen peroxide to reduce or annihilate the effects of organic materials present in the mud. This was done in increments of 0.5 ml. From our experiment, we added in increments of 0.5 ml for about 14 times which is equivalent to 7ml looking at Figure 5. From our experiment, we calculated the methylene blue capacity to be 3.5. Our bentonite equivalent in lb/bbl is 17.5 lb/bbl which is also 49.875 kg/m3.

Some of the precautions we took during the experiment were as follows: -

I ensured I did not pipette any chemical by mouth.

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I avoided contact with sulfuric acid as it is corrosive and may cause chemical burns.

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I made sure that I did not leave the hot plate unsupervised while heating.

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I ensured the apparatus used during the experiment was stored in a clean and dry state.

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CONCLUSION From our experiment, we were able to know the methylene blue capacity of the mud and the bentonite equivalent that could adsorb the methylene blue dye. This property in collaboration with the water, oil and solids content enable us to condition our drilling mud to avoid drilling problems and achieve the specified targets in our drilling operations.

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REFERENCES 1. Engr Seteyebot Ifeanyi, Drilling Mud Manual, Covenant University, Ota, 2012, Page 27-31. 2. H.C.H Darley, George R. Gray, Composition and Properties of Drilling and Completion Fluids, Fifth Edition, Page 18-19 3. Robert F. Mitchell, Stefan Z. Miska, Fundamentals of Drilling Engineering, SPE Textbook Series, Vol. 12 Page 145-146. 4. Ofite Testing Equipment, Methylene Blue Test Kit Instruction Manual, Houston, Texas, June 2017. 5. https://www.netwasgroup.us/fluids-2/methylene-blue-capacity.html

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