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PE A 210 Drilling Fluids Lab

Second Year

2016-17

Drilling fluids

PU

PE A 210: DRILLING FLUIDS LABORATORY MANUAL 2016-2017

Presidency University Private University Estd. In Karnataka State by Act No. 41 of 2013

Dibbur-Itgalpura, Bengaluru Karnataka- 560089, India

Student detail Name: ID No.: Branch: Section: FACULTIES: Dr. Balachandran Govindswamy (Instructor Incharge) Mr. Y. Dheeraj Kumar

CONTENTS General Instructions Introduction Safety Exp. No.

1 2 3 4 5 6 7 8

Date

Marks Awarded

Topic

Signature

To prepare the mud sample with given bentonite and fresh water. To determine the Density of a mud sample using a mud balance. To determine the Density of given mud using a Hydrometer. To determine the Marsh Funnel Viscosity of a given mud sample. To determine the pH of a given mud sample. To determine the sand content in the given drilling fluid sample. To determine the resistivity of given mud sample using digital resistivity meter. To determine the Apparent Viscosity, Plastic Viscosity, Yield Point & True Yield Point of given mud sample.

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To determine the gel strength of a given mud sample.

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To control rheological parameters like Density, Viscosity and Yield point Total Marks

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GENERAL INSTRUCTIONS 1. Before coming to the laboratory, understand the theory behind the experiment that you are going to carry out. 2. You are not allowed to touch the instrument or samples or maps without the permission of the lab instructor. 3. After the class, before you leave the laboratory, wash the apparatus clean, wipe the table and keep the apparatus in proper place.

INTRODUCTION Drilling fluid can be defined as a suspension of solids in a liquid phase. Any of a number of liquid and gaseous fluids and mixtures of fluids and solids (as solid suspensions, mixtures and emulsions of liquids, gases and solids) used in operations to drill boreholes into the earth. Drilling fluid (mud) is a vital element of the drilling process. The success or failure of the mud program will largely determine whether a well can ultimately be drilled to the operator's specifications in a safe and economical manner. The drilling fluid engineer's task in designing a drilling fluid program is to derive from the variety of available mud-making materials the precise combination of physical and chemical properties needed to meet the demands of the well. Functions of Drilling Fluids Drilling fluid was introduced simply as a way to circulate rock cuttings out of the wellbore. But today, as deeper and more hazardous wells are being attempted to meet the demand of oil, drilling fluid is an increasingly important and complex part of the rotary drilling process. The basic functions of drilling fluid are following (1) Cool and Lubricate the Drill Bit and the Drill String The drilling action requires a considerable amount of mechanical energy in the form of weight-on-bit, rotation and hydraulic energy. a large proportion of this energy is dissipated as heat, which must be removed to allow the drill bit to function properly. Also, the drilling fluid helps in cooling and lubricating the drill string. (2) Remove Drilled Cuttings As the bit penetrates the formation, the rock cuttings must be removed, otherwise the drilling efficiency will decrease. In removing the cuttings there are two separate operations: - Lifting and dropping on surface the cuttings while circulating. - Suspension of cuttings while not circulating. (3) Control Formation Pressure For safe drilling, high formation pressures must be contained within the well to prevent blow-outs. The drilling fluid achieves this by providing a hydrostatic pressure just greater than the formation pressure. In practice, an overbalance of 100-200 psi is normally used to provide adequate safe guard against blowout (well-kick).

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Drilling fluid density is the controlling factor in this function:

𝑃 = 0.052 × 𝜌𝑀 × 𝑇𝑉𝐷 (4) Maintain Borehole Stability The drilling fluid should deposit a mud cake on the wall of the borehole to consolidate the formation and to prevent formation damage. A good mud cake must be thin, hard and impermeable to provide enough stability and less formation damage. (5) Transmit Hydraulic Horsepower to the Bit Drilling fluid is the medium for transmitting available hydraulic power from the pumps on surface to the bit at the bottom of the well. Optimum hydraulic power enables the hole to be cleaned. (6) Aiding Formation Evaluation Drilling fluid properties such as resistivity and conductivity are crucial in evaluation formations. The drilling fluid must be formulated to aid in the production of good logs.

SAFETY 1. The student is only allowed to work in the laboratory if, and only if, the teaching assistant is present. 2. The student must work only on authorized experiments. 3. The student must wear shoes that do not have open spaces; sandals, flip-flops or any peep toe shoes should be avoided. 4. The student may not eat, drink or smoke in the laboratory. The student must not even bring food or drink into the laboratory. 5. The student must not engage in acts of carelessness while in the laboratory. 6. This laboratory is equipped with instruments which deliver heat. Please do not touch any equipment until unless necessary. 7. Be aware of the various experiment controls (start button, stop button, speed control) for each lab. 8. Report any injury immediately for First Aid treatment. 9. Report any damage to equipment or instrument and broken glassware to the laboratory instructor as soon as such damage occurs.

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Experiment 1

Date:

Mud sample Preparation 1. AIM: To prepare the mud sample with given bentonite and fresh water. 2. Theory: Major Drilling fluids A) Water Base Fluids i) Fresh water muds: Spud mud, Natural Mud ii) Chemically treated muds: Phosphate mud, organic treated (No calcium compounds added. iii) Calcium treated muds: Lime, Calcium Chloride, and Gypsum. iv) Salt water muds: Sea water mud, Saturated salt water muds v) Oil – Emulsion Muds(Oil in water) B) Oil Base Fluids i) Oil base muds ii) Inverted Emulsion Muds (water in oil) C) Gaseous Drilling Fluids i) Air or Natural Gas ii) Aerated muds

Bentonite is used in drilling fluids to lubricate and cool the cutting tools, to remove cuttings, and to help prevent blowouts. Much of its usefulness is in the drilling and geotechnical engineering industry comes from its unique rheological properties. Relatively small quantities of bentonite suspended in water form a viscous, shearthinning material. At high enough concentrations (about 60 grams of bentonite per litre of suspension), bentonite suspensions begin to take on the characteristics of a gel (a fluid with a minimum yield strength required to make it move). So, it is a common component of drilling mud used to curtail drilling fluid invasion by its propensity for aiding in the formation of mud cake. 3. Equipment: Hamilton Beach mixer, three speed with a container is the equipment used for mixing. It is capable of rapidly incorporating and dispersing powders into the water. The particles are reduced to their finest constituent parts to expose the maximum surface area to the surrounding liquid and activate the gelling effect.

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Hamilton Beach Mixer

4. Procedure: 1. 2. 3. 4.

Measure the given amount of bentonite powder using weighing balance. Measure the given amount of distilled water using measuring flask. Take water in to the mixer container, start the mixer and slowly add the powder Continue the mixing for 10 -15 minutes until uniformity is obtained (start with low speed and increase to maximum for proper mixing) 5. Once uniformity is attained stop mixing and remove the contents to separate container. 5. Precautions: 1. The mixer container and its contents should not be touched while mixing. 2. The blades should be kept dry after use otherwise they get rusted. 3. All the parts should be wiped with dry cloth and kept dry after every use.

6. Result: Drilling fluid sample is prepared with given ___ gm of bentonite and ____ ml of water.

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Experiment 2

Date:

Mud Balance 1. AIM: To determine the Density of a mud sample using a mud balance. 2. Theory: Density is ratio of mass by volume. With simple water-based muds, density is a reliable measure of the amount of suspended solids. Density must be measured by weighing a known volume. Density can be stated in any convenient units, such as lb./gal, lb./ft3, and g/cm3. Density also measures hydrostatic pressure in the borehole and solids content of the unweighted muds. Loss of circulation may result from excessive pressure due to mud that is too dense or heavy.

3. Equipment: The density or weight of a given volume of liquid is determined by using a mud balance. A device to measure density (weight) of mud, cement or other liquid or slurry. A mud balance consists of a fixed-volume mud cup with a lid on one end of a graduated beam and a counterweight on the other end. A slider-weight can be moved along the beam, and a bubble indicates when the beam is level. Density is read at the point where the slider-weight sits on the beam at level. The arm is graduated and permits accurate measurements to within ±0.1 pounds per gallon or ±0.01 specific gravity. Calibration: OFITE mud balances are calibrated at the factory with the lid included in the mud balance kit. However, the balance should be re-calibrated, if necessary, on site. Any time a mud balance lid, or any other part, is replaced, the instrument should be recalibrated. 1. The calibration of the instrument may be easily checked by measuring the density of fresh water. 2. Fill the cup with fresh water at around 70°F (21°C), and set the rider on 8.3 pounds per gallon or 1.0 specific gravity. Add or remove steel shot from the shotwell until the instrument is in balance. Specifications: Range of the Equipment is 6.5 - 23.0 lbs/gal 0.79 - 2.72 specific gravity 49 - 172 lbs/ft3 340 - 1190 psi/1000 ft

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8

4. Procedure: 1. Remove the lid from the cup, and completely fill the cup with the mud to be tested. 2. Replace the lid and rotate until firmly seated, making sure some mud is expelled through the hole in the cup. 3. Wash or wipe the mud from the outside of the cup. 4. Place the balance arm on the base, with the knife-edge resting on the fulcrum. 5. Move the rider until the graduated arm is level, indicated by the Level bubble vial on the beam. (Bubble should be in centre of the markings and steady) 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. Note down mud temperature corresponding to density. 5. Observations:

Sample

Mud weight (ppg)

Mud weight (sp.gr)

1 2

6. Calculations:

1. 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 2. 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 3. 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 4. 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛

𝑃𝑠𝑖 𝑓𝑡 𝑃𝑠𝑖 𝑓𝑡 𝑙𝑏 𝑓𝑡 3 𝑘𝑔 𝑚3

= 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑝𝑝𝑔 ∗ 0.052 = 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑠𝑝. 𝑔𝑟 ∗ 0.433 = 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛

𝑝𝑠𝑖 𝑓𝑡

∗ 144

= 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑠𝑝. 𝑔𝑟 ∗ 1000

7. Result: The Density of a given mud samples found using a mud balance is Sample 1

Sample 2

Sp.gr Ppg Lb/𝑓𝑡 3 Psi/ft Kg/𝑚3

Sp.gr Ppg Lb/𝑓𝑡 3 Psi/ft Kg/𝑚3

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Experiment 3

Date:

Hydrometer 1. AIM: To determine the Density of given mud using a Hydrometer. 2. Theory: With simple water-based muds, density is a reliable measure of the amount of suspended solids. Density must be measured by weighing a known volume. Density can be stated in any convenient units, such as lb./gal, lb./ft3, and g/cm3. Density also measures hydrostatic pressure in the borehole and solids content of the unweighted muds. Loss of circulation may result from excessive pressure due to mud that is too dense or heavy.

3. Equipment: A hydrometer is an instrument that measures the specific gravity (relative density) of liquids—the ratio of the density of the liquid to the density of water. A hydrometer is an instrument whose function is based on Archimedes principle. This principle states that a body (the hydrometer) immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid. A hydrometer is usually made of glass, and consists of a cylindrical stem and a bulb weighted with mercury or lead shot to make it float upright. Specifications: • Range: 0.700 to 2.000 specific gravity • Consists of eight 265 mm / 10.5" glass hydrometers and a thermometer packed in a protective, foam-lined carrying case • Hydrometer scale standardized at 60°F 0.700 to 0.810 Specific Gravity 0.800 to 0.910 Specific Gravity 0.900 to 1.010 Specific Gravity 1.000 to 1.220 Specific Gravity 1.200 to 1.420 Specific Gravity 1.400 to 1.620 Specific Gravity 1.600 to 1.820 Specific Gravity 1.800 to 2.000 Specific Gravity Thermometer with range: -30 - 120°F, 1° Divisions Size: 13.5" × 10" × 2.5" (34 × 25 × 6 cm) Weight: 2 lb 10 oz (1.2 kg)

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Hydrometer set, hydrometer, Reading a Hydrometer

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4. Procedure: 1. Fill the test jar three-quarters full with mud or oil samples then slowly insert the hydrometer. 2. Spin it in the liquid to dislodge any air bubbles clinging to the glass, otherwise it could cause a test error. 3. At eye level, read the specific gravity figures on the glass stem where the surface of the liquid cuts across it. 5. Observations:

Sample

Mud weight (sp.gr)

1 2

6. Calculations:

1. 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 2. 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 3. 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 4. 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛

𝑃𝑠𝑖 𝑓𝑡 𝑃𝑠𝑖 𝑓𝑡 𝑙𝑏 𝑓𝑡 3 𝑘𝑔 𝑚3

= 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑝𝑝𝑔 ∗ 0.052 = 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑠𝑝. 𝑔𝑟 ∗ 0.433 = 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛

𝑝𝑠𝑖 𝑓𝑡

∗ 144

= 𝑀𝑢𝑑 𝑤𝑒𝑖𝑔ℎ𝑡 𝑖𝑛 𝑠𝑝. 𝑔𝑟 ∗ 1000

7. Result: The Density of a given mud samples found using a hydrometer is

Sample 1

Sample 2

Sp.gr ppg Lb/𝑓𝑡 3 Psi/ft Kg/𝑚3

Sp.gr Ppg Lb/𝑓𝑡 3 Psi/ft Kg/𝑚3

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Experiment 4

Date:

Marsh Funnel 1. AIM: To determine the Marsh Funnel Viscosity of given mud sample. 2. Theory: The viscosity of a fluid is defined as its resistance to flow. The desired viscosity for a particular drilling operation is influenced by several factors, including mud density, hole size, pumping rate, drilling rate, pressure system and requirements, and hold problems. The indicated viscosity as obtained by any instrument is valid only for that rate of shear and will differ to some degree when measured at a different rate of shear. The Marsh funnel is a simple means of making comparative viscosity measurements. “Low viscosity" is favoured for effective cleaning at the bit face and rapid settling of cuttings at the surface. "High viscosity" may be necessary to remove coarse sand from the hole or to stabilize gravel but will retard settling of the cuttings at the surface. Viscosity is defined as the ratio of shear stress to shear rate. τ α du/dy τ = shear stress, du/dy = velocity gradient τ = μ du/dy μ = viscosity in poise/ centipoise μ = τ / (du/dy)

3. Equipment: The Marsh Funnel was invented by Hallan N. Marsh in 1931. It is used to measure the time in seconds required to fill a set volume of fluid. (In the United States the volume is one quart.) The flow through the small tip at the end of the funnel is related to the rheological properties of the fluid being measured. The Marsh Funnel “viscosity” is reported as seconds and used as an indicator of the relative consistency of fluids. The more viscous the fluid the longer the time to fill one quart. Specifications: The Marsh Funnel Viscometer is conical in shape - 6" (152 mm) in diameter at the top and 12" (305 mm) long with a capacity of 1,500 cm3. A 12- mesh screen covers half of the top and is designed to remove any foreign matter and drilled cuttings from the fluid. The fluid runs through a fixed orifice at the end of the funnel, which is 2" (50.8 mm) by 3/16" (4.7 mm) in size. Calibration Check: Periodically check the calibration of the Marsh Funnel by measuring the viscosity of fresh water. Using the procedure described above, one quart (946 mL) of fresh water at a temperature of 70° ± 5°F (21° ± 3°C) should outflow from the orifice in 26 ± 0.5 seconds. If the Marsh Funnel checks out of calibration, it should be cleaned again, making sure that nothing is obstructing the outlet. 13

Standard Marsh Funnel 4. Procedure: 1. Hold the clean, dry funnel in an upright position with the index finger over the outlet. 2. Pour a freshly obtained sample of the fluid to be tested through the screen until the fluid level reaches the bottom of the screen. 3. Remove the finger from the outlet and start the stopwatch. Using the measuring cup, measure the time it takes the fluid to fill to the one-quart (946 mL) mark of the cup. 4. Measure the temperature of the fluid in °F or °C. 5. Report the time to the nearest second as Marsh Funnel viscosity and record the temperature of the fluid. 5. Observations:

Sample

1st Time (sec)

2nd Time (sec)

1 Water 2 Mud Sample

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6. Calculations: μ = ρ (t - 25) Where μ = effective viscosity in centipoise ρ = density in g/cm³ t = quart funnel time in seconds

7. Result: The viscosity of the given drilling fluid sample found using marsh funnel is _________cp and it has taken ______ seconds for 1 quart to flow.

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Experiment 5

Date:

PH Meter 1. AIM: To determine the pH of a given mud sample. 2. Theory: The pH of a solution is the logarithm of the reciprocal of the (H+) concentration in grams moles per litre, The acidity and the alkalinity of the drilling fluid can be measured by the concentration of the (H+) ion in the fluid. As for instance, if H+ is large (1 x 101), then the (OH-) hydroxyl concentration is very low (1 x 10- 13), the solution is strongly acidic. If the (OH-) concentration is (1 x 10- 1) very high then (H+) concentration is very low then the solution is strongly alkaline. It can be expressed as:

Therefore, if the pH of a mixture drops from 7.0 to 6.0, the number of (H+) increase ten times. The pH of a mud seldom is below 7 and in most cases fall between 8 and 12.5 depending upon the type of mud. The pH is important because the pH affects the solubility of the organic thinners and the dispersion of clays presents in the mud. Alkalinity or acidity is commonly expressed as pH. On the scale 7 is neutral, less than 7 is acidic and greater than 7 is basic or alkaline. Each unit represents a tenfold change in hydrogen-ion concentration (for example, a pH of 5 means ten times as acid as a pH of 6; or pH of 10 means ten times as basic as a pH of 9). The optimum performance of some mud systems is based on control of pH. The effectiveness of bentonite is greatly reduced in an acid environment. Before mixing bentonite, pH of the water should be adjusted to 8 to 9. Contamination of mud by cement will raise the pH to 10-12. If the mud is acidic then the mud will be corrosive and if it is more alkaline also it will not be in suspension and gets precipitated. 3. Equipment: Methods of measuring pH in the laboratory: 1. The pH Paper: The pH paper strips have dyes absorbed into the paper display certain colours in certain pH ranges. It is useful, inexpensive method to determine pH in fresh water muds. The main disadvantage is that high concentrations of salts (10,000 ppm chloride) will alter the colour change and cause inaccuracy. 2. The pH Meter: The pH meter is an electric device utilizing glass electrodes to measure potential difference and indicate directly by dial reading the pH of the sample. The pH meter is the most accurate method of measuring pH. 16

Precautions: For best results, keep the ISE capped dry and pH/ORP electrode bulb wet. Store the pH/ORP glass bulb with pH electrode storage solution. NEVER use deionised water for storage. Wash electrodes with clean water after each use. Your ISE or pH electrode is susceptible to contamination or dirt. Clean as needed using mild detergent and warm water. Blot the probe gently with a soft tissue paper. Avoid excessive drying of the glass membrane and avoid touching it with your fingers. Recalibrate after cleaning.

Digital pH Meter 4. Procedure: 1. Before measurement, rinse pH/ORP electrode or Ion Selective Electrode and temperature probe with clean water to remove any impurities stuck onto the bodies of probes. 2. Power on the meter using ON/OFF key. Press MODE key to select your desired mode of operation (pH, mV, Ion, or Temperature). 3. Dip and stir both probes gently into given test sample, swirl gently and wait for the reading to stabilise. Note the reading. Freeze the displayed if desired. 4. Rinse probes with clean water before taking next reading or storage 5. Observation:

Sample

pH ( using pH paper )

pH (pH meter)

1 2 6. Result: The pH of the given sample using pH meter is _________ for sample1 and _________ for sample 2.

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Experiment 6

Date:

Sand Content 1. AIM: To determine the sand content of a given drilling fluid. 2. Theory: Periodic sand content determination of drilling mud is desirable, because excessive sand may result in the deposition of a thick filter cake on the wall of the hole, or may settle in the hole about the tools when circulation is stopped, thus interfering with successful operation of drilling tools or setting of casting. High sand content also may cause excessive abrasion of pump parts and pipe connections. Sand content is determined by elutriation, settling, or sieve analysis. 3. Equipment: The OFITE Sand Content Kit determines the volume percent of sand-sized particles in the drilling fluid. Sand content (API method) is defined as the percentage by volume of solids in the mud that are retained on a 200-mesh sieve. Abrasiveness is not dependent on size alone, however, but upon the hardness and shape of the particles and may be severe with particles even smaller than 200-mesh (74 microns). The volume of sand, including the spaces between the grains, is expressed as a percentage of the volume of the drilling fluid. The value read from the measuring tube is reported as: "% by Volume".

Sand Content Kit

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4. Procedure: 1. Fill the sand content tube to the indicated mark with mud. Use the wash bottle to add water (or diesel oil for oil-based drilling fluids) to the next mark. Close the mouth of the tube and shake vigorously. 2. Pour the mixture onto the clean screen. Discard the liquid passing through the screen. Add more fluid from the wash bottle to the tube, shake, and again pour onto the screen. Repeat until all the drilling fluid has been washed out of the tube. 3. Flush the screen with fluid from the wash bottle to free the sand remaining on the screen of any remaining mud. 4. Fit the funnel upside down over the top of the screen. Slowly invert the assembly and insert the tip of the funnel into the mouth of the glass measuring tube. Wash the sand into the tube by spraying a fine spray of fluid from the water bottle through the screen (tapping on the side of the screen with a spatula handle may facilitate the process). Allow the sand to settle. 5. Using the scale on the graduated tube, read the volume percent of sand. Report this along with the source of the mud sample. 5. Observations:

Sample

Sand %

Sand %

1 2

6. Result: The sand content of the given drilling fluid found using Sand content kit is ______% for sample 1 and _______% for sample 2.

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Experiment 7

Date:

Digital Resistivity meter 1. AIM: To determine the Resistivity of given drilling fluid. 2. Theory: The resistivity of a drilling mud a measure of the resisting power to the flow of an electric current. It is influenced by the dissolved salts (ppm) or (gpg, grain per gallon) in the water portion and the insoluble solid material contained in the water portion. The greater the concentration of dissolved salts, the lower resistivity of the solution. Unlike metals, the resistivity of a solution decreases as temperature increases. It is necessary to measure resistivity because the mud, mud cake, mud filtrate resistivity exert a strong effect on the electric logs taken in that mud. The mud resistivity varies greatly from the actual resistivity values due to the various factors encountered in the actual operation. 3. Equipment: The OFITE Digital Resistivity Meter is a portable measuring device designed to give a quick, reliable measurement of the resistivity of a small sample expressed in ohmmeters. The transistorized meter accurately measures the resistivity of fluids, slurries and semisolids having resistivities from 0.01 to 400 ohm-meters. The digital display shows both resistivity (in ohm-meters) and concentration of NaCl (in ppm, kppm, and gr/gal), as well as temperature (in °C or °F).

Specifications: Cell Length: 3.4" (86.4 mm) Carrying Case: 8.0" × 5.0" × 3.5" (203 × 126 × 88 mm) Resistivity Range: 0.01 – 400 ohm-meters Temperature Range: 14 – 140°F (-10 - 60°C) NaCl Range: .2 – 300 kppm

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Digital Resistivity Meter

4. Procedure: 1. Press the “Power/Exit” button to turn the unit on. The display screen will show the temperature and either Resistivity. 2. To change the measurement reading, press the “Menu” button, then press the “Units” select Resistivity. Use the suction bulb to pull the sample into the Lucite cell. Empty and refill, the cell several times to thoroughly wet the cylinder walls. 3. When testing semi-solid fluid, prepare a sample of uniform moisture content and fill the slot on the top of the cell completely. 4. Wait for the sample to reach room temperature. 5. Record the Resistivity/Concentration and Temperature from the display. 5. Observation:

Sample

Resistivity ( ohm-m )

Resistivity (ohm-m)

1 2 6. Result: The Resistivity of the given sample using pH meter is _________ for sample1 and _________ for sample 2.

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Experiment 8

Date:

MUD RHEOLOGY TEST 1. AIM: To determine the Apparent Viscosity, Plastic Viscosity, Yield Point & True Yield Point of given mud sample. 2. Theory: Rheology is a more complex study of the flow of matter; mainly liquids, but also soft solids, gels, pastes and even sold materials that exhibit some level of flow (i.e. do not just deform elastically). Rheology applies to substances that have a complex structure, including: muds, sludge’s, suspensions, polymers, petrochemicals and biological materials. The flow of these complex materials cannot be characterized by a single value of viscosity, instead viscosity changes with changing conditions. Viscosity is defined as the resistance of a fluid to flow and is measured as the ratio of the shearing stress to the rate of shearing strain. Two types of fluid characterizations are: 1. Newtonian (true fluids) where the ratio of shear stress to shear rate or viscosity is constant, e.g. water, light oils, etc. and 2. Non-Newtonian (plastic fluids) where the viscosity is not constant, e.g. drilling muds, colloids, etc.

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3. Equipment: a) The Rheometer is a direct-indicating, manually operated, rotational viscometer. The instrument is powered by a hand crank, which drives the spindle through a precision gear train. The shift cam selects between fixed speeds of 300 and 600 RPM. A Knob on the hub of the shift can determines gel strength. During operation, fluid is contained in the annular space between two concentric cylinders. The outer cylinder, or rotor, is driven by the hand crank. The inner cylinder, or bob, is restrained by a torsion spring. A dial attached to the torsion spring indicates bob displacement due to friction. The instrument constants have been adjusted so that plastic viscosity and yield point can be calculated using the 300 and 600 RPM readings.

Rheometer The Rheometer has three settings: 300 RPM: Turn the shift cam all the way clockwise and turn the crank fast enough to cause slipping. 600 RPM: Set the shift cam between the 300 RPM and Stir settings and turn the crank fast enough to cause slipping. Stir: Turn the shift cam all the way counter-clockwise and turn the crank vigorously.

b) The Digital Viscometer: The OFITE Model 900 Viscometer is a true coaxial cylinder rotational viscometer, which employs a transducer to measure the induced angle of rotation of the bob by a fluid sample. The test fluid is contained in the annular space, or shear gap, between the rotor and the bob, which is attached to a 23

shaft with a biasing spring. The viscous drag exerted by the fluid creates a torque the bob, and is monitored by the transducer that measures the angular displacement if the bob. Using the angle of displacement of the bob, the processor calculates and transmits readable output of the sample characteristics in accordance with determined calculations based upon the shear rate and the bob displacement. Revolutionary improvements in stepper-motor technology by OFITE enables the Model 900 Viscometer to operate accurately at extremely low shear rates (0.01 1/s). As a stand-alone field unit, the press of a single button (MUD or CEM) prompts the viscometer to perform standard API recommended practices for the technician’s choice of Mud (Plastic Viscosity [“PV”] - Yield Point [“YP”]) or Cement rheologies. Standard speeds (600, 300, 200, etc.) are provided as single button operations on the keypad, or if another shear rate is desired, the parameters may be entered on the numbered keypad. Simply press ENTER after entering the desired shear rate and the viscometer performs the rest of the work. It is not necessary to top the motor between speed changes.

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4. Procedure: 1. Place a recently agitated sample of fluid in a suitable container. Be sure to leave enough empty volume in the cup for the displacement of the bob and rotor (approximately 100 mL). It is very important that you take the measurements as soon as possible after you retrieve the sample. 2. Immerse the rotor exactly to the scribed line and then tighten the leg lock nut to hold it in position. 3. Set the shift cam to the “Stir” position (all the way counter- clockwise) and turn the crank for about 15 seconds. While stirring, place a thermometer in the sample and record the temperature. 4. Set the shift came to the 600 RPM setting (middle) and continue cranking until the dial reading becomes steady. The time for this is dependent upon the mud characteristics. Record the dial reading. 5. Switch the shift cam to 300 RPM (all the way clockwise) and turn the crank until the dial reading becomes steady. Record the dial reading. 5. Observation: Sample no. Φ 600

Φ 300

Viscosity cp 𝜇𝑝 𝜇𝑎

𝑌𝑝

6. Calculations: i.

Plastic viscosity (in centipoise-cp): Plastic Viscosity = μ p = 600 RPM reading - 300 RPM Reading =

ii.

Apparent Viscosity (in centipoise-cp): Apparent Viscosity = 𝜇𝑎 = (600 RPM Reading/2) =

iii.

Yield Point (in lb/100 ft2): Yield Point = Y. P. = 300 RPM Reading - Plastic Viscosity =

7. Result: Following are the results obtained Sample 𝜇𝑝 1 2

𝜇𝑎

𝑌𝑝

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Experiment 9

Date:

Shearometer 1. AIM: To determine the gel strength of a mud sample. 2. Theory: Rheology is a more complex study of the flow of matter; mainly liquids, but also soft solids, gels, pastes and even sold materials that exhibit some level of flow (i.e. do not just deform elastically). Rheology applies to substances that have a complex structure, including: muds, sludge’s, suspensions, polymers, petrochemicals and biological materials. The flow of these complex materials cannot be characterized by a single value of viscosity, instead viscosity changes with changing conditions. Viscosity is defined as the resistance of a fluid to flow and is measured as the ratio of the shearing stress to the rate of shearing strain. Two types of fluid characterizations are: 1. Newtonian (true fluids) where the ratio of shear stress to shear rate or viscosity is constant, e.g. water, light oils, etc. and 2. Non-Newtonian (plastic fluids) where the viscosity is not constant, e.g. drilling muds, colloids, etc. The Gel strength is a function of the inter-particle forces. An initial 10-second gel and a 10-minute gel strength measurement give an indication of the amount of gelation that will occur after circulation ceased and the mud remains static. The more the mud gels during shutdown periods, the more pump pressure will be required to initiate circulation again. Most drilling muds are either colloids or emulsions which behave as plastic or Non-Newtonian fluids. The flow characteristics of these differ from those of Newtonian fluids (i.e. water, light oils, etc.) in that their viscosity is not constant but varied with the rate of shear. 3. Equipment: Many drilling fluids tend to develop excessive gel or shear strength under static conditions when the mud is not circulating in the well bore. This is especially noticeable at elevated temperatures. Excessive shear strength results in high pump pressures required to "break circulation", and may result in loss of circulation and difficulties in logging, perforating and other down-hole operations. The Shearometer may be used to estimate the extent to which the drilling fluid will develop excessive gel strength, and is the primary measuring device used in the determination of the gel strength of a drilling fluid. The set consists of two hollow shear tubes (3.5" long × 1.4" ID) weighing 5 grams each and a stainless steel sample cup with a graduated scale mounted vertically in the centre of the cup base. The scale measures gel strength in pounds per 100 square feet.

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Shearometer 4. Procedure: 

Initial Gel Strength: Ensure the sample cup and scale are clean and dry before beginning the test. There should also be a way to accurately measure elapsed time. A stopwatch is ideal for this.

1. Wet the hollow Shearometer tube and wipe away the excess water. 2. Pour a freshly agitated drilling fluid sample into the stainless steel sample cup. The fluid level should be even with the bottom line on the scale. 3. As soon as the surface of the fluid is calm and steady, carefully fit a hollow Shearometer tube over the measuring scale protruding up from the drilling fluid sample and lower the tube to the surface of the fluid. 4. Release the Shearometer tube and let it sink into the fluid for one minute, as measured from the instant the tube is released. The tube may be kept vertical by gently guiding it with your fingers if necessary. 5. After the one minute time period has elapsed, read and record the scale reading visible at the top of the Shearometer tube. The reading should be reported in pounds per 100 square feet as initial gel. 

10 Minute Gel Strength: Ensure the sample cup and scale are clean and dry before beginning the test. There should also be a way to accurately measure elapsed time. A stopwatch is ideal for this.

1. Wet the hollow Shearometer tube and wipe away the excess water. 2. Pour a freshly agitated drilling fluid sample into the stainless steel sample cup. The fluid level should be even with the bottom line on the scale.

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3. Allow the fluid to stand undisturbed for 10 minutes or for some other time period if so desired. 4. Carefully fit a hollow Shearometer tube over the measuring scale protruding up from the drilling fluid sample and lower the tube to the surface of the fluid. 5. Release the Shearometer tube and let it sink into the fluid for one minute, as measured from the instant the tube is released. The tube may be kept vertical by gently guiding it with your fingers if necessary. 6. After the one minute time period has elapsed, read and record the scale reading visible at the top of the Shearometer tube. The reading should be reported in pounds per 100 square feet, for the time that has elapsed since the fluid was poured into the cup

5. Observation:

Sample 1

Initial Gel strength (lb/100ft)

10 min- gel strength (lb/100ft)

1st Measure 2nd Measure 6. Result: The determined Gel-strength for given drilling fluid using Shearometer is ____lb/100ft of initial strength and ______ lb/100ft of 10min gel strength.

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Experiment 10

Date:

CONTROL OF MUD WEIGHT 1. AIM: To control rheological parameters like Density, Viscosity and Yield point (A) EFFECT OF ADDING BENTONITE ON MUD PROPERTIES FOR FRESH AND SALT WATER BASE MUD: Procedure 1. To 400cc batch of fresh water base mud add 5 and 10 grams of bentonite and stir for 10 minutes. (Separately) 2. Measure the density lb/gal, viscosity c.c. (apparent and plastic) and yield point lb/100 ft, using the Rheometer for every batch. 3. Add 20.6 ml of 10% by weight salt water to every batch. Stir for 5 minutes and repeat step (2). 4. Report all the results (density, viscosities, and yield) for every batch in a convenient table. Plot them versus the amount of bentonite in gram in two plots, one for fresh water and the other for salt water.

(B) EFFECT OF ADDING WEIGHT MATERIAL (BARITE): Theory Barite was first used, in California, in a well being re-drilled with cable tools in 1923. According to that case, density of the mud was raised to 90 lb/ft3 (1.44 gr/cm3 to control gas in flow and to stop caving. One function of barite has developed - the preparation of a temporary high density plug formed from slurry of a barite in water (2.65 SG). Such slurry contains the maximum concentration of barite that is used - about 750 lb/bbl (2100 kg/cm3). The minimum concentration of barite might be as low as 10 lb/bbl (28 kg/m3), although usually it would be substantially higher. The quantity of barite required to raise the density of a given volume of mud a specific amount can be readily calculated from the relation, in consistent units:

where ρf = Final Mud Density ρo = Original Mud Density ρB = Barite Density = 35.82 ppg V O = Original Mud Volume 29

V B = Barite Volume Wt B= Barite Weight Test Procedure 1. Calculate and list the amount of barite required to increase the density of each batch from 8.6 ppg to 9, 10, 11 and 12 ppg. 2. Obtain 400 cc of original base mud (density 8.6) 3. Add the calculated amount of barite to each batch, stir for about 2 minutes and measure the Apparent and Plastic Viscosities and Yield Point. 5. Tabulate the results and plot the density (ppg), viscosity (apparent and plastic) and yield point versus the amount of barite added. (C) WATER-BACK (ADDING WATER TO A CHEMICALLY TREATED MUD): 1. Obtain a 350 c.c. of water base mud of 13.5 ppg weight and 9.5 pH. 2. Add water incrementally and measure the Mud weight every time to reach 10.5 ppg 3. Measure the viscosity and gel-strength and check if any change occurred. 4. List your results in an appropriate table. Observations

(A)

Amount of bentonite added 5 gm 10 gm 5 gm + salt water 10gm + salt water

Density

Plastic viscosity

Apparent viscosity

Yield point

Amount of barite added

Density (ppg) 9 10 11 12

Plastic viscosity

Apparent viscosity

Yield point

Amount of water added

Density

Plastic viscosity

Apparent viscosity

Gel strength

(B)

(C)

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Results

(A) As per tabulations _____________________________________________________

(B) As per tabulations_____________________________________________________

(C) As per tabulations______________________________________________________

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