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Benchtop Consistometer

Operating Instructions

Table of Contents

• Introduction
• Description
• Features
• Requirements
• Specifications
• Components

• Setup

  • Consistometer
  • Chart Recorder
  • Temperature Controller
  • Potentiometer Indicator

• Operation

  • Filling the Slurry Cup
  • Loading the Test Cell
  • Completing the Test

• Maintenance

  • Potentiometer Calibration
  • Potentiometer

Introduction

During cementing operations, the time required for a cement slurry to set is of primary concern. Under an ideal situation, minimal time would be required to successfully pump the slurry, which immediately upon placement, begins to develop compressive strength. However, if insufficient time is allowed to fully pump the cement, it will be necessary to drill the cement remaining in the casing string. Remedial operations such as this are very costly. Conversely, cements that are successfully placed, but require considerable time to cure, consume valuable rig time, which is also quite costly. Laboratory tests should be conducted under simulated reservoir conditions to examine the actual thickening time of the slurry. The OFITE Benchtop Consistometer was specifically engineered to determine the thickening time of well cements under simulated downhole pressures and temperatures.

Description

A cement is mixed and poured into the slurry cup assembly. The slurry cup is placed into the test vessel and pressure is increased via an air-driven hydraulic pump. A PID temperature controller governs an internal heater, which maintains the necessary temperature profile, while a magnetic drive mechanism rotates the slurry cup assembly at 150 RPM. A potentiometer controls an output voltage, which is directly proportional to the amount of torque the cement exerts upon an API-approved paddle. A chart recorder registers cement consistency and temperature as a function of time. Temperature and consistency are digitally displayed via LED indicators.

Features

• Pressure generated via an air-driven hydraulic pump
• Drive table is rotated with a magnetic drive
• External cooling jacket aids cooling of test cell
• Electronic timer with alarm, elapsed 0.1 minute resolution
• Deadweight calibration unit included
• Temperature and consistency alarms provide automatic shutdown
• Safety head with rupture disk are provided
• Unit is fully capable of testing cements in strict accordance to the guidelines as stated in API Specification 10

Requirements

• Air/Nitrogen Supply (100 - 150 PSI / 690 - 1,035 kPa)
• Water Supply for Cooling (40 PSI / 276 kPa)
• Water Drain
• 220 Volt, 50/60 Hz, 25 Amp electrical power supply

Specifications

Components

• 120-90 OFITE MODEL 130 BENCHTOP CONSISTOMETER 16;000 PSI; 400°F 220V

• Optional

• 120-91 SPARE PARTS FOR ONE YEARS OPERATION FOR NO. 120-90

Setup

Consistometer

1. Carefully remove the instrument from the wooden crate and place it on a stable surface.

2. Connect an air or nitrogen (100 - 150 PSI / 690 - 1,035 kPa) supply to the air supply on the back of the instrument.

   This unit uses ¼" NPT female connectors for all supply lines.

3. Connect the drain and coolant supply lines, also on the back of the unit.
4. Make sure all electrical switches are turned off and the unit is grounded. Make the necessary electrical connections in accordance with local codes.
5. Plug the cable into the top port on the unit cabinet and connect the other end to the port on the back of the Control Box.
6. To fill the oil reservoir, remove the oil reservoir cap and pour mineral oil into the reservoir until it is full. Replace the cap. Make sure the seal is air tight. Use the sight glass on the side of the reservoir to check the oil level. The oil level should be about ½" from the top of the sight glass.
   

Chart Recorder

The OFITE Benchtop Consistometer includes a Eurotherm Chessell 5100V chart recorder for displaying and recording test data. It features a removable drive for easily transferring test data to a PC for processing. The unit is setup to automatically record data onto the disk during the test. However, for this feature to work, you must have the disk inserted into the drive when the unit is powered on. Otherwise, the data must be manually archived at the end of the test.

It is strongly recommended that you carefully study the Eurotherm Chessell 5100V instruction manual before using this equipment.

To manually archive test data:

1. Press the "Root Menu" button.

   
2. Press "Operator" from the root menu.

3. At the top of the screen, choose "Archive" and then choose "Disk".

   

4. Now choose the data you wish to archive and press the appropriate button.

   When the archive process starts, you will see a blinking green light at the top, right-hand side of the screen. When this light stops blinking, the archive process is complete.

The chart recorder is shipped to you with a pre-programmed configuration file. It is highly recommended that you do not change any of these settings. However, in case of emergency, it is possible to restore your configuration from the disk that is shipped with the unit.

1. At the top of the screen, press "Save/Restore" and choose "Restore".
2. Make sure all four options are selected, then touch the "File Name" field.
3. Press the up arrow to access the root directory.
4. Select "Removable" and press the down arrow to access the disk.
5. Choose the file titled "config" and press "Open".
6. When the progress bar at the top of the screen stops, the restore process is complete.

To transfer the test data to a PC:

1. Remove the disk from the chart recorder and insert it into the appropriate drive on the PC.
2. From the Start Menu, select "Programs" then "Eurotherm" and then click "Review". This will open the Eurotherm Review software application.

3. From the "File" menu, select "Transfer" and then click "Files".

   
4. Click the "Browse" button, then choose the appropriate drive for your removable media. Open the "History" folder and select the files you wish to transfer.

5. Type a name in the "Name" field and click "OK".

   At this point you will receive a warning message. Click "OK" again.

6. When the file transfer is complete, go to the "File" menu and click "New Chart".

7. Click "Add Point".

   
8. From the "Instrument" drop-down menu, choose the name you selected in step 5.
9. Choose "Group 1" from the "Log Group" menu.

10. Now, select the Point IDs you wish to display on the chart. Hold down the "CTRL" button to select more than one. Click "OK".

    

11. The software will now create the chart based on the data collected from the test.

    

12. To jump directly to a specific data point, click the "Go To" button at the top of the screen. Choose the data point you wish to view and click "OK".

    

Temperature Controller

The Eurotherm Model 2404 Temperature Controller is the most important component of the temperature control system and it is strongly recommended that operators carefully study the Model 2404 instruction manual included with the Consistometer.

If a test requires a custom program, it is important to build and save the program prior to creating the slurry and loading the slurry cup.

Below is an example that illustrates how to program the controller. In this example, the target temperature is 150°C, which is obtained at a rate of 2.5 degrees per minute. The target temperature of 150°C is maintained for the duration of 180 minutes (3 hours), after which you want to stop the heat.

Press the "Page" button three times, and you will see "ProG List." Use the scroll button to decide which setting to change. Use the arrow buttons to change the values for that setting.

Temperature Controller

For the test described above, you will want the following settings:

To run the test, push and hold the "Run/Hold" button until the light for Run turns on. To stop the test, push and hold the "Run/Hold" button until the light for Run and Hold both turn off. Be sure and turn the "HEAT" switch off as well.

The temperature controller utilizes a high alarm setpoint which will bring the unit to an alarm condition if the temperature ever exceeds the set value. This value is defaulted to 200°C or 400°F, but can be programmed to different values.

An alarm condition will also occur if the slurry thermocouple is unplugged.

When an alarm condition occurs, the unit will automatically stop the heater and pressure pump, the "ALARM" switch will light up red, the "TEMPERATURE CONTROLLER" will display "IFSH", and the unit will start to beep. If the alarm condition is resolved, the heater and pressure pump will automatically be turned back on.

Potentiometer Indicator

The Benchtop Consistometer includes a built-in Eurotherm 2408i 15V Potentiometer Indicator. As the slurry cup rotates within the unit, the potentiometer creates a small voltage charge, which is displayed on the indicator. This charge increases as the strength of the slurry increases.

The potentiometer indicator features a high-voltage alarm. When the charge reaches the specified level, an alarm condition is triggered and the heater, pump, and motor are automatically shut off.

To change the alarm setting, perform the following steps:

1. Push the "Page" key twice. The display will read "AL".
2. Push the "Enter" key. The display will read "IFSH".
3. Push the up arrow key once to read the current setting.
4. Push the up or down arrow keys to change the setting.

5. After choosing the appropriate setting, press the "Page" key three times to return to the original display.

   

Operation

Filling the Slurry Cup

1. With the slurry cup disassembled, examine the threads on the inside of the cylinder. The end with the larger set of threads is the top.
2. Coat the surface of the paddle and the inside of the slurry cup with a high-temperature grease to facilitate cement removal.

3. Insert the paddle assembly all the way into the top of the cylinder.

   

   Slurry Cup Cylinder

   

   Slurry Cup Paddle

4. Slide the slurry cup lock ring on top of the paddle assembly with the two notches facing upward. Tighten the locking ring completely using the provided slurry cup tool.

   

   Slurry Cup Bottom Cell Cap

   

   Slurry Cup Locking Ring

5. Prepare the cement slurry as stated in API Specification 10.
6. Pour the cement into the slurry cup through the open bottom of the cylinder.

7. Place the metal o-ring around the threads of the bottom cap. Apply high-temperature grease to the o-ring and cap surface. Screw the cap onto the cup and tighten with the slurry cup tool.

   The slurry cup should contain enough cement slurry that it leaks out of
   the hole in the center of the cap. If it does not, remove the cap and refill the slurry cup. Do not add cement through the hole in the cap.

8. Screw the pivot bearing into the hole in the center of the cap and tighten.

9. Wipe the entire slurry cup clean to ensure that no cement remains on the outside.

   

Loading the Test Cell

Before attempting to load the test cell, ensure that the "Air To Cylinder" and "Pressure Release" valves are completely closed (turned clockwise). Also, make sure the "Motor", "Pump", and "Heat" switches are turned off.

1. Lower the slurry cup into the test cell ensuring that the slurry cup drive pins engage the drive holes at the bottom of the test cell.

   It may be necessary to start the motor briefly to confirm that the slurry cup is properly aligned inside the test cell.

2. Lower the potentiometer mechanism into the test cell ensuring that the contact springs of the potentiometer are in alignment with the test cell contacts.

   The slurry cup and potentiometer both have two holes near the top for the lift bail (provided). Use the lift bail to easily lower the slurry cup and potentiometer into the test cell.

   
   
3. To engage the drive bar of the slurry cup into the potentiometer, rotate the cup with the motor for a few seconds while applying slight pressure to the potentiometer. Note that if the unit is in an alarm condition the motor will not engage.
4. Place the o-ring into the test cell in the o-ring groove. Place the cell cap onto the cell and hand tighten.
5. Plug the thermocouple into the port on the unit cabinet. Insert the thermocouple into the hole in the top of the cell cap and tighten the thread gland finger tight. Then loosen it 1/8 of a turn.

6. With a 5/8" wrench handy, turn the "Oil Reservoir Valve" to "Fill Cell". The test cell will begin to fill with mineral oil from the reservoir. Carefully watch the top of the test cell. When oil begins leaking out of the thermocouple hole, tighten the thread gland with the wrench. This will ensure that no air remains within the test cell.

   
7. Turn on the "Motor" and "15 VDC" switches.

8. Turn on the pump. Adjust the pressure to the desired level by turning the regulator clockwise.

   If the pressure rises too high, open (counter clockwise) the "Pressure Release" valve very slowly. Close the valve immediately to prevent all of the pressure from leaking.

9. Turn the heat on and push the "Run" button on the temperature controller.

10. Turn the "Timer" switch on and push the "R" reset button on the timer display.

    The timer displays elapsed time to the nearest tenth of a minute. If an alarm condition occurs, the timer will stop. This is a troubleshooting measure that shows you the point during the test at which the alarm occurred.

    The "Timer" switch provides power to the timer and the "R" reset switch resets the timer to zero.

11. If the "Alarm" switch is not already on, turn it on now. If the "Alarm" switch is left off, the unit can still enter into an alarm condition, but there will be no visual or audio signal to notify the operator.

Completing the Test

1. When the test is complete, press and hold the "RUN/HOLD" button on the temperature controller until the "Run" and "Hold" lights are both off.
2. Turn off the "Heat" and "15 VDC" switches and turn on the "Cool" switch.
3. As the test cell cools, watch the pressure carefully. As long as the temperature is over 180°F (82.2°C), make sure the pressure is at least 1,000 PSI (6,900 kPa).
4. Once the test cell has cooled, turn off the "Pump", "Cool", and "Motor" switches.
5. Open the Pressure Release valve (counter-clockwise) all the way.
6. Turn the "Oil Reservoir Valve" to "Vent".
7. Open the "Air To Cylinder" valve (counter-clockwise). Air pressure will force the oil back into the reservoir. You will hear a hissing sound as air is released. When the hissing sound stops, close the valve (clockwise).

8. Carefully unscrew and remove the thermocouple.

   Keep a rag or paper towel handy in case extra oil leaks from the cell.

9. Unscrew and remove the cell cap. Remove the potentiometer and slurry cup.
10. Return the cell cap to the test cell to prevent dust and other matter from entering the cell. Close all valves and turn off all switches.

Maintenance

Slurry Cup

After every test, immediately disassemble the slurry cup and clean it thoroughly with soap and water. Be sure to remove any residual cement before it hardens. Hardened cement on any of the parts can cause irreparable damage.

Test Cell

After every test, examine the inside of the test cell for any cement or other debris. If necessary, wipe the inside of the cell with a rag or paper towel.

Oil Filter

If oil is not flowing from the oil reservoir to the pump, it may be necessary to replace the oil filter.

1. Open the back panel of the main unit cabinet and locate the oil filter fixture.

2. Open the fixture, remove the filter, and replace it with a new one.

   To reduce the risk of damaging the piping around the fixture, you can completely remove the entire fixture from the unit. Once you have replaced the filter, be sure to re-install the fixture with the oil flow directed downward. An arrow printed on the side of the fixture shows the direction of the oil flow.

   

Potentionmeter Calibration

The potentiometer should be calibrated once a month to ensure accurate readings.

1. Place the potentiometer on the calibration stand. Place the stand on the edge of the Consistometer and plug it into the port on the side of the unit.
2. Connect the wire clamps to the contacts. From the groove going clockwise around the unit, connect yellow, then black, then blue.
3. Slide the weight into the groove and wrap the cord clockwise around the unit one full turn.
4. Let the cord hang over the wheel and off the table.
5. Attach the hook to the cord.

6. Apply the weights to the hook according to the chart below. Steady the cord to minimize the amount of swinging.

   When adding weights, remember that the hook weighs 50 grams. Therefore, to test the potentiometer at 200g, you only need to add 150g to the hook.

7. Firmly tap the surface of the calibration stand with a pen or the blunt end of a screwdriver to settle the weights and stabilize the potentiometer.

   
8. Lift the weight about two inches directly upward and release it. Allow it to fall straight down. Observe the reading on the Potentiometer Indicator.

9. Record the reading and repeat steps 6 through 8 with each weight listed in the chart below.

   The voltage values in this chart are only examples. Every potentiometer is different and will, therefore produce different voltages. The calibration process will help you interpret the potentiometer readings provided by the Consistometer.

Potentiometer

1. The potentiometer should be kept as clean as possible. Periodically submerge the unit in solvent to remove cement and other materials.

2. Troubleshooting potential problems:

   1. If consistency (voltage) readings fluctuate, examine the resistor and verify that the top is smooth and consistent. If necessary, re-insert the resistor and lightly smooth the resistor wire with emery cloth.
   2. If the consistency (voltage) reading is zero, the resistor and contact arm may have lost contact. Adjust the contact arm either up or down. If this does not correct the problem, there may be too much space between the windings on the resistor to conduct the current. If this is the case, replace the resistor.
   3. If the potentiometer will not hold a calibration, the spring is probably either damaged or worn by corrosion. Replace the spring.

3. To install a new resistor:

   1. Remove the four small screws holding the shaft-bearing retainer to the potentiometer assembly and remove.
   2. Remove the contact arm.
   3. Carefully lift the damaged resistor away from the potentiometer. Clear the resistor groove of any foreign material.
   4. Carefully place the new resistor into the groove and ensure that it is centered between the two terminating contacts.
   5. Push the resistor completely into the groove with either a mallet or a piece of wood. It is very important to ensure that the resistor is completely inserted into the groove and that the upper surface is level.
   6. . Install a new contact arm and if necessary, bend the arm either up or down to obtain consistent contact with the resistor.
   7. Re-install the shaft-bearing retainer and calibrate the potentiometer before use.

4. To install a new calibration spring:

   1. Remove the shaft-bearing retainer and contact arm.
   2. Carefully lift the calibration spring from the potentiometer assembly.
   3. Install the new spring. When properly installed, it should tighten when the center shaft is rotated counter-clockwise.
   4. Install a new contact arm and make adjustments as necessary to obtain consistent contact with the resistor.
   5. Loosen the three adjustment screws on the underside of the potentiometer assembly and rotate the spring adjuster until the spring rests at a relaxed state.
   6. Ensure that the contact arm aligns with the contact strip and tighten the three set screws.
   7. Rotate the center shaft to ensure that the spring does not bind or rub the potentiometer housing.

   8. Replace the shaft-bearing retainer and calibrate the potentiometer.