Flow Loop Design
17.8 Differential Pressure Sensor
A differential pressure sensor was already in stock at the department. Key specifications can be found inTable 17.9. The MATLAB functionventuri pressure.min Appendix A.4 was used to calculate the pressure difference p1– p2given in Eq. 17.1. This calculation was carried out to see if the planned venturi design will give a differential pressure within the range of the sensor. It was assumed that the flow is water with a density of 1000kg/m3 and a flow rate of 100 lpm. The result was a differential pressure of 4 kPa, which is within the 0-25 kPa range of the sensor.
Table 17.9– Key specifications for the differential pressure sensor [64].
Parameter Value
Vendor Aplisens
Model APR-2000ALW
Pressure range 0-25 kPa
Accuracy ±0.075%
17.9 Pipes
There are several different types of pipes in the flow loop, with both pipe dimensions and pipe materials varying. The dimension of the test pipe section is decided based on down-scaling from offshore scales and to match the Coriolis dimensions. It was calculated that to have the same fluid velocities in the laboratory test pipe as the offshore flow line a di-ameter of approximately 3 inches would be suitable, with the flow rate the fluid pump is able to deliver. The rest of the pipe dimensions vary between 1 and 3.5 inches and were
adjusted according to the dimension of the test pipe section and the dimensions of the dif-ferent sensors, valves, and additional equipment of the loop.
The dimension of the test pipe was found using MATLAB functiontest pipe dimension.m in Appendix A.5. It was assumed that a typical flow line diameter is 16” and that approx-imately 70 % of the pipe is filled with drilling fluid. A typical offshore flow rate of 3000 lpm gave a flow velocity of 0.55 m/s. The chosen 76.1 mm (3 in) OD pipe with approx-imately 75 % of the pipe filled with liquid will give a liquid flow rate of 101 lpm, which is in the range of the fluid pump, when cooling is added. Assuming a flow rate factor of 1 between gas and liquid, the gas flow rate would be 34 lpm, which is also within the range of the gas controller.
The test pipe section is made of stainless steel pipe. Key specifications can be found in Table 17.10. Stainless steel was chosen for the test pipe due to the acoustic properties of steel, as steel material is better for conducting acoustic wave signals than plastic material.
The decision was made to optimize the ClampOn readings. Offshore flow lines are often made of steel and choosing stainless steel for the test section makes the results obtained in the project more relatable to offshore conditions. Plastic connections will be used on both sides of the test pipe to reduce background vibrations.
Table 17.10– Key specifications for the stainless steel pipe [65].
Parameter Value
The pipes leading into and out of the test pipe section and the pipes making up the venturi meter is made of transparent PVC plastic. This is chosen to have the possibility to get a visual of the flow inside the pipes during experiments, for instance to see if the flow looks laminar or turbulent. The plastic pipes are cheaper and less heavy than the steel pipe used in the test section. Another reason for including the PVC pipes close to the ClampOn sensor is to reduce background noise, as plastic material has a reduced ability to conduct acoustic waves compared to steel. The small diameter pipe is used to create the restriction in the venturi meter. The vendor of the transparent PVC pipe is GPA and key specifications can be found inTable 17.11. The pressure ratings of the plastic pipes, 16 bar and 10 bar, are sufficient for the flow loop during the project as the experiments will be conducted at atmospheric pressures.
Table 17.11– Key specifications for the transparent PVC pipes [66].
The rest of the flow loop pipe is made of PVC plastic pipes that are not transparent, as there is no particular interest in observing the flow in the remaining part of the flow loop.
These PVC pipes are delivered by Ahlsell, and they are cheaper than the transparent PVC pipes from GPA. Many of the advantages of the transparent PVC pipes also applies to the Ahlsell PVC pipes, such as being less heavy than steel and the reduced background noise.
The pipes have a pressure rating of 10 bar, which is sufficient during the project as the experiments will be conducted at atmospheric pressures. The key specifications for the pipes can be found inTable 17.12.
Table 17.12– Key specifications for the PVC pipes [67].
A solenoid will be mounted on the test pipe section to hit the test pipe regularly. The purpose is to see if acoustic signals recorded on the ClampOn sensor can be correlated to the flow conditions in the pipe. The principle can be compared to tapping on a glass filled with different levels of water and hearing different sounds. The working principle behind the solenoid is converting electrical energy into kinetic energy. The solenoid contracts when electric current is applied due to electromagnetism and is pushed back to the original position by a spring force when the electric current is turned off [68].
17.11 Tanks
The flow loop has two tanks included in the design. The idea is to run the experiments using only one of the tanks. When introducing cuttings to the flow, it will be done by pouring cuttings into the tank and then circulating for a while to get the cuttings evenly distributed in the flow. To make sure the cuttings are mixed into the fluid in the tank, and not accumulated at the bottom, a mixer will be placed in the tank. This is to ensure that cuttings are fed to the pump. The remaining tank will contain clean water and is included for cleaning purposes. After finishing experiments with cuttings a screen will be used to remove the cuttings, before the clean water tank is connected to flush the system. The size of the tanks is 200 L and both tanks have an inlet at the top and an outlet at the bottom.
17.12 Valves
There are several valves in the flow loop for different purposes. One type of vales are PVC ball valves delivered by Ahlsell. They are used upstream and downstream of the two tanks
to control which tank is included in the flow loop. There is also one downstream of the flow meter that will have a choke function to get a better measurement on the flow meter.
Another one is found downstream of the venturi meter and can be used to increase the pressure in the loop. Key specifications for these valves can be found inTable 17.13.
Table 17.13– Key specifications for the PVC ball valves [69].
Diameter Parameter Value
A PVC one-way valve is mounted downstream of the PVC ball valve after the Coriolis.
The purpose is to prevent influx of air to the Coriolis and fluid pump. The valve can take pressures up to 16 bar. Key specifications can be found inTable 17.14
Table 17.14– Key specifications for the PVC one-way valve [70].
Parameter Value
Vendor GPA
Product number CVIU-E-63
Material PVC
Max. pressure 16 bar
A brass ball valve is mounted downstream of the gas control to function as a choke. The valve is more robust and can take pressures up to 32 bar, which is a safety measure as it is mounted close to the gas controller. Key specifications can be found inTable 17.15 A brass one-way valve is mounted downstream of the brass ball valve. The purpose is to prevent influx of liquids to the gas controller. The valve can take pressures up to 20 bar, which is a safety measure as it is mounted close to the gas controller. Key specifications can be found inTable 17.16
Table 17.15– Key specifications for the brass ball valve [71].
Parameter Value
Vendor Ahlsell
Product number 5665004
Material Brass
Max. pressure 32 bar
Table 17.16– Key specifications for the brass one-way valve [72].
Parameter Value
Vendor Ahlsell
Product number 5546213
Material Brass
Max. pressure 20 bar
A PVC ventilation valve is mounted downstream of the long, elevated pipe section after the venturi meter. The purpose is to allow for air ventilation to avoid air in the fluid tanks.
The valve can take pressures up to 16 bar. Key specifications can be found inTable 17.17 Table 17.17– Key specifications for the PVC ventilation valve [73].
Parameter Value
Vendor GPA
Product number VAIV063
Material PVC
Max. pressure 16 bar
17.13 Stand
A stand to support the flow loop will be built. The parts are ordered from AluFlex and E.A.
Smith. The plan is to mount rails to allow for a flexible system. This way alterations can be made without extensive work.Fig. 17.7shows a simple schematic of the stand set-up.
Rails are placed on the floor with large poles mounted on top. The poles can be moved parallel to the rail. Bars are mounted on each pole and can be adjusted in the vertical plane.
The stand can be mounted to the wall for support and stabilization.
Fig. 17.7– Schematic of set-up for stand.
17.14 Restriction
The restriction will be built by gluing a plate inside a pipe. The idea is to disturb the flow in order to create turbulent flow. The orientation of the plate is chosen to avoid cuttings accumulation. The plate intrudes from the side and in the direction of the flow, as can be seen inFig. 17.8. In the figure, the plate is glued to the side of the pipe that is furthest away from the paper plane and points diagonally towards the opposite side of the pipe.
The restriction must be mounted close to the test pipe section in order for the flow to stay turbulent through the test pipe section.
Fig. 17.8– Schematic of restriction.
17.15 Cuttings
The size of the cuttings is decided based on the screen dimensions. In offshore drilling operations, the diameter of the small cuttings separated at the shakers can typically be 0.5 millimeter. To downscale by pipe size ratio this would require using very fine cuttings par-ticles in the flow loop. To be able to remove the cuttings efficiently it is desired to avoid too fine particles. The cuttings will therefore be sand particles of type Sponesand with average diameter of 2.5 millimeters. Key specifications of the Sponesand can be found in Table 17.18.
The amounts of cuttings to be added are calculated based on offshore drilling conditions, by MATLAB functioncuttings concentration.min Appendix A.6. By choosing a typical ROP of 30 m/hr for an 8.5 in hole, a cuttings rate of 18.3 lpm was found. Combining this
Table 17.18– Key specifications for Sponesand [74].
Parameter Value
Vendor Sibelco Nordic AB
Average diameter 2.5 mm Diameter range 2-3.5 mm
Shape Angular to round
Bulk density 1500 kg/m3 Chemical formula SiO2
with a typical flow rate of 2000 lpm for the hole section gives a cuttings concentration of 9.1 % in the flow. The concentration of cuttings in the return flow will vary during a drilling operation but the calculations can be used as an estimation. The cuttings concentration combined with the calculated volume of the flow loop will be used to compute the volume of cuttings to be added.
17.16 Screen
A type of screen will be built. The purpose is to remove the cuttings from the fluid in the flow loop, simulating a shale shaker. It will be placed before the inlet of the tank.
A cylinder containing a sieve is the planned design. The openings in the sieve must be smaller than the size of the cuttings to allow for cuttings accumulation. At the same time, the openings should not be too small, as it may prevent passage of water. If the water can not pass through the screen it can lead to the screens flowing over, resulting in cuttings ending up in the tank.
17.17 LabVIEW
The engineering software LabVIEW will be used in the project. All the instrumentation in the flow loop will be connected to LabVIEW. In LabVIEW, the instrument parameters can be controlled, and sensor measurements are collected and processed. A graphical representation of the flow loop will be programmed, simulating a flowchart. Data analysis algorithms will be created to process the sensor measurements. The software also offers a debugging function [75].