LORD Corporation Downhole Test Simulator Feasbility Study
Matthew Biron1, Daniel Bowers1, Nicholas Fewell1, Hyungsuk Kang1, Abigail Tremont1, Jason Whyte1, Sam
Zimmerman1
1
Rochester Institute of Technology
Proper testing of vibration isolators and shock dampers used in the downhole drillling industry before the product is placed into
production is scarse. Creation of an in-house testing facility for downhole drilling vibration isolators that would resemble the
environment downhole would give any company a competitive advantage in the field. This project focuses on the research,
analyses, simulations, and small-scale prototypes that were completed to determine the feasibility of a testing facility for
downhole vibration isolators and shock dampers. To achieve the project deliverables a complete feasibility study was completed
along with 3D models of the system. The results of the designed tests concluded that the creation of a in-house testing facility
could be feasible with several considerations for improvements.
I.
BACKGROUND
In the Oil and Gas industry, it is vital to ensure that the
tooling used downhole can withstand the environment deep
beneath the Earth. The Axial Isolators that LORD Corporation
designs and manufactures are crucial to protecting downhole
tooling from axial and lateral shock and vibration. Currently,
LORD has no standard practice to test their vibration isolators
before they enter the field. Data collection and failure modes
are determined after their product has been used in real-time
production.
The intention of this project is to determine if LORD has the
capabilities to create an in-house testing facility for their
vibration isolators. Particularly, in determining the feasibility
of this facility the focus on the design will be on the pressure
vessel in which the testing will occur along with the axial and
lateral shock and vibration application, and mud flow process
throughout the vessel. By doing this, LORD will have an
advantage in the Oil and Gas Industry by providing their
customers with a better guarantee that their part will survive in
its environment.
Specifically, the approach taken to prove the feasibility of
the test simulator was to conduct several mathematical
analyses, simulations, and small-scale prototype tests. These
tests were designed and completed to prove that each subsystem
can function as a part of the entire system. The physical
prototypes were scaled down to ensure that they could be
properly tested.
Along with technically validating each subsystem, research
was conducted to determine a bill of materials for the testing
vessel. From this research, a thorough cost analysis was
created. Future risks and recommendations were considered as
well.
II.
SYSTEM OVERVIEW
For design purposes, this complex system was broken into
four subsections which include the mud flow, axial and lateral
forces, the torsional force, and the structural systems. Since
these have been designed separately they can each function
independently from each other as well as be combined to fulfil
the specified requirements. Each subsystem is tied together
using a centralized control system.
A. Overall System Overview
The system imparts static and dynamic forces to a test article
located inside a pressure vessel. Through the pressure vessel
flows drilling mud at pressures up to 20ksi and temperatures up
to 350ºF. The forces can be applied in the torsional, lateral, and
axial direction or in any combination of these. A cutaway of the
pressure vessel design is shown below, in Figure 1.
FIGURE 1.
PRESSURE VESSEL DESIGN
An overall system design can be seen below in Figure 2. In
general, these processes are controlled through feedback loops
to ensure appropriate forces and conditions are being generated.
Furthermore, it is designed such that any non-linear forces are
translated to the pressure vessel before they arrive at the
axial/lateral seals. In the same way the torsional side is braced
against axial and lateral motion so as to minimize the
undesirable forces seen at the rotary seal. It should also be noted
that, as designed, the system is sufficient to flow mud around
and through a test article.
FIGURE 2.
OVERALL SYSTEM DESIGN
While designing the pressure vessel and overall system, the
team had several engineering and customer requirements to
consider. These considerations are outlined below in Table 1.
TABLE 1.
SYSTEM CAPABILITES
Engineering Requirement
CR Value
Adjustable Temperature (F)
0-350
Adjustable Pressure (ksi)
0-20
Mud Flow Rate (GPM)
350-800
Mud Temperature (F)
125-250
Static Axial Load (lbf)
4-1000
Static Lateral Load (lbf)
4-1000
Static Torsional Load (kip-ft)
0-50
Dynamic Vibration Load (g)
0-50
Vibration Frequency (Hz)
1-350
Dynamic Shock (g)
Dynamic Shock Duration (ms)
200-1000
.5-20
B. Axial-Lateral Force Subsystem
1) Axial-Lateral Force Application
The axial and lateral dynamic forces are being applied to our
system via two 55,000 pound shakers. These shakers were
quoted from the Unholtz Dickie Corporation (UDC), and can
apply up to 55,000 pounds in both shock and sinusoidal
vibration, along with the capability to handle high static-load
situations. Much of the setup, mounting, and power usage design
are handled by UDC, and they have offered to help design
system mounts for this application. Each shaker has a footprint
of 13’8”x7’7” and weighs 50,000 pounds.
Mounted to each of the shakers will be a Moog ball-screw
actuator. These ball screw actuators will handle the static forces
as well as any ultra-low frequency vibrations specified
(vibrations on the order of 1 Hz or lower). It was confirmed by
Moog that these actuators can handle the vibration loads
transmitted through them, which is the primary reason these
actuators were chosen over a hydraulic actuator. Each actuator
has a continuous stall force of 1,971 pounds (peak stall force of
4,985 pounds) and a maximum shaft speed of 8.1 inches per
second. These actuators will be mounted to the slip tables of the
UDC shakers using mounts designed by UDC.
2) Axial-Lateral Transfer Linkage
In order to meet Engineering Requirement which requires
both a static axial and lateral load, we designed a system to
transfer two axial forces into an axial force and a lateral force.
This was done to prevent excessive shear forces on the pressure
vessel that would have resulted from directly applying a lateral
force to the system. The linkage is designed with a 3:4
axial/lateral force ratio, so that the amplitude of the lateral
displacement is amplified. This also means that the force applied
is attenuated by the same ratio, which must be taken into
account. Based on a pair of input forces F1 and F2, the forces
transmitted through our designed linkage are as follows:
(a)
FA = F1 + F2
3
(b)
FL = (F1 - F2 )
4
where A is the force applied in the axial direction and L is the
force applied in the lateral direction. Using these two equations,
it is possible to generate any axial and lateral force through a
well-designed combination of input forces.
C. Torsional Force Subsystem
The torsional subsystem exists to fulfil the requirement of
applying dynamic torsional load at up to 50g and a static
torsional load of up to 50 kip-ft. In addition, the torsional side
must be robust to the linear and axial forces which are
transmitted through the test article. The design of the torsional
system must also take into account the damping created by the
mud flow.
1) Torsional Force Transfer Piece
The torsional transfer piece is used to reduce the number of
holes and subsequent seals needed for the design. The transfer
piece is a steel rod which is attached to a casted junction piece.
The transfer rod simply allows for the application of the static
and dynamic forces external to the pressure vessel and inner
pipe. This transfer piece is 6” in diameter is made from ASTM
A108 low carbon steel.
2) Torsional Force Application
The torsional force is applied by two MOOG electric linear
actuators with a stroke length of 12in. These two actuators are
attached to a CAM transfer piece which is permanently fixed to
a steel transfer piece. The test article is to be threaded into a
casted junction piece which is threaded onto the transfer bar.
The junction is designed to allow mud flow passing through the
test article to exit and flow out of the tank. The linear actuators
in this design have been specified by MOOG to be able to handle
the dynamic loads passing through the system.
3) Dynamic Load Application
The dynamic load is applied by high force shaker supplied
by Unholtz Dickie Corporation which is capable of generating
55,000lbs of vibration.
The dynamic load is applied
independent from the static load through the use of a high force
hydraulic clamp supplied by Planet Products. This clamp is
located outside of the pressure vessel and thus, in a region
where the axial and lateral vibrations are negligible. Thus, the
only vibration is orthogonal to the hydraulic clamping force and
will not propagate through the hydraulic system. The control
of this system is such that the static force is realized before the
clamp is closed. In this manner any deflection caused by the
torsional static force will not distort the application of the
dynamic load. This design is further analyzed in following
sections.
4) Torsional Force Considerations
Firstly, the torsional system must be robust to the axial and
lateral loads being transmitted through the test article. To
accomplish this the transfer piece is braced internally to the wall
of the pressure vessel. This will prevent any axial distortion
from being transmitted to the seals or to the CAM system.
Next, the transfer piece is externally braced at the end against
lateral forces. This will prevent any lateral motion from wearing
on the rotary bearings or from bending the actuators.
5) Torsional Control Scheme
The torsional system uses a feedback system to achieve the
forces specified. There are accelerometers to measure the input
dynamic forces. The tri-axial data is fed back to the controller
supplied with the high force shaker. In this way the shaker can
increase inputs to meet the specified conditions. The static
forces work in a very similar manner using a load cell. In the
case of the static forces the data from the load cell is fed back
to the MOOG controller. There is an overall control system
which keeps the correct order of operation. First, the static
force must be realized so any distortion of the UUT will occur.
After this the hydraulic clamp is closed and the dynamic force
can be applied. At the end of the test this must be repeated in
the opposite order to ensure no stresses are transferred to the
dynamic system. For safety all forces are monitored to ensure
the magnitude does not change by more than 15%. If any force
changes by more than 15% it is assumed that a failure has
occurred somewhere in the system and it automatically goes
into emergency shutoff.
D. Mud Flow Subsystem
1) Mud Flow Application
The mud flow system is a closed flow loop design utilizing
diesel powered hydraulic fracking pumps as the power source to
move the flow. The mud begins in a 2100-gallon storage tank
where it is heated to the desired operating temperature, as
specified in the engineering requirements, using a Chromalox
Large Tank Immersion Heater. Whilst in the tank the mud is
kept in motion using a GN Solid Controls Agitator to prevent
clumping or settling. A boost pump is used to pressurize and
move fluid such that the main pumping system can draw fluid.
The main pumping system includes 7 total fracking pumps, with
6 pumps being in use and one pump used for backup. Each pump
is capable of meeting the 20,000 psi pressure requirement as
stated in the engineering requirements. The 6-pump
configuration will allow for the volumetric flow rate
requirement of 350-800 GPM to be met as well. Each pump in
the system will have its own cooling tower to maintain proper
performance. At the maximum operating condition the pumping
system will be utilizing 12,500 BHP and 714 gal/hr of diesel
fuel. The overall footprint for the pumping system is 70’ x 60’.
The pumping system would be purchased as a complete
package from National Oilwell Varco’s Pressure Pumping
Equipment group.
2) Mud Purging Process
After running tests it will be imperative that the flow loop is
flushed clean of any residual mud. This residual mud if not
cleared from the system could eventually cause problems with
clogging flow paths as well as unwanted debris in crucial test
areas. To combat this problem a mud “purging” process was
developed. This process adds an additional storage tank for
water that is integrated into the main pumping system by way
of two switching valves, for outlet and return flow lines. This
clean water will then be pumped through the system to cleanse
it of any remaining mud. The water tank will then have to be
periodically emptied and cleaned in order to maintain the water
cleanliness.
3) Mud Flow Control System
In order to control the mud requirements, pressure sensors,
heat sensors, and flow sensors were required to be included in
the design. The heating has the simplest form of control. The
design uses at minimum two thermocouples to measure the heat
of the mud. More may be needed in the tank to ensure that the
heat is even while the mud is inside of the tank. The specific
thermocouple utilized is called RT02 from pyromation. It has a
sheath to protect from external wear such as mud. The sensor is
able to withstand up to 200°C. One thermocouple would be
located right before the pipes enter the pressure vessel and the
rest would be located in the tank. If the pipe thermocouple
temperature was too low then the tank can be heated up further
to increase the output temperature. The tank thermocouples
would then be there to ensure that the tanks temperature don’t
reach unwanted values and that the heat is distributed evenly
throughout the mud.
The flow and pressure control of the mud is slightly more
complicated due to their dependency on each other. Both sensors
are located next to each other right before the pipes enter the
pressure vessel. The pressure sensor is a Hammer Union
Pressure Sensor 434 which is already used in the oil and gas
industry and supports up to 20k psi. The flow sensor is Turbine
Flow Meter – FT Series from Flow Technology. The sensor is
able support the pressure, flow, and temperature of the mud. A
more specific control scheme will need to be devised for precise
control. The basis would be that the pressure sensor helps
determine how much power is supplied to each mud motor and
the flow sensor helps determine how many motors should be on.
Because of the dependency between the pressure and flow rate
with the more, the control scheme may be more complicated for
correct outputs. This control scheme was not specified as it was
beyond the scope of this project and of what would be useful in
proving the feasibility of the design.
E. Pressure Vessel Subsystem
1) Pressure Vessel Overview
In order to contain the 20,000-psi pressure acting on the
unit under test, we designed a pressure vessel capable of
containing this load. The cylindrical pressure vessel will have
a 28-inch inner diameter and be 12 feet long internally. In
order to withstand the pressure, the entire pressure vessel
needs to be made from 8-inch thick alloy steel. Each end will
consist of a gasketed hatch in order to access the interior of the
container. These gaskets will have holes for the load
application shafts (2 on one side, 1 on the other side) with the
appropriate bearings and seals. Each end will also have a drip
collector, which have been designed to collect any mud that
leaks through the seals during operation. These collectors will
need to be routinely checked and emptied, and can be used as
early indicators of seal failure (assuming the failure is not
catastrophic).
Inside the pressure vessel, there is an inner sacrificial low
carbon steel pipe designed to prevent wear and tear on the
external pressure vessel. The interior pipe is 18 inches in
diameter on the axial/lateral load side, and steps down to 10
inches in diameter before reaching the unit under test. The ten
inch section is completely removeable and is made to be
cycled often due to wear and tear.
The pressure vessel has five permanent holes: two mud
inlets, the mud outlet, the heated air inlet, and the pressurized
air inlet/outlet. The mud inlets enter the pressure vessel at a 30
degree angle to improve flow and prevent excess turbulence
within the system. They pass through the outer wall of the
pressure vessel and connect with the inner steel pipe. The mud
outlet is perpendicular to the pressure vessel, and must be
located at the lowest point in the system for drainage
purposes. The mud outlet connects with the inner pipe and
passes through the pressure vessel near the torsional side. The
heated air inlet connects to the air circulator and heat
exchanger, and passes through the pressure vessel to connect
with the interior pipe near where the unit under test sits. This
is to ensure that as much heat gets to the test article as possible
before the air cools. This air is unpressurized and simply
generates an initial temperature condition for the test. The air
will leave the pressure vessel through the mud outlet, which
vents into an open container which is capable of handling
extra air. The pressurized air inlet/outlet is a valve that
connects the air compressor to the pressure vessel. This valve
allows air in and out, and is used to pressurize the system to
20,000 psi and to release the air before opening the pressure
vessel.
The interior of the pressure vessel will have steel support
structures to hold up the interior pipe. The interior pipe will
also be bolted into place with gaskets on either end, ensuring
that no mud leaks from the interior pipe into the main portion
of the pressure vessel.
2) Pressure Vessel Control System
In order to control the pressure correctly to create a zero
pressure gradient across the inner pipe the design uses
information from the mud system and pressure sensors within
the pressure vessel itself. The pressure vessel sensors are Series
GT16XX Industrial Pressure Transducers and Pressure
Transmitters which are supplied by LORD. The sensors will be
able to withstand up to 40k PSI. The control scheme itself would
be rather simple. Based on the mud system pressure information,
the air pump will be brought up to that pressure and the GT16xx
will be used for direct feedback of the pressure seen. The current
design has at minimum two of sensors on both sides of the vessel
but more can be added to ensure uniform pressurization. HVAC
Subsystem
3) HVAC System Overview
The Heating, Ventilation, and Air Conditioning (HVAC)
system was designed solely to support the first engineering
requirement. The temperature required for the system had to
range from 0°F to 350°F. To simplify this the temperature
ranges were separated to be from 0°F to 70°F and 70°F to 350°F
where 70°F is the standard room temperature. This was done in
order to incorporate current heating and cooling units easier into
the design. The HVAC is then split into two different sections in
order to achieve the requirement. The heating unit was
benchmarked and the one chosen for the design was the CAB611 from Chromolox. The CAB-611 supports up to 440°F and
includes a blower and duct to create air currents. The heater is
then connected to a valve through simple ducting. The valve is
a hydraulic controlled drilling type choke valve from Cameron.
The valve is connected to the pressure vessel and has a channel
directly to the testing tube in order to reach the part. The drilling
choke is necessary because once the test runs there will be
marginal pressure on one side and the pressurized mud on the
other so a more complex valve is needed in order to contain the
pressures correctly. With this connection, the air around the unit
under test can then be heated up to necessary conditions.
The cooling was unit was researched and, in order to cool a
larger amount of air, a custom model was needed. A custom
cooler was quoted by Xchanger Inc. The custom cooler uses
liquid nitrogen and includes a blower. The custom unit is
specified to reach the required 0°F from normal room
temperatures. The cooler is connected similarly to the heating
system through its own choke valve. With this, there is then a
path of the cooler to the unit under test.
The control unit is fairly simple due to the focus being on
heating or cooling the unit to a set point. Once that point is
reached the test will run and the requirement will be fulfilled.
The connections leading to the valve will have a temperature
sensor and there will be a temperature sensor inside the testing
tube on the torsional side. Because the unit under test will be
similar to the metal attachments for the torsional end, the
temperature of the unit under test would be approximately the
same. Direct tests could be done in order to better approximate
a model for the temperature control based on the sensors
feedback. This specific design with the temperature sensor was
done in order to avoid problems with a varying unit under test
and from the mud flow affecting the sensors or wires. This
concludes how the HVAC system is set up for the design.
III.
SYSTEM VALIDATION
In order to prove the validity of the designed system to the
engineering requirements, several different kinds of tests were
run. These tests are broken down into three different categories.
Analysis tests were based on hand calculated formulas and
values. Simulation tests were done for better approximations to
the real world. Prototype tests were completed as small scale
tests of major components. The tests also reflect how much risk
there was in each section. For example the heating was
straightforward so only analysis tests were done but the axial
and lateral had all three forms of tests done in order to prove its
design throughout the project.
Formal test plans were created to test each of the engineering
requirements. All results from the test plans were then examined
by a subject matter expert to verify the outcomes. Once the
subject matter expert is okay with the process and results, the
final report for the test could then be written up. The report for
the tests include the specific actions that were taken, the raw data
of the results, who the subject matter expert was that reviewed
the test, and a final summary of how the results pertain to the
requirements. With this setup, the tests were then completed.
Below, Table 2 shows how each engineering and customer
requirement was validated.
TABLE 2.
Engineering Requirement
VALIDATION TYPES
CR Value
Test Type
Adjustable Temperature (F)
0-350
Analysis
Adjustable Pressure (ksi)
0-20
Analysis, Simulation
Mud Flow Rate (GPM)
350-800
Analysis, Simulation
Mud Temperature (F)
125-250
Static Axial Load (lbf)
4-1000
Static Lateral Load (lbf)
4-1000
Static Torsional Load (kip-ft)
0-50
Dynamic Vibration Load (g)
0-50
Vibration Frequency (Hz)
1-350
Dynamic Shock (g)
Dynamic Shock Duration (ms)
be run on the full test rig to determine the effects of the mud on
the vibration. The following prototype setup is shown below in
Figure 3.
200-1000
.5-20
Analysis, Simulation
Analysis, Simulation,
Prototype
Analysis, Simulation,
Prototype
Analysis, Simulation,
Prototype
Analysis, Simulation,
Prototype
Analysis, Simulation,
Prototype
Analysis, Simulation,
Prototype
Analysis, Simulation,
Prototype
FIGURE 3.
AXIAL-LATERAL PROTOTYPE SETUP
B. Torsional Load and Vibration Scaled Prototype
In order to test transmission of vibration and load, we
designed and ran a small scale prototype test of the torsional load
and vibration. The prototype system maintained the same aspect
ratio as the proposed final design, and had significantly reduced
loads to prevent mechanical failure and reduce the cost of
required equipment and structure. The goal of the prototype
were to determine if our system was capable of generating
torsional load and vibration independently to the unit under test.
We were able to produce torsional load from an air spring, and
we were able to produce torsional vibration from an
electromagnetic shaker. Through the test we determined that the
natural frequency of the system was consistent with various
torsional load and vibration conditions, which means the
stiffness of the system was consistent during the test. The
prototype setup is shown below in Figures 4 and 5.
There were two major prototype tests that were
designed and conducted to prove the feasibility of the axial and
lateral forces and the torsional forces. They are described below:
A. Axial-Lateral Linkage Small Scale Prototype
In order to test the effects of water on our vibration transfer
system, we designed and ran a small scale prototype test of the
proposed linkage. The prototype system maintained the same
aspect ratio as the proposed final design, and had significantly
reduced loads to prevent mechanical failure during the test. The
goals of the prototype were to determine if our system was
capable of generating axial motion and lateral motion
independently and to determine the damping effect of the water
on the system as a whole. We were able to produce pure axial
motion, and we were able to produce significant lateral motion
with only a small amount of axial vibration. This is likely due
to the geometry of the system and may not be avoidable.
Through the test we discovered that the water had a different
damping effect on each direction of motion depending on which
direction had the larger cross-sectional area. Since the lateral
direction was more aerodynamic, it had a significantly lower
damping factor than the axial direction. This will change
significantly in the final product, so additional tests will need to
.
FIGURE 4.
TORSIONAL PROTOTYPE SETUP
operational costs purely for the running of the test simulator. It
should be noted that no amounts provided here include building
costs, or the cost associated with housing this test apparatus.
FIGURE 5.
TORSIONAL PROTOTYPE SETUP
B. BOM Review
The BOM is broken into four sections including the mud,
loads and vibration, structural, and controls subsystems. For the
mud subsystem the largest contributor to the cost are the mud
pumps. Here it may be possible to incrementally purchase the
expensive pumps. Before taking this approach one must
thoroughly study the relationship between the number of pumps
present and the pressure and flow attainable. Also, included in
the mud section are the holding tanks for the mud and flush
water as well as the immersion heater necessary to bring the mud
up to temperature.
Subsystem
IV.
RESULTS
At the conclusion of the analyses, simulations and prototypes
it was determined that a majority of the engineering and
customer requirements could be met. The following table
shows what values that the team was able to determine that the
system could meet.
TABLE 2.
Engineering Requirement
ACTUAL VALUES
CR Value
Actual Value
Adjustable Temperature (F)
0-350
0-275
Adjustable Pressure (ksi)
0-20
0-22
Mud Flow Rate (GPM)
350-800
350-800
Mud Temperature (F)
125-250
90-275
Static Axial Load (lbf)
4-1000
4-1000
Static Lateral Load (lbf)
4-1000
4-1250
Static Torsional Load (kip-ft)
0-50
0-60
Dynamic Vibration Load (g)
0-50
0-70
Vibration Frequency (Hz)
1-350
25-300
200-1000
0-140
.5-20
.1-80
Dynamic Shock (g)
Dynamic Shock Duration (ms)
Along with validating the engineering and customer
requirements for the feasibility study, the team created final 3D
models of the pressure vessel and the overall system which
were turned over to the customer, LORD.
V.
COST ANALYSIS
A. Cost Overview
A bill of materials (BOM) containing the pieces of the
simulator which were deemed to be most expensive can be
found on EDGE under the “Full System BOM” link in the work
breakdown structure. These components come to a total of
$6,000,000 which is estimated through both quotes and rough
order of magnitude (ROM) requests made to viable
manufacturers. Also included in this report is an estimate of
Loads/Vibrations
Mud
Structural
Controls
Acquisition Cost
Total
Total Cost
3,097,799.70
9,180,575.00
2,224,209.02
35,950.08
1,453,853.38
15,992,387.18
Under the loads and vibrations category the largest
contributors are the shakers necessary to reach the acceleration
requirement while the system is under the maximum static load.
Following this, the next largest cost at $40,000 a piece are the
linear actuators needed to create the lateral and axial loads.
These actuators were directly quoted from MOOG with the
understanding that they would probably be customized when
actually purchased. There aren’t any components here that
present a large risk of hidden cost increases.
The most difficult category to handle is the structural
category. With this system design the largest number of custom
components fall into this category. The pressure vessel is the
most important piece as far as safety is concerned and it is also
the part that requires the most customization. With a ROM price
of $1,300,000 the pressure vessel represents a large risk of cost
volatility as it is difficult to predict the cost of customization.
The next largest cost contributor is the inner pipe. This is the
combination of the “inner pipe” and “inner pipe junction.”
Again this piece will require a one off custom casting to produce
the junction piece. At $600,000 the inner pipe is the piece that
is meant to take the brunt of the wear and will need to be
replaced. It may be desirable to acquire multiple diameter inner
pipes and junction pieces in order to test multiple parts. Only
the cost of purchasing a single inner pipe and junction piece is
considered in the BOM. Included in the BOM is an estimate for
the cost of pipe necessary to get the mud from the pumps to the
pressure vessel. Clearly this is very dependent on the layout of
the facility and how close the pumps can be located with respect
to the pressure vessel. With this in mind the rough layout we
came up with used less than the 500ft quoted in the BOM.
Another noticeable cost comes from the air compressor used to
achieve the 20ksi air pressure. This should not present much
risk for increase as it was a quote from Hydropac. It is important
to point out that the cost of a lubrication system for the seals is
not included in the BOM and will be critical to the life and
proper operation of the seals. The final part that may be difficult
to source are the bearings required to prevent force from being
transferred to the seals. Included in the BOM is a ROM cost for
these, but it is likely that these will be custom bearings due to
the size and force they will experience. The last thing not
included in this BOM is any structural supports for the pressure
vessel itself. Since all forces generated are transferred to the
pressure vessel before getting to the seals it may be necessary to
brace the pressure vessel to transfer forces to an external support
system. With all of this in mind the structural category poses
the most risk for budget increases.
The final category contains the costs for controls. This cost
is closely tied to the cost of controlling the MOOG actuators and
the shakers. All of the sensors are on the order of $1,000 and
were specifically designed to be robust to vibration and the
abrasive mud. None of the sensors require customization which
makes them simple to acquire and replace. There are no
surprises in this category and very little risk for cost increases.
The cost of housing the testing rig along with the
infrastructure for supplying electricity to the system are not
estimated in this study. It should be expected that the
infrastructure necessary to support the entire system will be
extensive. This stems partially from the space necessary for the
mud and water tanks along with the large space taken by the
pumps. For the electricity it is probable that the system will
require infrastructure on the order of dedicated transformers and
should not require anything as extreme as a dedicated substation.
C. Operational Cost Review
Two estimates are provided for operational cost which
includes running the simulator for half of the year and an
estimate for running the simulator for half the business hours in
a year. The cost associated with operators was estimated based
on the need for 4 operators for setting up the system and 1
operator while the system is running. Furthermore, it was
estimated that setting up the system would take 20% of the time
and it would run with a single operator for the remainder. It can
be seen that the estimated cost per hour of an operator is $100.
The largest contributor to operational cost is the price of diesel
for the pumps. This estimation is based on running at full
capacity the entire which would require the use of 6 pumps.
These 6 pumps would go through 714 gallons per hour which
at the current diesel wholesale price would end up costing
around $1,100 per hour. Both the cost of water and electricity
are relatively cheap when compared to the other operational
costs and will only change incrementally depending on usage.
It is prudent now to address the cost associated with the
maintenance of the simulator. At this point in time it would be
an ambitious task to attempt the estimation of the lifetime with
regard to almost all components. It can be said that the parts
most probable to need frequent replacing are the seals. Each
time the seals are replaced it will cost $7,135 in parts alone. It
is also foreseeable that the pipes will need biannual cleaning
which is in addition to the flushing which is to be performed
after every test. The pumps will need maintenance on par with
usual diesel engine care which is specified by the manufacturer
and is dependent on the exact model purchased. It is known
that the design sacrifices the inner pipe to preserve the more
costly pressure vessel. It is unknown how fast this inner pipe
will deteriorate.
D. Budget Alterations
It is possible to make incremental alterations to the design
and reduce the overall cost. In doing this, one must first attain
an end goal and keep this in focus. For example, the pressure
requirement drives a major portion of the cost in both the
structural and mud subsystems. One might correctly observe
that reducing this requirement in the short term would reduce
the cost associated with the pumps and the cost associated with
the pressure vessel. The pumps could then be scaled up over
time making the cost incremental and built into the budget over
several years. This is not the case with the pressure vessel
though. Every time the pressure capability is increased the
pressure vessel would have to be entirely rebuilt. In this way,
the end goal must be the beginning of any discussion on cost
reduction. With this being said, the two largest contributors to
the overall cost are the pressure and dynamic load requirements.
To this point it may be possible to decouple the static and
dynamic loads which may results in a size reduction for the
shakers. It is also safe to say that the flow and pressure
requirements are driving the operational cost through the
consumption of diesel. In conclusion, there are extensive
possibilities for system redesign driven by the desire for cost
reduction.
VI.
POTENTIAL RISKS
Several risks were identified throughout the system design
and validation processes. By conducting the analyses,
simulations, and prototype tests possible risks were mitigated
based on the results from each test. The following section will
describe in detail the risks that were still prominent even after
thorough testing and research.
A. Sealing Risks
Major risks with the system design pertain to the sealing that
will be used in the pressure vessel design. It is possible that the
sealing will break down to due actuation, fatigue, abrasion, or
excess applied loads. These risks were unable to be mitigated
through proper validation testing since the proper resources
were not available to team. Also, the team’s budget does not
allow for testing of the seals at an off-site testing facility. It is
the team’s suggestion for LORD to follow through with the
testing of the sealing options at an off-site testing facility.
B. Subsystem Integration Risks
The team designed all of the analyses, simulations, and
prototypes with the intention for each subsystem to properly
function with each other. Although proper testing was
conducted, the team did not have the opportunity to run an
overall small scaled test of the entire system. It is still a potential
risk that the subsystems will not properly function with each
other but it is not likely.
C. Heating Stress Risks
Thermal shock on the seals has the potential for premature
failure. This should be properly tested before creating a final
design.
VII. FUTURE RECOMMENDATIONS
This project is not finalized by any means, and we recommend
these follow-up projects before the system is built and
finished:
1. Validation and Life Span Testing for Seals – The seals
have been quoted to be potentially feasible, but they
should definitely be fully tested before installation.
2. Torsional Load Simulation – This simulation was not
reasonable for undergraduate students, but it may be
feasible to hire a team of graduate students to run this
simulation.
3. System Maintenance Testing – Testing should be done
on individual parts to determine a full maintenance
plan.
4. Reduced Cost Design – Our design is specified to meet
as many of the original engineering requirements as
possible. It may be possible to significantly reduce
cost by relaxing some of the engineering requirements.
5. Improved Functionality Design – Lord initially
requested multiple pieces of functionality that did not
make the final design, including hypotrochoidal
vibration, rotating the entire system to simulate
vertical and horizontal drilling, and a mud motor. Now
that there is a base design to work off of, it may be
reasonable to modify our design to achieve these new
functionality.
6. In-Depth Projects – Each individual subsystem is
reasonable to be an whole project on its own. Each
project should be tasked with fully testing the system,
improving and optimizing the design, and validating
all of the individual components.
7. Building Design – In the original PRP we were tasked
with designing the facility to house this system. Since
RIT does not currently have a civil engineering
program, this was not feasible for our group. A full
project to design the building for this will be necessary
before final build.
VIII. CONCULSIONS
After final consideration, it was determined that the creation
of a testing facility was indeed feasible. Through the use of
thorough research, analyses, simulations, and prototypes the
designs for the facility were determined. Several
recommendations were made regarding risks for the
implementation of the designs as well as future projects.