Developing a Ballistics Pressure System Using LabVIEW and the CompactRIO Platform

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"CompactRIO allows the system to seamlessly switch between high and low samples rates and the high-speed trigger allows for synchronization of the high-speed data acquisition event with the ballistics event."

- Dan Purvis, Optimation

The Challenge:
Studying the effects of different charges on various rock formations in a simulated environment as they would occur under the earth.

The Solution:
Using NI LabVIEW software and CompactRIO hardware to develop a system that simulates the confining pressure of the earth, wellbore pressure, and pore pressure and flow to study the performance of shaped charges fired into rock samples.

Author(s):
Dan Purvis - Optimation

An Earth, Wellbore, Pore Pressure, and Flow Simulation Test System

A customer providing perforation equipment and services for the oil and gas industry required a simulated test system to study the performance of shaped charges fired into rock samples in a down-hole environment. The test system needed to accurately show the effects of different charges on various formations as they would occur under the earth.

Prior to working with NI Gold Alliance Partner Optimation, perforation testing was performed on the surface by firing charges into concrete. Due to the physical differences in concrete and formations, as well as the lack of a high-pressure environment that mimics pressures below the earth’s surface, this method of testing was inaccurate.

Optimation’s Solution

Before selecting Optimation, this customer worked with another integrator who spent eight months trying to develop a custom solution and was unsuccessful. In an 80-day time period, we designed and built a test system that simulates the confining pressure of the earth, wellbore pressure, and pore pressure and flow using a single high-pressure variable speed pump and valves. The system chamber currently runs up to 6,000 psi with an expansion capability to run at 30,000 psi.

The system is connected to the control room via Ethernet and Internet protocol (IP) cameras, allowing operators to run tests from a remote location. The industrial environment of a ballistics test system required a system with appropriate industrial ratings for flammability and a powerful shock rating. The NI CompactRIO platform met these requirements.

The User Interface

Computerized control of the system is conducted through a single user interface screen. This screen contains the ability to open and close automated valves, set pressure and flow set points, and monitor the pressure and flow values from the sensors. A location can be specified to store the data collected and charts display data over time.

Data Acquisition

This type of research required a data acquisition system with high resolution and high data rate capability. The CompactRIO system provides the necessary resolution and data rates and also allows for custom filter programming to be added in the field-programmable gate array (FPGA) section of the hardware. CompactRIO also met the client’s needs from a research perspective because the system is easily configurable and can be modified when a new test is developed.

As a shot is fired through the core sample, the user can acquire data at high and low speeds. The high-speed inputs are acquired at 100 KHz using a digital trigger or a computer start button to begin acquiring and recording for the duration of the shot. The high-speed inputs are sampled using an NI 9215 analog input module, and a trigger signal from the fire command is sent to the hardware controller to prompt the high-speed analog input acquisition. CompactRIO allows the system to seamlessly switch between high and low samples rates and the high-speed trigger allows for synchronization of the high-speed data acquisition event with the ballistics event.

With the perforation test system, operators watch process conditions for a long period of time. The process requires high accuracy at higher speeds because the user has to perform high-speed data acquisition the moment the shot is fired. CompactRIO also provides the accuracy needed for the extended process monitoring, and the high-speed capabilities deliver good shape resolution on the pressure curve off-the-shot data. To do this, sampling has to occur at a rate of 100,000 times per second.

The low-speed signals are sampled continuously at 100 Hz per channel using an NI 9203 analog input current data acquisition module, NI 9205 analog input module, or NI 9219 universal analog input module depending on whether voltage or current sampling is desired.  For critical process channels, the NI 9219 ensures data reliability because it offers an antialiasing filtering, 24-bit resolution, and up to 100 S/s per channel. Digital outputs are used to operate the air solenoids, which open and close the automated valves.

Alarming Capabilities

The system will generate an alarm if a certain pressure is exceeded. The software immediately closes all valves and turns off all pumps in the event of an alarm or emergency stop condition. A disconnection of the interface during a power outage or network failure gives control to CompactRIO, which transitions the system into a safe state.

File Storage

The system data is logged to a disk in two different files per run: a high-speed data file (shot data) and a low-speed data file (process data). Data is hardware-timed and stored with an initial time stamp. The operator sets the files used for logging data prior to running a test.  

Results

Because the earth’s crust consists of various substances from hard to porous, it is beneficial for exploration companies to know which charges work best on each formation. This simulated test system significantly impacts geologists’ ability to pinpoint within a region of a well and maximize efficiency and production. As field experts begin to understand more about the relationship between pressure and perforation using data acquired by the simulation test system, strategies will be refined to improve and revolutionize fracture stimulus and down-hole production methods.

Author Information:
Dan Purvis
Optimation

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