Designing better oil and gas leak testing systems
Major and minor hydrocarbon leaks from oil and gas companies result in millions of dollars in environmental damages and profit losses annually. Methane (CH4), an important component of natural gas, in addition to other fossil fuel emissions such as CO2 are monitored closely due to their combined effect on global warming, pollution, and public safety. Highly explosive gases such as hydrogen or acetylene are carefully tracked to avoid combustion reactions. Effective leak testing using Alicat devices mitigate these issues, resulting in cost savings, as well as a cleaner and safer environment.
Types of oil and gas leak tests
Traditionally, many leak testing methods have been developed to meet the specific needs of the oil and gas industry at various stages of production, transportation, and storage including:
- Manual inspections by humans or dogs
- Bubble leak tests
- Acoustic monitoring
- Gas sampling
- Soil monitoring
- Infrared cameras
- Gas and combustion sensors/detectors
- Flow or pressure monitoring
Here are the advantages to using Alicat’s devices for flow and pressure monitoring as well as gas sampling in oil and gas leak testing, including in Class 1 Div 1 and Class 1 Div 2 environments.
Designing better leak testing systems using gas sampling and monitoring
Gas sampling leak testing using gas chromatography
In many stages of oil and gas production, multivariate metering and control of operating conditions such as temperature, pressure, and flow is prevalent. In addition to controlling operating conditions, metering and monitoring also helps to detect and avoid leaks. Analyzer systems such as gas chromatography machines are both used to interpret gas compositions, ensuring that end products achieve proper regulatory and quality standards, as well as to indicate if unwanted gases are leaking into the environment via gas sampling.
However, many of these gas sampling systems rely on outdated technology such as:
- Low accuracy flow and pressure regulation
- Mechanical regulators with limited settings, metering, and data collection
- Thermal mass flow controllers that take time to turn on
- Incompatibility in Class 1 Div 1 environments
Improving gas sampling and monitoring
For more reliable and consistent gas and air monitoring, gas sampling systems which use Alicat mass flow and pressure controllers benefit from the following features:
- 24/7, continuous metering and control of pressure and flow conditions
- Multivariable measurement of temperature, volumetric mass flow, and pressure in addition to mass flow for MFCs
- Expanded communication and digital control/tuning options using either a PLC or computer
- PID and control loop tuning options to optimize gas analyzer response systems
- Class 1 Div 1 environment compatibility using IS-Series devices
- Flow control of unknown gas mixes using CODA devices
- Instantaneous start-up times
- Ability to flow different carrier gases on one device in GC
- Accuracy up to ±0.5% of reading or ±0.1% of full scale for IS-Max Class 1 Div 1 certified mass flow controllers
- Repeatability (2σ) of ±0.1% of reading + 0.02% of full scale for IS-Max Class 1 Div 1 certified mass flow controllers
- Accuracy up to ±0.25% of full scale for IS-Pro Class 1 Div 1 certified pressure controllers
- Repeatability (2σ) of 0.08% of full scale for IS-Pro Class 1 Div 1 certified pressure controllers
By using Alicat devices to control analyzers in leak testing applications, the need for manual inspections of in-line or on-line systems is reduced. With accurate, continuous, instantaneous metering and control, Alicat’s devices can help to ensure greater precision during gas chromatography by improving the accuracy and repeatability of carrier gas flow rates and pressure regulation. Moreover, by improving gas chromatography data, Alicat devices also reduce the downtime of false alarms when contaminate gas concentrations incorrectly read too high.
Designing better leak testing systems using flow and pressure regulation
Advantages of portable leak testing using Alicat flow or pressure regulation
For oil and gas leak testing such as surface casing sealing leak tests, flow and pressure regulation using portable Alicat devices such as a PB, MWB, MB, MCW, or MC offer many advantages over more rudimentary and less precise methods such as bubble tests. Some of the major advantages include:
- Actual leak rate data (or pressure decay data if using portable pressure transducers)
- Highly accurate leak rates, calibrated to your choice of specific gases
- Ease of installation and transport
- Bluetooth compatibility for easy, wireless data collection and storage (PB, MWB, and MB)
- Pressure drop as low as 0.07 PSID for MWB and MCW devices, resulting in even more accurate leak tests
- PB-Series NIST-traceable pressure accuracy to ±0.125% of full scale, for all non-corrosive gases
- MB-Series and MC-Series mass flow accuracy up to ±0.6% of reading or ±0.1% of full scale, whichever is greater
Mass flow leak testing
To perform such leak tests with portable mass flow meters, use one mass flow meter and a mechanical pressure regulator. The mechanical pressure regulator maintains a constant pressure at the device under test (DUT) while the mass flow meter provides accurate, real-time mass and volumetric flow readings. Since the DUT is subjected to a constant pressure within the closed system (such as ambient conditions), any resulting flow to maintain that constant pressure equals the DUT’s leakage rate. Alternatively, use a MWB-Series device with a portable mechanical pressure regulator to perform the same experiment with less pressure drop.
If able to use a power source, you can alternatively run a mass flow leak test using simply one mass flow controller, such as a MCW-Series or MC-Series device, running in pressure control mode while measuring the leak rate.
Pressure decay leak testing
Alternatively, use portable pressure transducers to perform pressure decay tests. A portable pressure transducer (typically a PB-Series) reads the loss in pressure from the isolated DUT over a period of time. Based on this measurement of pressure change, per test design, the leak rate either fails or passes.
Alicat creates many mass flow and pressure controllers which are specifically customized for leak testing applications.