LOGOS- Measurement Systems
Precision Metering and LACT Units
Metering, Proving, Sampling & Analysis
An accurate and reliable measurement system is a critical part of any custody transfer activity.
“Trust But Verify”
This quote, from a politician many years ago, referred to a pending agreement between nations. In hydrocarbon custody transfer, the trust is also necessary, but the verification need is critical and of benefit to both parties. An improperly executed metering system can cause errors to the detriment of both the buyer and the seller. Logos Measurement Systems by Technics have proven to provide that verification, providing peace of mind to all invested parties, such as the owner, the operator, and the downstream buyer.
Technics carefully selects the various components of our system that provide for the highest performing metering skids in the most economical way. We are not obligated to any one manufacturer or flow measurement method. We are a systems integrator with global sourcing capabilities.
Prove It!
Whether a prover is provided as part of the metering package or if it is intended to be performed by a mobile or existing device, this has to be considered up front in the system design. Proving takes several forms, and the selection is dictated by the flow meter size, flowmeter type, but most importantly, the acceptance of that method by the parties involved and the authorities having jurisdiction.
The master meter method uses a gold standard calibrated flow meter in parallel to the measurement streams. When proving is necessary the outlet of a given stream is diverted through the master meter, and the results are compared. Often the master meter stream will be used as the standby stream, reducing the cost of the system. It is important to know that the acceptance of this method is not global, and many ministries of oil do not allow this method.
Compact volume provers have gained a lot of acceptance over the past few years. These units use a piston with a shaft encoder to measure its displacement. These units occupy much less real estate than a ball prover, but they are costly. This method has limitations on the size of the flow meter that it can prove and is not typically accepted for proving ultrasonic flow meters.
The ball prover is the time-proven method and is universally accepted. There is the uni-directional prover and the bi-directional prover. Both of these methods use a polymer sphere that triggers displacement switches as it passes through a calibrated volume of pipe. This pipe section is calibrated using a water draw method in specific compliance with API and ISO methods. Craftsmanship is essential when constructing the calibrated section because any gaps or variation in ovality will cause this section to fail its calibration tests. An un-provable prover!
As its name suggests, the uni-directional prover moves the ball in only one direction. After the ball passes the calibrated section, it is transported upstream using a special piston. The unidirectional method is a longer but narrower design. With high flow rates, this method does not have the hydraulic shock induced by the 4-way valve used in the bidirectional prover.
The bi-directional prover works in two directions. A special four-way valve diverts incoming fluid to one of two ball chambers while diverting outgoing fluid to the other. Because the section is in a U-shape, this type of prover can be shorter.
When designing a bi-directional prover, you have to ensure that the four-way valve is seated in its full position prior to the ball triggering the first switch. The uni-directional prover does not require as much distance.
Ball provers are restricted to a minimum and maximum ball velocity. They also must have sufficient volume within the calibrated section to match the number of pulses generated by the flowmeter (minimum of 10,000) or be able to be derived through chronography using the flow computer.
Sampling & Analysis
Hydrocarbons such as Crude Oil and Natural Gas are priced in accordance with a variety of properties. Crude oil specially is always carrying various amounts of water. Nobody is paying for water. Technics’ principal design task is to provide a real-time representative sample for the fluid or gas to the analyzer and then monitor the analyzer itself to ensure that it is doing its work properly.
Our solutions in this field are complete systems. They include the extraction from multiple sources and the rapid transfer to the analyzer while treating the stream for pressure, flow, temperature, and contamination. Waste recovery systems collect, store, and transfer the residuals.
Representative sampling often requires preparation in the pipeline itself by using the jet mixing common in the industry. This involves a pump extracting fluid downstream and returning it upstream through a nozzle in conformance with the practices specified by API and ASTM.
RVP Vapor Pressure analysis using the Mini-Method measurement principle, where a piston, containing a pressure sensor, is used to expand the headspace above the liquid. Heating the sample to the measurement temperature at a specified vapor-to-liquid ratio gives you the vapor pressure of the liquid.
Sulfur Content analysis using X-ray Transmission (XRT) gauging has long been an accepted technique for the measurement of total sulfur (S) in heavy hydrocarbon process streams
Water Content for BS&W analysis provided by manufacturers such as Easiflo or KAM, offers continuous, real-time data for net oil and net water, plus the conductivity, dielectric, and both real and imaginary parts of permittivity of the fluid.
Elemental Analysis for zinc, phosphate, etc. delivers rapid, non-destructive, multi-element analyses – from parts-per-million (ppm) levels to high weight percent (wt%) concentrations – for elements from aluminum through uranium using a 50 kV X-ray tube and SDD detector
Viscosity/Density meters are available as pipe insertion devices, and they typically have the desired resolution for the given application.
FT-NIR/MIR Analysis can be difficult to implement, but they promise to provide results on a wide variety of characteristics in crude oils and refined fuels. Acidity, Octane, RVP, and many, many others. However, these devices require modeling of an existing process
30 Years of custom design producing a proven suite of solutions
Frequently Asked Questions
What is a custody transfer metering system?
A custody transfer metering system is used to accurately measure hydrocarbons as ownership is transferred between parties. It provides an accurate and reliable measurement system as a critical part of any custody transfer activity because measurement errors can negatively affect both buyer and seller.
Why is proving important in hydrocarbon measurement?
Proving is important because it verifies that the metering system is measuring correctly. Verification is critical in custody transfer, helping provide confidence for owners, operators, and downstream buyers.
What types of flowmeters can be used in a Technics measurement system?
We support several flow measurement approaches, including ultrasonic meters, Coriolis meters, turbine meters, and positive displacement meters. Technics is not tied to a single manufacturer or measurement method and selects components based on application needs.
What are the advantages of ultrasonic flow meters?
Ultrasonic flow meters are especially well suited for high-volume systems because they offer strong accuracy, low pressure drop, and can be proven using a ball prover. They do require pressure and temperature compensation for certain measurement bases and may be less economical on smaller systems.
When is a Coriolis meter a good choice?
Coriolis meters are useful because they provide direct mass measurement and direct density measurement, and most models also include internal temperature measurement. They adapt well to changing densities, though size limitations and pressure drop can affect suitability for larger systems.
Are turbine meters still used in custody transfer?
Yes. Turbine meters have been used in custody transfer for a long time and can offer good accuracy and small-volume proving capability. However, they contain internal moving parts that wear over time and can be affected by debris.
Where are positive displacement meters typically used?
Positive displacement meters are one of the oldest technologies and are typically used on smaller systems where they can be economical. However, they include internal parts that can be susceptible to damage and pressure drop.
What is a multi-stream metering system?
A multi-stream metering system uses two or more metering streams, often in a duty/standby arrangement. The multi-stream designs can help reduce the size and cost of proving mechanisms while supporting larger flowrates, though they also add system complexity.
Why use multiple metering streams instead of one large meter?
Very large flowrates require larger and more expensive meters. Diverting flow through multiple streams can reduce the cost of unused standby capacity and lower the size and method requirements of the proving system.
What is a master meter proving system?
A master meter proving system uses a calibrated reference flow meter in parallel with the measurement streams. When proving is needed, the selected stream is diverted through the master meter and the results are compared. However, this method is not universally accepted in all jurisdictions.
What is a compact volume prover?
A compact volume prover uses a piston and shaft encoder to measure displacement. Compact provers use less space than ball provers and have gained broader acceptance, but they can be costly and are not typically accepted for proving ultrasonic flow meters.
What is a ball prover?
The ball prover is the time-proven and universally accepted proving method. It uses a polymer sphere moving through a calibrated pipe section, with displacement switches used to verify measurement performance.
What is the difference between uni-directional and bi-directional ball provers?
A uni-directional prover moves the ball in one direction and returns it upstream with a piston, creating a longer, narrower design. A bi-directional prover works in both directions using a four-way valve and a U-shaped section, which can make the system shorter.
Why is calibrated prover construction so important?
The calibrated section must comply with API and ISO methods, and craftsmanship is essential because gaps or ovality variations can cause the prover to fail calibration. In other words, poor construction can result in an unprovable prover.
What is representative sampling in hydrocarbon systems?
Representative sampling means obtaining a real-time sample that accurately reflects the actual fluid or gas stream being measured. This is one of Technics’ principal design tasks, especially for crude oil and natural gas measurement and analysis systems.
What does a sampling and analysis system include?
Technics’ sampling and analysis solutions are complete systems that can include sample extraction from multiple sources, rapid transfer to the analyzer, stream treatment for pressure, flow, temperature, and contamination, and waste recovery systems for residuals.
How is water content measured in crude oil systems?
BS&W water content analysis provides continuous, real-time data for net oil and net water. This matters because crude oil commonly carries water, and water content directly affects product value.
How is sulfur measured in hydrocarbon streams?
X-ray Transmission (XRT) gauging is a long-accepted method for measuring total sulfur in heavy hydrocarbon process streams.
Are viscosity and density measurements available?
Yes. Viscosity/density meters are available as pipe insertion devices and can provide the resolution needed for the application.
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