Red Eye Water-Cut Meter

Quick Links to Information Below

• Red Eye Water-Cut Meter Overview
• Why is the Red Eye Water-Cut Meter so Accurate
• General Principle of the Red Eye Water-Cut Meter Operation
• Typical Applications of the Red Eye Water-Cut Meter
• Specifications of the Red Eye Water-Cut Meter

Red Eye Water-Cut Meter Highlights

Insensitive to entrained gas Ignores salinity and dissolved gas Unmatched accuracy at high water cuts Full-range water cut, 0 to 100% Inline for continuous real-time accuracy Field-proven ruggedness and reliability Convenient one-point field calibration Easy installation and service Full factory support Affordable for widespread automation

• Red Eye Water-Cut Meter Smart Transmitter
• Red Eye Water-Cut Meter Partial Customer List
• Advantages of the Red Eye Water-Cut Meter

Red Eye Water-Cut Meter Overview

There has always been a gap between the accuracy and the economics in getting accurate water and oil cuts from a well. Conventional well testing methods are labor intensive and require time and extrapolation from intermittent tests making them inherently inaccurate for real-time well monitoring.

The Red Eye® meter bridges the gap by providing an accurate water-cut meter priced for most wells. eP is able to do this by using state-of-the-art rifle-shot spectroscopy. This technology is being used around the world to accurately measure water-cut and with eP's Red Eye Multiphase Metering System (REMMS), it provides precise oil, water, and gas composition in real time.

The Red Eye is a revolutionary water-cut meter that uses a patented optical sensor technology. It employs technology based on the bulk transmission of infrared radiation through an oil-water mixture. eP worked closely with field and operations people from a major oil company to develop a product that meets the application requirements, but more importantly, one that meets the field functional requirements. The Red Eye is designed top-down to be user-friendly from routine operation to maintenance.

The Red Eye is used with over 1,000 wells worldwide.

Why is the Red Eye Water-Cut Meter so Accurate?

Because the Red Eye meter detects oil rather than water like some other water-cut meters, its accuracy actually improves as the water cut increases. At the highest water cuts accuracy reaches 0.25% of full scale or better. As water cut approaches zero, accuracy approaches 5% which meets or exceeds most well testing requirements. The Red Eye is a true full-range water-cut meter. Unlike other water-cut meters, response is unaffected by transition from continuous oil phase to continuous water phase.

Gas bubbles can cause a misinterpretation in some meters, making them see excessive oil. However, to the Red Eye meter's light, gas looks essentially like water, with a negligible effect on net oil measurement.

The content of field-produced water can and does vary from well to well even in the same formation. Since the Red Eye's measurements are independent of salinity, acidity (pH), solids content (TDS), and density, water content changes do not require recalibration. Additionally, since the Red Eye does not use gravity in its calibrations, its accuracy does not suffer when the oil is nearly as heavy as the water.

General Principle of the Red Eye Water-Cut Meter Operation

How does it work?

Red Eye meters measure the volumetric proportion of oil in a mixture of petroleum and water by passing a beam of infrared light through the stream. The instrument is designed for maximum sensitivity at high water cuts by using a narrow band of wavelengths for which water is effectively transparent and oil is a strong absorber. Accuracy is maintained under a wide range of conditions by taking into account not only the directly transmitted beam, but also light scattered forward and backward across the gap. A full function flow computer houses sensor receiver circuitry and transmits a water cut signal. It also calculates total oil and water flow for well tests, using a signal from any flow meter.

Absorption Spectroscopy

The Red Eye sensor exhibits the following desirable properties. At the operating frequency of the sensor, water is the transmitting phase while oil is the attenuating medium. Water transmits close to 100% of the emitted radiation while crude oil typically transmits less than 10% of the light.

The Red Eye Water-Cut Meter is not affected by variation or changes in the properties of the water since the NIR radiation does not interact with the components of field produced brine.

The Red Eye Water-Cut Meter uses the basic principle of spectroscopy, relying on the large difference in the absorption of near infrared radiation between crude oil and water. Differentiation is achieved by operating over a very narrow band of radiation with maximum intensity occurring at a wavelength where crude oil and water exhibit large differences in opacities.

The Red Eye sensor interaction with oil, water, and free gas (also called entrained gas) is summarized below:

• Crude oil is the absorbing medium of the near infrared radiation.
• Variation in crude oil density over the producing life of a well does not affect the oil calibration factor.
• Water is a non-absorbing medium.
• Variation in water properties does not affect the transmission of the NIR radiation.
• Free gas (entrained gas, limited measurements have shown that up to 10% gas void fraction has little or no effect on the Red Eye sensor) transmits NIR radiation like water.
• Solution gas does not affect the Red Eye performance.

These properties make the Red Eye sensor essentially an oil-cut meter that is particularly suited for high water-cut applications. This includes well testing of high water-cut wells and wastewater (from field produced brine) treatment and monitoring.

Mechanical Features

The optical components are shielded from the flow by glass windows fused on the metal body of the probe. The probe approach makes the optical components of the sensor accessible without removing the spool piece from the flow line. This allows for service without down time.

Two "light pipes" are inserted into a flow cavity with a resulting effective area slightly greater than that of the inlet and outlet pipes. This feature ensures very little pressure drop at the maximum flow designed for a given pipe size.

Red Eye Water-Cut Meter Smart Transmitter

The Red Eye Model ST00-XS Smart Transmitter was designed to meet the requirements of field installations and the rugged demands of the petroleum industry for application power, versatility, reliability, and ease of use.

The transmitter works with the entire family of Red Eye Water-Cut Meters and provides a digital or analog output of the water cut for input into a SCADA system or local RTU.

The Red Eye Smart Transmitter features a battery-backed memory that allows the user to configure and store the calibration parameters for up to 40 wells (or process applications).

The transmitter comes with LinkPlus™ Windows® based software for configuration.

Typical Applications of the Red Eye Water-Cut Meter

Individual Well Monitoring

The Red Eye meter can be used to monitor individual wells and provide continuous real-time, water-cut data that can be used to optimize the yield from the entire reservoir maximizing the owner's return on investment. Individual well monitoring also provides data for real-time analysis of the well production. This data can be used alone or incorporated into a host based analysis system for well optimization.

Continuous Individual Well Testing

The Red Eye meter, in conjunction with a mass flow meter, has performed very well in wellhead monitoring applications even in situations where free gas is present. This new technique uses standard measuring devices on streams up to 15% GVF.

Net Oil Measurement in Periodic Tests

The Red Eye is used for automated measurement of net oil in periodic tests of individual wells. To calculate and totalize the flow of oil and water, the flow computer receives a signal from a liquid flow meter and multiplies that quantity by the measured water cut from the Red Eye sensor.

Net oil metering of liquid from two-phase separators is much more economical than the alternative automation method, which is a three-phase separator with individual metering of gas, oil, and water streams.

Group Production at Centralized Facilities

Implementing the Red Eye at a group production facility provides the same benefits as the periodic test unit. It is much more economical than a three-phase separator.
The fluid from each satellite flowing to a central oil-water separator is measured by the flow meter while the Red Eye measures the water cut. The flow computer then calculates the total amount of water and oil by multiplying the water cut by the total fluid volume.

Dewatering Monitoring Systems for Crude Oil Tanks

When a Red Eye is installed on the discharge line from a tank, the operator can easily identity the rag layer (interface between the oil and water in the tank). The optical sensors of the Red Eye sense very small amounts of the rag layer as it passes through the pipe allowing the operator to shut off the flow from the tank. Conductivity-type probes do not match the accuracy of the Red Eye because there is such a small difference between the rag layer and the water that floats it. Using the Red Eye allows water to be transferred with virtually no oil from the tank.

Specifications of the Red Eye Water-Cut Meter

Red Eye Water-Cut Meter Partial Customer List

Advantages of the Red Eye Water-Cut Meter

Unmatched Accuracy at High Water Cuts

Because the Red Eye meter detects oil rather than water, its accuracy improves as the water cut increases. At the highest water cuts, accuracy reaches 0.25% of full scale or better. As water cut approaches zero, accuracy approaches 5%-better than most meters achieve throughout their range.

Insensitive to Entrained Gas

Gas bubbles trick some other meters, making them see excessive oil. But in the Red Eye meter's light, gas looks essentially like water, with no effect on oil fraction measurement.

Ignores Salinity and Dissolved Gas

Since its measurements are independent of water and oil densities, the Red Eye meter does not have to be recalibrated for different water salinities or different amounts of gas dissolved in the oil. Similarly, its accuracy does not suffer when the oil is nearly as heavy as the water.

Full-Range Water Cut, 0 to 100%

The Red Eye is a true full-range water-cut meter. Unlike other water-cut meters, response is unaffected by transition from oil continuous to water continuous flow regimes.

Field-Proven Ruggedness and Reliability

No moving or vibrating parts. Solid semiconductor electronics endure harsh conditions and rough treatment.

In-Line for Continuous Real-Time Accuracy

No slipstream or sampling error. No signal delay. Less uncertainty in rapidly fluctuating concentrations.

Full Factory Support

Users can count on excellent documentation, instructions, troubleshooting help, and spare parts availability.

Affordable for Widespread Automation

Due to the simplicity of its operating principle and construction, the Red Eye meter makes oilfield automation economically feasible on a much wider scale than before.

Convenient One-Point Field Calibration

Factory calibration for 100% water never needs adjustment. Field calibration is simple and quick.

Easy Installation and Service

The sensor assembly installs as easily as a valve. The electronics are removable without depressurizing the line.