Petroleum Software esmerGL Gas-Liquid Flow Meter

The esmerGL is a low cost cone-based meter that reports liquid and gas flow rates in oil, condensate and wet gas lines across the whole GVF range, without a separator or complex sensors. Petroleum Software Ltd offers it as a mobile or a fixed metering system, and it can add water composition through its esmerCAP capacitance technology.

Field unit and flow computer

The primary element is a cone with the usual pressure, temperature and differential pressure set, delivered by a Yokogawa MVT EJX 910A multivariable transmitter. The cone is interchangeable, giving a beta ratio between 0.5 and 0.75. A Beckhoff flow computer in an Exd enclosure on the field unit runs the I/O and processing in real time, outputs to SCADA over Modbus, and drives a four line local display of liquid and gas rates and the primary readings of pressure, temperature and differential pressure. No flow conditioning is needed and the meter can be installed horizontally or vertically.

Technical specifications

Flow models and tune-up

esmerGL Runtime Software executes industry standard fluid dynamic and thermodynamic models: a Bernoulli based flow model, an equation-of-state model built from PVT laboratory or test separator data, and a correlation predicting the cone discharge coefficient as fluid and process conditions change. The esmerGL Configurator, run offline on a Windows PC connected by Bluetooth, Wifi or Ethernet, creates these models and uploads them to the flow computer. PSL says the configuration procedure complies with API 2566 guidelines.

Where it fits

Typical duties are wellhead or manifold lines carrying oil, condensate or wet gas where a test separator is unavailable or too slow. Accuracy depends on GVF, water composition, PVT data and tune-up, so an accuracy target is stated for each application. Related instruments are in the flowmeters category.

Installation and operation

The esmerGL needs no flow conditioning and can be installed horizontally or vertically, which helps on crowded skids and short pipework. The field unit carries the transmitter, the manifold and the Exd flow computer together, so site work is mainly the process connections, a 220 VAC supply drawing about 20 W, and an RS485 Modbus link to SCADA. A desktop PC, notebook or tablet is needed only to run the Configurator, and it can connect to the flow computer over Bluetooth, Wifi or Ethernet, so engineers can tune the meter from a convenient location. The four line display on the field unit shows liquid rate, gas rate and the raw P, T and DP readings, which lets an operator confirm the meter is healthy without a laptop.

Tuning data come from two sources. Equation-of-state models are built from PVT information supplied by the user, taken from laboratory fluid analysis or from a test separator. The cone discharge coefficient correlation is built from historical data collected by the instrument itself, which means the correlation improves as trend data accumulate. Until the next tune-up the same correlations are used to predict liquid and gas flow at actual and standard conditions in real time.

Information to send with an enquiry

Provide the line size within the 2 to 10 inch range, pressure class, design pressure and temperature, the expected gas and liquid rates, the water cut and GVF range, the area classification, and the PVT report. PSL sizes each application specially and issues an accuracy target for it, so a complete data set shortens the quotation cycle.

The multivariable transmitter and the cone share one compact field unit, so a single meter can cover both the liquid and the gas leg duty of a production line, and the interchangeable cone lets the same body be re-fitted with a different beta ratio if flow rates change over the life of the well. The brochure lists materials to NACE and ASME standards, which is the usual basis for sour service pipework, and a certified Exd flow computer keeps the electronics inside the hazardous area boundary.

Commissioning and verification

General engineering note (not from the brochure): a gas-liquid meter of this kind depends on correct fluid data and a correctly selected cone beta ratio. At start-up, confirm that the fluid properties used by the flow computer match the latest PVT analysis, check the Yokogawa EJX 910A configuration against the meter data sheet, and compare the liquid and gas rates with a test separator or tank measurement over a stable production period.

The interchangeable cone is useful when production changes. If the gas rate falls well below the original design, a cone with a different beta ratio can restore a usable differential pressure without replacing the spool. Keeping a record of each cone change, together with the flow computer configuration, helps the metering engineer explain any step change in the reported rates during audits.

Documents and quotation

The manufacturer brochure is attached to this page. The picture shows the esmerGL cone family as illustrated by PSL. Seven Star LLC is an independent supplier based in Muscat and prepares quotations on request, without published prices.