Why You Should Consider Diagnostic Surface Management for Oil & Gas Wells

Related Vendors

TURCK GmbH

Elementar Analysensysteme GmbH

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Ametek Crystal Engineering

AMETEK GmbH

Using Chart Recorders in Oil and Gas Well Monitoring

Pressure gauges, especially analog gauges, are typically fragile. Field versions exist but, outside the lab, accuracy may degrade with ambient temperature. They are useful as process gauges because they refresh constantly, require no batteries, and provide an intuitive indication of whether a process is within acceptable parameters.

Beyond this application, analog gauges become more problematic. Their metal diaphragms make them susceptible to damage from over-pressure. Their accuracy is usually low, and resolution is limited by how the dial is printed. Moreover, they can only display readings in one unit system, and taking readings requires time and training.

How Chart Recorders Work

Chart recorders use ink pens mounted on pivoting arms to produce graphs on moving paper charts. Their primary advantage is their ability to record for extended periods in remote locations. Chart recorders are available in weather-proof enclosures, but their excessive size and weight make them cumbersome. They must be handled with care while recording, to avoid disturbing their mechanical arms. The paper chart which records data must be replaced, protected from the elements, and returned to a lab for analysis. To use the recorded data when a chart is full, the graph must either be interpreted manually by a technician or scanned and processed by a computer.

Additionally, the accuracy of a chart recorder depends on changes in ambient conditions, as well as on the thickness of the pens - which may cause an error up to 1 per cent of the recorded reading.

A reference recorder is typically enclosed in a lightweight, hardened, polyurethane housing that is capable of withstanding impacts, temperature changes, and submersion in water. These devices read the output from modules which may detect pressure, temperature, current, or voltage and store data in digital memory. The modules are usually interchangeable, and recorders generally accept two inputs at a time. Modern reference recorders can be extremely accurate because they use a proprietary mathematical algorithm to correct for ambient temperature. Their interchangeable modules permit high accuracy measurements across a wide pressure range, in any unit system, and a menu system allows for customization and specialized features.

Reference Recorders – The Better Alternative for Oilfield Monitoring?

Reference recorders—like the nVision Reference Recorder by Crystal Engineering, shown connected to a gas well in Figure 6 and Figure 7, are poised to replace these and other oilfield instruments for some applications. This is part of a growing tendency toward using one multi-purpose device for several tasks.

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