Downhole Quartz Gauge Overview

posted on 15 January 2019 by James Wright

Choosing a quartz downhole gauge can be advantageous in certain situations. Quartz tools are more stable and have less drift than a Piezo tool. Typically you can go 2 years or more between calibrations with a quartz tool. Quartz tools are preferred for long-term high-temperature jobs.

Quartz sensors are made from quartz crystals. Specifically, in DataCan gauges, there is a quartz disc placed between two quartz drums. The disc vibrates like a drum skin in response to changes in pressure and temperature which results in a change in the quartz disc’s natural frequency.

If you need a high-temperature solution, you need quartz. Piezo sensors tend to drift at temperatures above 150 °C (the diffusion layer in the silicon die begins to leak resistance). Quartz tools will operate to temperatures around 200 °C, and the data will remain stable.

The transducer in DataCan's Quartz tools averages 10,000 measurements every second resulting in higher resolution data that gives a clearer picture of what is happening in your specific well. It is 100 times more resolution than a piezo tool (0.00006% vs 0.0003% Full Scale).

Downhole pressure and temperature measurement
Pressure up to 30,000 psi maximum
Accuracy of up to +/- 0.020% full scale
Resolution of 0.00006% full scale
Temperature up to 200 °C maximum
Accuracy of +/-0.25 °C
Resolution 0.005 °C
2 million data sets of memory
1 second to once a day sampling

All of DataCan’s quartz tools use hybrid oscillating circuits. Hybrid circuits are 100 times more reliable than standard surface mount (soldered) electronics.

Hybrids, like the one above, have no plastic parts. The raw die is mounted onto a ceramic substrate. The resulting structure is much smaller, and will work reliably to higher temperatures (up to 225°C).

Using modular memory cartages means that DataCan’s quartz tools can be upgraded in the field. At any time, a DataCan customer can change the memory module out for a surface readout module.

DataCan Quartz tools have significant advantages over the competition. DataCan’s quartz design maximizes the thermal response of the quartz sensor. The picture below shows the caged bullnose that DataCan uses to expose the pressure (green) and temperature (red) crystals to the wellbore.

DataCan’s mechanical package uses electron beam welding to reduce leak paths. DataCan has one tool joint, the competitions’ tools have up to three. As well as reducing the number of potential leak paths, DataCan has improved its seal joint. A common seal failure is an extrusion. DataCan’s seal design uses metal-to-metal bevelled seal to eliminate the extrusion gap.

Check out our quartz downhole memory pressure gauges, quartz downhole permanent pressure gauges, and quartz surface pressure transmitters.