Author: Chip Bremer
At the May 6-9 Offshore Technology Conference, Emerson’s David Andrew will discuss a new pressure sensor technology that could have a significant impact in a variety of offshore and downhole oil and gas applications.
The single crystal integrated capacitance sensor, a key technology in Emerson’s Paine 420-22-0010 Series Pressure Transmitter, is a highly reliable pressure sensor that has the potential to reduce costs and increase yield in offshore exploration and production. Its ability to stabilize rapidly to thermal effects while exhibiting excellent long-term drift behavior make it ideal for use in subsea and offshore environments.
To demonstrate its capabilities, this new sensor was subjected to a series of qualification tests in comparison to other industry-leading technologies.
Pressure transmitters for downhole and offshore use need to withstand higher temperatures, environmental stimulation, and higher reliability in comparison to their industrial counterparts. Different technologies are suited for distinctive subsets of pressure measurement due to limitations and capabilities inherent in different device designs.
Today, there are two types of pressure transmitters commonly used for offshore and downhole applications: piezoresistive devices and thickness-shear mode (TSM) quartz resonating devices. Piezoresistive devices comprise elements that alter resistance characteristics with changes in strain; however, their performance in offshore applications is limited because of their drift rate.
TSM quartz resonating technology is considered the industry standard because of its low drift rate and highly accurate results. These sensors operate by squeezing a resonator disk around the perimeter to modulate the frequency. They typically use two separately-housed quartz resonators: a pressure sensor, which responds to changes in pressure, and a reference crystal, which compensates for changes in temperature.
To demonstrate performance advantages, the single crystal integrated capacitance sensor underwent rigorous qualification testing of various characteristics–design, accuracy, stability, pressure drop response, thermal transience, and resolution – in comparison to quartz-based devices.
Not only did the transmitters pass fatigue, burst and accuracy requirements, but they also exhibited less pressure drop error and less thermal transient error than the quartz-based technologies.
The key to thermal transient reduction is the unique design, which houses the reference capacitor and the sensor capacitor in the same compartment. Because TSM quartz resonators have their reference crystals in separate compartments, they are often subject to thermal separation and greater thermal transient error and stabilization time.
In addition, the single crystal integrated capacitance sensors don’t suffer from twinning effects at higher pressures and temperatures that tend to cause inaccuracy in quartz resonators.
The single crystal integrated capacitance technology is currently used for production monitoring but can be customized for a multitude of offshore applications, including pressure calibration and measure while drilling (MWD) applications.
The single crystal integrated capacitance sensor technology has capabilities that the industry standard technologies do not, opening doors to innovative alternative applications that the sensor could be used in, from metrology applications to higher thermal gradient applications that require stability.
To learn more about how this new sensor technology, catch David’s presentation during the OTC technical session, Going the Distance: Subsea Electrical and Production Systems, which starts at 2:00 PM on Wednesday, May 8, in Room 606.
Visit us in the 2019 Offshore Technology Conference section on Emerson.com for more on ways to interact with the Emerson oil & gas industry team at OTC. You can also connect and interact with other oil & gas experts in the Oil & Gas group in the Emerson Exchange 365 community.