Ultrasonic sensors in subsea oil & gas production current use and opportunities By Bjørn Stevning Hole Senior Product Engineer, TechnipFMC 5/31/2018 Page footer text 1
What is ultrasound and how can ultrasound be used to measure? Example applications mostly limited to marine and subsea environment Measurement objective in subsea application The subsea sensor context limitation and requirements Some core technologies we use and Sensor for current subsea production system Future use of ultrasound in next generation sensors
What is ultrasound and how it can be used for sensor applications subsea? High frequency sound - loosely defined as what cannot be detected by humans typically sound with frequency higher than 20kHz Transfer of sound in a material is a mechanical movement and transfer of energy. The media can be solid, gas or fluid The mode of the sound depends on the material property and its shape Some effects create ultrasound that can be detected and processed. These are typically production of sand and debris, gas breakthrough, pig detection, leakage of process fluid to sea and fatigue We can transmit an ultrasound signal into a structure By inspecting the received signal, we can learn about the thickness of a pipe, location of reflections from pittings in a flow line, velocity of a media, distance to an object, even temperature of a piece of material and generally the state of the material Page footer text 3
Examples of use General marine environment Ultrasound technology is an established technology with literary thousands of applications, products and techniques used in many areas Rich area of knowhow, available topside sensors and expertise Related use that can be of interest for subsea production environment Sonar Communication subsea Imaging of seabed Seismic Wave profiler and current profiler Find fish and submarines - passive and active ROV use and submarine ranging and navigation Page footer text 4
Examples of use Subsea production environment Measure sound from production Sand production Gas breakthrough Pig detection Fatigue Communication and navigation during ROV operations Active system Wall thickness measurement Erosion and Corrosion monitor Flow measurement of hydraulic line, chemical lines Measure position for hydraulic accumulator piston and levels in subsea storage tanks Integrated into subsea pumps and monitor health of shafts and bearings Page footer text 5
What can be measured and why do we want to measure? When wavelength and the wave mode is matched to the material, we can measure: Density Thickness Speed/Flow speed General material properties Flow properties Detect changes in the production flow sound signature Reasons to measure: Identify erosive particles Quantify the effect of erosion Quantify the erosion agent Measure corrosion and the effect of inhibitors Control loop - flow loop, measuring flow speed and amount of chemical Measure leak of hydrocarbon to sea Monitor risk and fatigue Page footer text 6
Subsea sensors and typical requirements High reliability and accurate measurement throughout the field s lifetime Maintain integrity for intrusive measurement Stringent control and qualification of design and manufacturing process Only use technology ready to be marinized A failure is expensive Non-intrusive sensors have less stringent requirements like those from the API regime, but we still have high demand on function, design and production processes. Design and production of electronics and verification of quality Design of function and verification on accuracy Design of sea water barriers and coupling between the transducer and structure Example specification for an Intrusive probe 15000 psi and 177 degrees Celsius intrusive probe 30 years design life High flow speed - gas at 30m/s High level of vibration Insulation of electronics High accuracy, low drift and aging MTBF >100 years A large range of flow conditions Fully compliant with API (design, testing, qualification, inspection and verification) Page footer text 7
Traditional Conservative thinking for subsea sensor challenges or limits the use of available ultrasound technologies! Page footer text 8
Ultrasound technology in subsea sensors Piezoelectricity The most used ultrasound technology subsea is based on the piezo electric effect A common transducer design is made of PZT PZT is Lead Zirconate Titanate and can be made in a multiple shapes and sizes The PZT element design must match the frequency band for the transducer Broadband achieved with a backing material The front layer should be macthed to the media PZT gives out a small voltage when receiving acoustic energy the ceramic is deformed and sets up an electric field The PZT element will change shape when exposed to an external voltage and can be used as a transmitter A piezo electric element can also act as an actuator Complex manufacturing process that allows different shapes and sizes Page footer text 9
Ultrasound technology in subsea sensors Electro Magnetic Acoustic Transducer and LAMB wave An alternative to PZT is EMAT EMAT uses a permanent magnetic field and a high current pulse to create an ultrasonic wave in a structure Less dependent on a couplant or matching layer Can be used to generate and detect LAMB wave Less accurate compared to PZT less energy sent into the object Sligthly easier to adapt to the environment no permeable interfaces «Contactless» The induced signal is a RF signal and penetrates down to the skin depth of the pipe. It is a fairlry good match for surface wave like the LAMB wave A LAMB wave is a plate wave that changes velocity depending on the thickness of the plate Page footer text 10
Next generation sensor using ultrasound A few topics that can be of interest for research, development and future application Sensor with High MTBF, high quality and low cost Explore both new topside technology and marinize this and old technology Real time condition monitoring of the sensor (temperature monitoring, black box etc.) Explore new materials and 3d printing More retrofit of sensors Ultrasound lean itself to non-intrusive sensing and has a coupling to material and physical effects that are of interest Use system approach and flow assurance to define instrumentation scope AI and robotics Page footer text 11
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