Offshore Wellhead Production Line Monitoring using WAND Sensors
Inductosense, in partnership with Oceaneering, conducted an 8 month trial of the WAND system on a wellhead production line on a platform in the Caspian Sea, located off the eastern coast of Baku, Azerbaijan. The purpose of the trial was to demonstrate the repeatability, reliability, durability and accessibility of the WAND sensors and system within an offshore environment
Production streams from wellheads often contain significant sand content and internal erosion of the flowline is a concern. Internal erosion has an impact on production and safety and it is therefore important to understand the rate of erosion at various locations on the flowline. The traditional method of determining the erosion rate requires skilled NDT inspectors to be on the rig to acquire thickness measurements from locations using ultrasonic NDT. However due to human error accurate trending of this data is not possible* and there are also costs associated with facilitating the inspection (eg travel to the rig, bed-space).
THE INDUCTOSENSE SOLUTION
The Inductosense ultrasonic WAND sensorsprovide accurate monitoring of wall-thickness and enable trending of corrosion rates. The sensors are permanently installed, battery-free and wireless. The sensors are activated when the WAND Data Collector is brought close to the sensor.
For this application WAND sensors were permanently installed onto various locations on a selected flowline. Using the WAND Data Collector repeatable, reliable, measurements can be acquired quickly with just the press of a button on the probe when close by to the sensor. There is no need for accurate alignment or coupling gels and a maintenance engineer on the rig could take the measurements. The data can then be sent for analysis, reporting and sign-off remotely.
OFFSHORE TRIAL RESULTS
Prior to the trial, the Oceaneering team was trained to correctly install the sensors and operate the WAND system. Oceaneering then successfully installed 10 sensors onto elbows of the selected flowline in April 2017. Before installation, as a base reference, a manual ultrasonic thickness reading was taken at the position where the piezo element would be installed.
Using the WAND Data Collector, regular measurements were then taken over several months. These measurements were calibrated to the thickness value obtained from the manual testing performed during the installation of the sensors. Repeatable measurements were achieved over the 8 month period with less than 0.05mm variance.
The trial confirmed that:
The WAND sensors can be easily installed in an offshore environment, making it possible to acquire fast and repeatable measurements.
The permanent WAND sensors and contactless acquisition system provided consistent and accurate results for the eight months that they were installed and used for gathering thickness readings.
The variances between readings far exceeded the expected tolerance levels of conventional manual ultrasonic thickness readings, and, in most cases, these variances were less than 1/100mm.
*See for example: Wilson, P.T., Krouse D.P., Statistical Analysis of UT Wall thickness data from corroded plant, Nondestructive Testing Australia, Vol 41,No.3, 2004.