Subsea metrology requires accurate, precise and robust measurements which are critical for successful fabrication and installation of spools and jumpers. It can take six to eight hours or longer to complete one measurement, but a recent project showed that by using our dedicated metrology software tool it’s possible to significantly reduce this.
The project was led by global offshore construction company, EMAS CHIYODA Subsea (ECS), who was contracted by Apache Energy to deploy its heavy lift deep water, multi-lay Lewek Constellation at the Julimar natural field off the coast of Western Australia. ECS’s scope of work included the installation of two manifolds, connected by five 30 metre vertical spools and five 80 metre horizontal spools.
Surveyors estimated that to complete the 10 metrologies, would take anywhere between 60 and 80 hours. So in a drive to save time and money, ECS turned to our dedicated metrology software ‘Connect’ to streamline the process.
Developed in partnership with survey engineering company, 4D Nav, Connect reduces operator workload by introducing ‘expert’ settings, automated data collection and robust processing of measurements from planning to report delivery.
The work at Julimar was conducted using five Compatt 6s and three Gyro- Compatt 6 transponders. The Compatt 6 units were deployed in a braced LBL array to support positioning the manifolds during installation and subsequent metrologies.
The GyroCompatts were installed in survey receptacles on the various structures for the same purposes. The Lewek Constellation’s own ROVs were used to move the Gyro- Compatts around; a task executed quickly and efficiently thanks to a manipulatorfriendly handle on each unit’s side and precision mechanical ‘stab’ on its base which, when placed in a ‘survey receptacle’ on each structure, precisely aligned the GyroCompatt relative to the structure’s north.
All of the metrologies were implied, no spool hubs were occupied. Data collection took advantage of Connect’s capability to load and integrate the data for multiple metrologies, analyse and QC it, then apply it to process individual metrologies. The survey team collected depth loop and profile data using an ROV held digiquartz depth sensor, then heading and inclination data at each survey receptacle whilst alsocollecting baseline measurements. The collected data was analysed as one data set. The site’s shallow water depth meant paying particular attention to sound velocity.
Connect’s ability to edit the sound velocity applied to individual and groups of baseline observations and reprocess multiple metrologies to evaluate the effect of the changes with a few mouse clicks, proved invaluable. Once the data QC was completed, each spool metrology was processed and the final report and plot generated. The report contains a summary of the results including hub-to-hub horizontal distances, slant range, depth differences, attitudes, plus details of the calculations to support the results.
Huge time savings
Speaking about the success of the Connect software utilised during the Julimar Project, Gerry Quinn, Survey Manager (Operations) with EMAS CHIYODA Subsea said, “Our team were blown away with the speed in which these metrologies were undertaken – in particular the unprecedented time of 26 hours total to measure five 30 metre vertical jumpers (Manifold to Wells) and five 80 metre horizontal jumpers (Manifold to Manifold to PLEMs) in 80 metres water depth. The 4-man Survey team conducted not just the metrology, but the overall operations as smoothly and as efficiently as one.”
If you would like to find out more about how Connect can help you save time, get in touch.
Sonardyne Inc. Houston