Aquaterra Energy has launched a riser monitoring system (RMS) that uses a combination of direct riser strain measurement, subsea data logging and riser analysis processing algorithms to generate real-time operational guidance for drilling and workover operations in water depths up to 100 m (328 ft). The system uses a bespoke standard-length riser joint that would replace a standard riser joint in the stack-up, with pre-installed data acquisition and logging hardware.
“Heightened sensitivity around health and safety and project critical risks associated with riser fatigue have resulted in an urgent need for innovation in riser integrity management, driving our innovation in this field,” Eric Doyle, Regional Director – Europe at Aquaterra Energy, said. “This new RMS will assist our clients with precision planning of maintenance activities and deliver real potential for safe asset life extension.
He continued: “The integration, complexity and practicality of the data handling in the RMS is unique to Aquaterra Energy, and the accumulated strain data can either be stored locally or transmitted back to surface for live evaluation.”
Aquaterra developed a full-scale prototype of the RMS unit in the structures laboratory of the University Engineering Department at the University of Cambridge. In partnership with the university, all elements of the system have been tested and verified.
Dr Chris Burgoyne, Head of Structures at the University of Cambridge, said: “This is an interesting use of sensing technology for the offshore oil and gas industry, and the structures group is happy to be working with Aquaterra Energy on such an innovative application.”
The RMS uses pre-processed computationally intensive data to ensure that analysis, including the usually time-intensive component fatigue utilization determination, is rapid and that a full range of potential input conditions, tabulated in a multi-dimensional matrix, is provided. Measurement, evaluation and specification of key variables, specific to each strain cycle contained within the measured data, allow an accurate representation of the critical boundary conditions to be produced. This subsequently enables comparison with the pre-processed data, as well as directional fatigue assessment for each constituent component along the full riser length.
The system’s four strain gauge devices facilitate superior reliability and accuracy to alternative data acquisition methods. The gauges are protected from accidental damage by a casing, which also contains the logging hardware. Modular battery pack expansion slots facilitate up to five years of logging time.
“Unlike conventional methods, abutment to the riser is by a specially developed subsea epoxy resin, achieving one of the product’s key objectives – measuring the riser and not a clamp,” Mr Doyle said. “This improves riser stain measurement accuracy whilst eliminating the need for welding, which causes damaging fatigue hot spots.”
The RMS is fully compliant with DNV-RP-F206 and ISO 13628-7 specifications and certified to ATEX Ex ib IIB T4.