A new acoustic data-logging system from 2H offers real-time riser monitoring on demand
Deepwater riser monitoring has come a long way in recent years. Part of the reason for this is the efforts made by 2H Offshore to convince the industry of the importance and value of monitoring and also to develop accurate and reliable sensors and logging systems, the key to converting the concept into a reality.
In relatively simple monitoring systems, data from motion and strain sensors are recorded using stand-alone loggers attached to the riser at various locations along its length. These locations are selected on the basis of the anticipated response of the riser system. Data are literally brought to the surface periodically using ROVs to recover the loggers.
Online systems use the same types of sensor; however, with these, data are constantly transferred to the surface via electrical umbilical cables. While this offers clear advantages to the user – notably, immediate access to the data – system installation is less straightforward and the subsea cables add to the overall cost and complexity of the systems.
According to Karim Jan, 2H’s sales and marketing manager, the company’s latest product – an acoustic data logger, the INTEGRIpod™-MA – offers the simplicity of a stand-alone system with the increased versatility of an online version. He says, “The new device builds on the standard INTEGRIpod data logger, of which more than 300 have seen service in over 50 monitoring applications around the world, at depths to 2800 m. The unit has the same pressure-rated and corrosion-resistant container as the standard logger. Something else it has in common with the standard logger is that it works with the full range of 2H INTEGRI sensors. This means that parameters other than motion, such as temperature and pressure, can also be monitored online using the system.”
Data are easily retrieved from the new loggers using a dunking acoustic modem, which can be either pole- or winch-mounted on the surface facility. Significantly, the loggers can also be reprogrammed via the modem. “Should environmental conditions change or response anomalies occur, the operator can alter the frequency of logging or concentrate on selected measurements,” says Jan. “For example, if a severe storm is forecast, the system can be put into almost constant monitoring mode. Once the threat has passed, the recorded data can be quickly accessed to determine the condition of the riser and to help make decisions on resuming production. The device enables sensing to be carried out on demand; we believe that, ultimately, the new technology has the power to increase uptime and deliver significant added production value.”
Another advantage of acoustic logging systems is that they can be retrofitted using ROVs. In practical terms, they are no different from stand-alone systems and can be installed with minimal disruption to normal operations. “This latest development illustrates how far riser monitoring has progressed,” says Jan. “We can now provide a range of off-the-shelf monitoring equipment that can be readily configured to meet operators’ individual needs. From being a research technique a short time ago, riser monitoring has evolved into a highly practical and interactive integrity management tool.”