Apparatus and Method for Monitoring the Mechanical Properties of Subsea Longitudinal Vertical Components in Offshore Drilling and Production Applications

Abstract

An apparatus to monitor the loads and mechanical behavior of subsea longitudinal vertical components of off shore drilling and production platforms (SLVCs) uses sensors attached directly to the tendons by adhesive or by friction mount. The sensors are typically in a sensor ring assembly which is placed around the perimeter of the SLVC. Ruggedized cables carry the sensor reading from the ring assembly to the SLVC working platform and to a control center for monitoring the action and stresses on the tension legs. The system may be deployed on existing SLVCs or may be installed on new construction during initial assembly and installation.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The subject invention is generally related to measuring systems for monitoring the effect of environmental elements on subsea components in offshore oil and gas drilling and production and is specifically directed to fiber optic sensing systems employed as monitoring and measurement apparatus.[0003]2. Discussion of the Prior Art[0004]Offshore drilling and production systems include a surface working platform in communication with a production field beneath the seafloor. All such systems have one feature in common, which is that a conduit of some sort is required to support drilling equipment and materials being delivered from the surface work platform to the subsea field, and / or a conduit for lifting oil and gas being produced from the subsea field to the surface work platform. In typical cases the conduit is a tubular pipe extending from the subsea field to the surface, generally referred to as a riser.[0005]One such e...

AI Technical Summary

Benefits of technology

The invention provides a new way to monitor the stress, strains, twisting, tension, compression, temperature, and motion of subsea pipes and other components using fiber optic sensors instead of traditional strain gauges. This system is more reliable and durable, and it can be installed at any time during the construction or operation of the offshore system. The components are low cost and easy to install. The system also includes a temperature compensation sensor to correct for temperature effects on the strain measurement. The apparatus and method of monitoring the structural loads on subsea pipes are particularly useful for determining the viability of offshore platforms. The system can also be retrofitted to existing systems for cost savings. The components are protected from damage and moisture intrusion by a polymer or composite housing and a ruggedized cable.

Problems solved by technology

Historically, the load cells are unreliable and often fail early in their service life.

When the monitoring system fails it is often necessary to shutdown the platform at great expense and loss of production time.

All of these are of limited functional value and are subject to early fatigue caused by the rigorous conditions in which they are employed.

Most monitoring and measuring systems employed on SLVCs have to be installed during initial construction, and cause major shutdown periods and expense when they fail.

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