Shiquan Jiang

Study and Test of a New Bundle-Structure Riser Stress Monitoring Sensor Based on FBG.

To meet the requirements of riser safety monitoring in offshore oil fields, a new Fiber Bragg Grating (FBG)-based bundle-structure riser stress monitoring sensor has been developed. In cooperation with many departments, a 49-day marine test in water depths of 1365 m and 1252 m was completed on the “HYSY-981” ocean oil drilling platform. No welding and pasting were used when the sensor was installed on risers. Therefore, the installation is convenient, reliable and harmless to risers. The continuous, reasonable, time-consistent data obtained indicates that the sensor worked normally under water. In all detailed working conditions, the test results show that the sensor can do well in reflecting stresses and bending moments both in and in magnitude. The measured maximum stress is 132.7 MPa, which is below the allowable stress. In drilling and testing conditions, the average riser stress was 86.6 MPa, which is within the range of the China National Offshore Oil Corporation (CNOOC) mechanical simulation results.

Strain monitoring of drilling riser in deepwater based on fiber Bragg gratings

It is very important to monitor the lateral and axial strains of drilling riser for evaluation its health in deepwater. An optical fiber strain sensing system based on optical fiber Bragg gratings (FBGs) used for monitoring the strain of drilling riser is presented. The optical fiber strain sensors are made by embedding FBGs into thin columned fiber reinforced polymer which protect FBGs from seawater corrosion. Four optical fiber strain sensors are installed parallel to the riser axis and arranged at 90° angles around the riser by a home-made metal belt, at the same time, twelve resistance strain gauges are pasted near the sensors around the drilling riser at 30° angles as reference sensors. A scaled drilling riser about 1 meter long and 0.245m diameter is pressed in the lateral and axial direction in the range of 0-400KN, the experimental results show that the relative error between optical fiber strain sensors and resistance strain gauges is less than 6%.

Research on Strain Measurement of Abyssal Riser with FBG Sensors

Marine riser fatigue damage in the hostile ocean environments is the fatal issue for deep and ultra deep waters petroleum and gas drilling and productions during. Strain detecting provides a direct measure of the riser fatigue. One riser fatigue monitoring formula based on FBG sensor with orthogonal distribution was researched which takes into account temperature compensation function. Mathematical model for calculating stress and bending moment of riser with the relative change in the Bragg wavelength was presented. One riser stress-strain measuring device based on FBG sensor was designed. Strain measurement tests of a riser scale model were performed. The study shows that the riser fatigue monitoring formula based on FBG sensor presented in this paper is reasonable, and the research results provide the technical support for field practice.