Study On Monitoring Scheme For Composite Flexible Pipe Based On Optical Fiber Sensing Technology

Oil and gas pipelines are the lifeblood of national industry and economy,which affect all aspects of social life,and mainly include metal pipe,metal flexible pipe and composite flexible pipe.Compared with the former two kinds of pipes,the composite flexible pipe has some advantages of light weight,low pressure loss and strong corrosion resistance.It has a broad market prospect and will be the main development direction of oil and gas pipeline in the future.Oil and gas pipelines are often faced with complex external environment,which are prone to corrosion,deformation,leakage and fatigue damage.Once the pipeline accident occurs,it will cause huge economic losses and environmental pollution.On the one hand,the traditional pipeline monitoring methods have some problems of limited monitoring range,high cost,low efficiency,which haven’t meet the growing monitoring needs.On the other hand,the new optical fiber sensing technology has many advantages,such as anti electromagnetic interference,high monitoring sensitivity,waterproof,corrosion resistance,small size and low cost.It can realize the function of long-distance continuous on-line monitoring.Optical fiber sensing technology is the main direction of oil and gas pipeline health monitoring research in the future.For the new type of glass fiber reinforced thermoplastics(GFRT)composite flexible pipe,the monitoring scheme of GFRT pipe based on optical fiber sensing technology is studied in this paper:(1)This paper has summarized the current situation of oil and gas pipeline health monitoring technology,analyzed the advantages and disadvantages of various monitoring methods,and highlighted that optical fiber sensing technology is the focus of pipeline health monitoring research in the future.(2)This paper has introduced the structure and classification of optical fiber,the mechanical properties of optical fiber,the principle and characteristics of fiber grating sensing technology and distributed fiber sensing technology.(3)Based on the material composition and structural type of GFRT pipe,the market prospect of GFRT pipe in the field of oil and gas exploration and development is described in detail.Based on the homogenization theory,the calculation method of effective elastic constant of GFRT pipe is proposed and verified by finite element method,which provides help for the design and production of GFRT pipe.(4)The monitoring scheme of GFRT pipe based on optical fiber sensing technology is proposed.The optical fiber implantation method is studied and its feasibility is verified.(5)The indoor model test of GFRT pipe deformation,impact and vibration monitoring based on optical fiber sensing technology is carried out.The accuracy and feasibility of optical fiber monitoring technology are verified by analyzing the strain data of fiber bragg grating sensor and resistance strain gauge.The results show that the pipeline equivalent method based on homogenization theory can accurately calculate the effective elastic constant of GFRT pipe.The monitoring scheme of embedding optical fiber winding into GFRT pipe can effectively ensure that the optical fiber sensor is not damaged and improve the monitoring efficiency.Fiber bragg grating sensor can effectively monitor the deformation,impact and vibration along the pipeline,and can accurately locate the impact location,with good monitoring effect.