The On-Line Monitoring Technology For The Casing Outside Pressure And The Casing Strain Based On The Fiber-Optic Sensing Technology

Oilfield casing not only bring economic losses, but also oil field development program and the application of enhanced oil recovery measures adversely affect, directly affecting the development of oil fields, well casing damage has become the hard problem of China's oil fields. In recent years, domestic and foreign scholars have been conducting research damaged well casing, casing damage mechanism in a certain degree of understanding achieved, but there is no effective way to prevent and mitigate the damage cased hole, therefore, to grasp the casing deformation and stress and strain, early prevention and treatment has become an urgent problem.In accordance with the special circumstances of oil well and characteristics of Daqing oil field casing, made using fiber-optic sensors monitoring strain and pressure oil well casing, to achieve the set of pipe inspection, early warning, pre-loss control purposes. Main research work and achievements are as follows.First, making the analysis of fiber grating sensor and fiber-optic Brillouin sensors external pressure during oil well casing pipe and casing deformation when the strain monitoring of the working process.Secondly,according to the Daqing oil field casing shear damage characteristics,designing a pressure of FRP reinforcement sensitivity program, designing a sensor to monitor the small layer of pressure,completing the pressure calibration tests, verifing that the pressure sensor's practicality.Finally, Through the establishment of the ANSYS Mechanical model of casing shear to get the access to the theoretical value of early warning, using casing shear test system to simulate the progress of casing shear to obtain early warning limits. Established a method which with the casing of the axial strain to assessment of the security situation in the casing.Completing the sets of optical fiber sensor networks monitoring damage test structures and the analysis of data collected in the underground,determining the security state of the casing through comparing to the warning limit damage of laboratory test.Through the real-time monitoring experiment, it shows that the casing real-time monitoring system based on the fiber-optic sensors can reflect the axial and circumferential casing stress real-timely and accurately. It is significant to forecast the casing damage accurately and reduce economic losses.