Study Of Crustal Stress Tesing And Regional Well Casing Damage Monitoring Based On Fibre Sensing

With the continuous development of the oil exploitation, in particular, theimplementation of high-pressure water exploitation is being used in order toimprove the production in the lately oil fields, which directly causes casing damage.There are many reasons casing damage, in which crustal stress is the root cause. Inaddition, crustal stress is also the important affection to other underground projects.Located in the casing perforations section is the main layer of casing damagesegments. As the accuracy of used monitoring methods was not high, the casingdamage was detected only when it severely damaged. Therefore this is always led tothe whole oil well scrapped, which caused gigantic economic losses.This paper has respectively established numerical model of confining pressurein non-oil layer、numerical model of crustal stress in oil layer and vertical stressanalysis methods based the theory of elasticity mechanics, with the application ofthe optical fiber sensing technology. Has built up a stress monitoring system basedthe optical fiber sensing technology. Has finished experiment to an oil well in Jilinoil filed.This paper has achieved quasi-distributed testing of the minimum andmaximum stress in key layer, achieved distributed testing of the vertical stress, andcompared the results with other methods, results indicated that the test results areaccurate and reliable.This paper has done modeled analysis of different parameters which affectingthe strength of casing perforation using ANSYS software. They were pore sizes,pore density and phase angles. Results showed that different parameters’ affectionwere different. In addition, further, did a more in-depth analysis of the non-uniformstress and formation water creep on the formation strength of casing perforations.This paper has built up the area oil wells casing damage monitoring systembased the optical fiber sensing technology and oil well drilling technology, finishedexperiment to four oil wells in Jilin oil filed. Achieved an online real-timemonitoring, and calculated on-site monitoring data, did analysis of circumferentialstrain in key layers and axial strain changes in the vertical direction.Experimental results show that the stress numerical model、ground-basedoptical fiber sensing technology stress and regional oil wells casing damagemonitoring system can do real-time and accurate measurement of stress and casingdamage state, which is to provide a new method of stress detection technology andis very meaningful to decrease casing damage in oil field.