Study On Permeability Affects Casing Stress In The Decompression Process Of Injection Well

Decompression process of the injection well caused the phenomenons of casing damage are increasingly serious,drilling and well operations often use decompression operation in rectified area,in order to complete the injection-production workload and shorten the time of decompression adopts blowout blowdown,however in the process of injection wells blowout blowdown owing to casing inside and outside differential pressure shall cause the casing damage,and that defective gradation not only in connection with decompression working system but also in connection with formation permeability.So,we have to research on the permeability to the influence to the casing stress during decompression process of the water-injecting well.First,this paper aims at the mechanism of the water-injection well pressure relief,worked out that water-injecting well pressure relief to cause the casing damage result by the coupling of stratigraphic seepage field and stress field,so in this paper,based on the mechanism of the pressure relief of the injection wells,combined with software of finite element analysis to numerically simulated the problem which about the casing damage of the water-injecting well pressure relief,established the mechanical model of casing damage of the pressure relief,in consideration of the influence of the permeability,reached that in different permeabilities,in difference of well depth to set up the casing mechanical model of the uniform and nonuniform crustal stress;confirmed in the different permeabilities,to worked out the critical decompression value which let the damage does not occur.Second,this paper with a view to different well spacing and array pitch,came to finite element analysis about the five-spot pattern,seven-spot pattern,anti-nine-spot pattern,reach a conclusion of instantaneous pressure relief to the influence of the stress of the casing.According to the influence of the calculated pressure relief of the injection wells caused casing damage,came to the conclusion that the condition of the casing damage,In the end choosing Daqing Putaohua reservoir in calculating examples,to analysis the effect of injection pressure on casing damage.This article research results not only can be used in the evaluation of the casing damage caused by the decompression of the injection wells,but also make guidance to oil fields in the department to make a reasonable scheme of pressure relief.