Study On Chemical Sealing Technology For Casing Leakage In Oil And Water Wells

With the increase of production time,China’s oilfields have basically entered the middle and late stages of development.In order to further improve oil recovery,major oilfields mainly improve oil recovery through secondary and tertiary recovery.When the reservoir is operated by water injection,gas injection,thermal oil recovery,chemical injection and microbial oil recovery,the environment faced by the casing is more complex and the casing damage is aggravated.On the other hand,geologic factors such as formation heterogeneity,formation fault activity,earthquake and crustal movement make the casing of oil and water wells subject to SRess shearing and formation fluid corrosion,which makes the casing damage more and more serious.Because of casing damage,wellbore leakage reduces oil field production,deSRoys normal injection-production well pattern,causes huge waste of oil and gas resources,disrupts normal production deployment,brings many blindness to macro-decision-making and specific management,and causes huge economic losses to oil field.Casing damage and leakage has become one of the key factors reSRicting oil field production.Based on the actual situation of Jianghan oilfield,this paper systematically and comprehensively analyses the mechanism of casing damage,leakage point and the damage situation of each block in Jianghan oilfield from different perspectives of casing damage.It is found that the salinity of formation water content is high in Jianghan oilfield,and formation fluid corrosion is the main cause of casing breakage.Casing breakage mainly occurs in unconsolidated wells above cement return height,accounting for 93.9%.In Jianghan Oil Region,casing leakage is the most serious in Jinghezhen formation,accounting for 52.8%.Casing failure is the main type of casing failure in Zhongshi,Xingou,Laoxin and Haokou blocks.Casing failure in Haokou,Eastern,Zhongshi and North fault blocks accounts for a high proportion of total wells in the block,and casing failure is more serious.Therefore,this paper presents a method of using hydrogel to isolate formation fluid through density difference to achieve floating plugging and settlement plugging,which can effectively plug casing damage and perforation in Jianghan area.In this paper,sedimentation and floating plugging system,water-proof gel system and a simulated plugging device are mainly studied.