Preparation And Performance Evaluation Of Self-healing Agent For Cement Stone Cracks In Oil And Gas Wells

In the application of cementing and self repairing,oil and gas self repairing is usually used as the main way to repair micro fractures.Cement-based osmotic crystalline waterproof agent(CCCW),as a unique rigid waterproof material,has a broad prospect for engineering application because of its durable waterproof effect and good self healing properties.The traditional cement-based permeable crystalline waterproofing agent is mainly used as paint or powder to add to concrete,so as to achieve the purpose of impervious and waterproof.Based on the research of building based waterproof materials,the self repairing agent CW,which is suitable for oil well cement,is modified and synthesized.It is of great practical significance to improve the self-healing research of the cementing engineering in China through the research on the development and mechanism of the self repairing compound of the cementing project and the self healing mixture of water type of oil well cement with independent intellectual property.This paper mainly focuses on the following contents:first,consult the literature to understand the research status of the self healing of cementing cement ring in China and foreign countries,and analyze the permeable crystalline waterproof masterbatch of existing buildings.The components of the permeable crystalline self repairing materials are divided into three categories:carboxylic acid,silicon containing auxiliaries and silicon free auxiliaries.Two kinds of indoor cement stone micro cracks are made by"one word formation".The rate of change of permeability of cement and stone before and after the repair of cement stone is the main evaluation index,and the self repairing activity of malic acid is determined by orthogonal experiment.Secondly,malic acid,polyethylene glycol and concentrated sulfuric acid were used as the main raw materials,and the modified product CT was obtained through esterification reaction.By single factor experiment,the synthesis conditions of CT were optimized as:malic acid:polyethylene glycol:concentrated sulfuric acid was 1:2:0.8%,reaction temperature was 90 ℃,reaction time was 3h,and the molecular structure of CT after separation and purification was analyzed and characterized.In the end,CT can be combined with other active additives to get the water type self repairing agent CW of oil well cement,CW and other admixtures added to the slurry,which can meet the basic performance requirements of the cementing slurry,and have no obvious influence on the comprehensive performance of cement slurry,and no effect on the late compressive strength of the water debris.The results of CW self repairing test showed that the recovery rate of compressive strength reached 92.8%and the permeability recovery rate reached 94%at 80 degree temperature.Compared with the blank sample and the self repair of hydrocarbon,SEM and XRD show that CW can produce branches and tendrils at the crack.The self repairing cement slurry with self repairing agent has a better self repairing ability than the blank,and has two better self repairing effects.Finally,the mechanism of osmotic crystallization of self repairing agent CW is discussed based on pore structure analysis.CW mainly promotes the formation of hydrated calcium silicate on the surface of matrix cracks,thus realizing the self repairing effect of micro cracks in cement paste.