裂缝监测用磁性支撑剂制备与性能

Preparation and performance of magnetic proppant for fracture monitoring

以二价/三价铁盐、聚二甲基二烯丙基氯化铵以及陶粒等为主要原料,应用逐层组装法制备了一种裂缝监测用磁性支撑剂,结合单因素实验优选了磁性支撑剂制备工艺条件,通过扫描电镜(SEM)、振动样品磁强计(VSM)等手段表征了磁性支撑剂的结构与性能,应用自制裂缝监测模拟装置考察了磁性支撑剂充填裂缝后磁异常信号的分布特征。结果表明,优选的磁性支撑剂制备工艺参数为:0.5%的纳米Fe_(3)O_(4)颗粒、0.3%的聚二甲基二烯丙基氯化铵、反应体系pH值为10、反应温度为60℃、以及交替组装3次;制备的支撑剂表面包覆大量磁性颗粒,磁滞回线呈S形单线,无外加磁场时,剩磁和矫顽力都接近于零,具有超顺磁性,饱和磁化强度为6 emu/g,磁响应距离为31.4 mm;磁场作用下,磁性支撑剂产生明显的磁异常信号,越靠近支撑剂磁异常值越大,并随埋藏深度增加磁异常值减小,而磁异常等值线反映了充填在裂缝中的磁性支撑剂不同分布形态,从而为裂缝监测用磁性支撑剂矿场应用及数据分析提供依据。

A magnetic proppant for fracture monitoring was prepared by layer-by-layer assembly method using divalent/trivalent iron salts,PDADMAC,and ceramsite as main raw materials.Combined with single factor experiments,the process conditions of magnetic proppant preparation were optimized.The structure and properties of magnetic proppant were characterized by means of SEM and VSM,and the distribution of magnetic anomaly signals after the magnetic proppant filled the cracks was investigated by self-made fracture monitoring simulation device.The results show that the optimal preparation parameters of magnetic proppant are:0.5%nano-Fe_(3)O_(4)particles,0.3%PDADMAC,pH value of reaction system is 10,reaction temperature is 60℃,and the number of alternate assembly times is 3.The prepared proppant is coated with magnetic particles,and the hysteresis loop is a S-shaped single line.When there is no external magnetic field,the remanence and coercivity are close to zero,and it has super paramagnetism.The saturation magnetization is 6emu/g,and the magnetic response distance is 31.4 mm.Under the application of the magnetic field,the magnetic proppant generates a significant magnetic anomaly signal,the closer the magnetic proppant is,the larger the magnetic anomaly value is,and the magnetic anomaly value decreases with the burial depth increasing.The isoline of magnetic anomalies reflects different distribution forms of the magnetic proppant filled in the fracture,thus providing a basis for the application and data analysis of the magnetic proppant for fracture monitoring.