绒囊暂堵液堵漏机理研究

Study on mechanism of transient fluid plugging in chorionic sac

绒囊流体因其具有较好堵漏性能,广泛应用于钻完井、修井等石油工程勘探开发各个阶段。明确绒囊流体堵漏的微观机理可以更好的指导现场堵漏。室内测定了绒囊内绒囊的粒径分布、封堵岩心的孔喉分布及封堵压力,利用微观实验装置观测其基质孔隙内的充填暂堵过程,最后结合理论分析明确绒囊流体微观堵漏机理。结果表明,体系内绒囊的粒径分布0~350 μm,岩心孔喉的粒径分布0.7~15 μm,同一绒囊流体封堵4种岩心封堵压5.42~17.65 MPa且随着渗透率的减小而增大,绒囊通过聚集、变形可对基质孔喉、微裂缝进行全面封堵。根据拉普拉斯定理结合室内实验结果可知,绒囊流体堵漏的微观机理为:岩心内的绒囊流体在流动过程中压缩变形产生了附加阻力,大量的附加阻力相互叠加产生了封堵压力,阻止了井漏的发生。

The fuzzy-ball fluid is widely used in various stages of petroleum engineering exploration and development such as drilling and completion,workover and so on because of its good plugging performance.Clarifying the microscopic mechanism of fuzzy-ball fluid plugging can better guide on-site plugging.The particle size distribution of the fuzzy-ball,the pore throat distribution of the plugging core and the plugging pressure were measured in the laboratory.The filling and temporary plugging process in the matrix pores was observed by the microscopic experimental device.Finally,the microscopic plugging mechanism of the fuzzy-ball fluid was clarified by theoretical analysis.The results show that the particle size distribution of the fuzzy-ball in the system is 0~350μm,and the particle size distribution of the core pore throat is 0.7~15μm.The plugging pressure of the same fuzzyball fluid plugging four kinds of cores is 5.42~17.65 MPa and increases with the decrease of permeability.The fuzzyball can comprehensively plug the matrix pore throat and microcracks through aggregation and deformation.According to the Laplace theorem and the indoor experimental results,the microscopic mechanism of the fuzzy-ball fluid is that the compression deformation of the fuzzy-ball fluid in the core produces additional resistance during the flow process,and a large amount of additional resistance superimposes each other to produce plugging pressure,which prevents the occurrence of lost circulation.