Study on mechanism of transient fluid plugging in chorionic sac
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 0～350 μm,and the particle size distribution of the core pore throat is 0.7～15 μm.The plugging pressure of the same fuzzy-ball fluid plugging four kinds of cores is 5.42～17.65 MPa and increases with the decrease of permeability.The fuzzy-ball 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.
Drilling and completionPluggingFuzzy-ball fluidLeakage sealingMicroscopic mechanism
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