油气层保护用淀粉微球承压能力评价研究

Evaluation of Pressure Bearing Capacity of Starch Microspheres for Oil and Gas Reservoir Protection

通过对自制淀粉微球粒径分布、承压能力和岩心端面微观形貌分析可得,微球的D10、D50、D97分别为3.00、18.68和92.05μm,粒径的区间百分含量呈偏差正态分布。淀粉微球在中高渗岩心中承压能力最高,最大可达16.3 MPa,说明岩心在(50～70)×10^(-3)μm^2渗透率下的孔喉尺寸与淀粉微球的粒径更加匹配。而在低渗岩心中,淀粉微球承压能力不佳。从岩心端面电镜图发现中高渗岩心在入口端和出口端均可见微球状物质,说明有部分微球颗粒已嵌入岩心孔喉,并且少量微球颗粒在岩心内部发生运移。由此可见,此粒径分布的淀粉微球在渗透率大于50×10^(-3)μm^2的中高渗地层将会发挥较大"屏蔽暂堵"作用。

By analyzing the particle size distribution,compressive pressure bearing capacity and core end micro-morphology of self-made starch microspheres,it was found that the D10,D50 and D97 of the microspheres were 3.00,18.68 and 92.05μm,respectively.The percentage content of the interval of particle size was deviated from normal distribution.Starch microspheres had the highest compressive pressure bearing capacity in medium and high permeability cores,up to 16.3 MPa,which indicated that the pore throat size of core at(50~70)×10-3μm2 permeability was more matched with the size of starch microspheres.In low permeability cores,the compressive pressure bearing capacity of starch microspheres was poor.Microspheres were found at the entrance and exit of the medium and high permeability cores,which indicated that some microspheres had been embedded in the pore throat of the cores,and a small amount of microspheres had migrated inside the cores.It can be seen that the starch microspheres with this size distribution will play a large role of temporary shielding plugging in medium and high permeability formations with permeability greater than 50×10-3μm2.