Effect mechanism of working fluid on productivity of low permeability gas reservoir and reservoir protection
The difference of clay minerals in low permeability gas reservoirs in the East China Sea leads to different formation damage mechanisms,unclear understanding of the impact on productivity after contact with foreign fluids,and lack of mechanism support for reservoir protection research.In view of the above problems,the mechanism of reservoir damage was studied with the actual drilling and completion liquid sys-tem of H gas field in the East China Sea.The dynamic damage evaluation experiment was optimized by u-sing gas as displacement medium,extending cycle time and establishing initial water saturation.Further-more,a mathematical model of mud filtration depth and skin factor is established to analyze the mechanism and significance of the productivity damage caused by drilling and completion fluid system.Finally,reser-voir protection technology for H gas field is selected.The experimental results show that the initial fluid inva-sion speed is fast,and it remains unchanged after 5 days.The productivity impairment is mainly caused by snap-off,water compatibility,and pore-throat blockage.Choosing the right solid particles and increasing fluid pressure can effectively reduce the damage due to drilling and completion fluid.The research results provide a fundamental guide to increase the productivity of low-permeability gas reservoir.
low-permeability gas reservoirworking fluidsreservoir damagereservoir protectionmech-anism study
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