Experiment on micro imbibition mechanisms of tight reservoirs based on a microfluidic model
Aiming at the problems of long core imbibition duration,inaccurate measurement and the existing microscopic model not involving the typical throat size of tight reservoirs,in this study,a novel microfluidic model made of corroded sili-con-glass to simulate the pore structures in tight reservoirs was designed,in which different throat size,pore shape,pore throat ratio,throat and pore connection position can be considered.The consistency of internal wettability of the pores and channels was achieved through high-temperature silicon oxide coating.A series of imbibition experiments using distilled wa-ter-oil and oil-isopropanol-distilled water were carried out.The results show that there is a film flow inside the throat,and its velocity is much faster than that of the moving suction meniscus.The irregular suction interface can be caused by the rough-ness of the inner surface of the throat,and the film flow has a significant impact on the pore throat infiltration effect.At the early stage of imbibition,the contribution of wide throats to imbibition is far greater than that of narrow throats,and the in-crease of wettability is conducive to the imbibition of the wetting phase towards the expanding area.The film flow can avoid blocking of the wetting phase in the throats,but it continues to flow towards the outlet in the form of discontinuous film flow.Smaller wetting angle and tortuosity are conducive to imbibition.The longer of the imbibition distance,the more uniform of the leading edge of imbibition,and the coordination number,pore shape and size have less influence on imbibition.The im-bibition is mainly determined by the size of the opening at the contact position between pores and throats,and the wettability determines the overall effect of imbibition in various pore throat structures.
tight reservoirimbibition mechanismmicrofluidic modelwetting phase system
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