Method and device for quantitatively characterizing wettability of rocks in shale reservoir

Abstract

The invention provides a method and device for quantitatively characterizing wettability of rocks in a shale reservoir. The method comprises the following steps: obtaining shale in the shale reservoir, and preparing a shale sample; performing a spontaneous infiltration experiment on the shale sample to obtain a self-priming slope; calculating a wettability index WI by using WI=(P1-T1)-(P2-T2); performing quantitative characterization evaluation on the wettability performance of the shale sample: the wettability index is within the range of -0.5 to 0; if the wettablity index is closer to -0.5,the water dampness behavior is stronger, otherwise, the shale sample is closer to blended water dampness; when the wettability index is 0, the shale reservoir is in blended dampness; the wettability index is within the range of 0 to 0.5; if the wettability index is closer to 0.5, the oil dampness behavior is stronger, otherwise, the shale sample is closer to blended oil dampness. According to themethod, by introduction of a new wettability index, the wettability of the shale reservoir can be accurately and quantitatively characterized; the method has important significance for designing an effective yield increase technology and estimating the ultimate recovery factor.

Description

technical field [0001] The invention belongs to the field of exploration and development of shale reservoirs, and relates to a method and device for quantitatively characterizing the wettability of shale reservoir rocks, in particular to a method for quantitatively characterizing shale reservoir rocks based on spontaneous imbibition experiments and wettability indices Methods and apparatus for wettability. Background technique [0002] Wettability refers to the propensity of a solid to come into contact with one fluid rather than another, and reflects the balance between surface forces and interfacial tension. When a drop of preferential wetting fluid falls on the surface covered with wetting fluid, the preferential wetting fluid will displace another fluid to spread or even cover the entire surface; while a drop of non-wetting fluid drops onto the surface covered with On the surface of the wetting fluid, the non-wetting fluid will try to minimize its contact area with the ...

AI Technical Summary

Problems solved by technology

Secondly, the contact angle method fails to consider the heterogeneity of the shale surface, and the mineral composition of conventional oil and gas reservoirs is relatively simple, while shale contains many different components, especially organic matter, and the wettability of different components is different. resulting in uneven wettability

The second problem with using contact angle to characterize the wettability of shale reservoirs is that it only reflects the local wettability of shale and cannot take into account the heterogeneity of shale surface

[0006] At present, there are relatively few measurement methods suitable for shale reservoir wettability, and each method has its own limitations, which affects the judgment of shale reservoir wettability to a certain extent, and thus affects the Oil and Gas Reservoir Development Effect

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