Test method for water lock damage evaluation of tight sandstone

Abstract

The invention provides an evaluation test method for water blocking damage of tight sandstone. The method comprises the following steps: preparing a core sample, and passivating and drying the core sample at a high temperature; performing saturation treatment on the core sample to obtain a core sample subjected to saturation treatment; performing centrifugation on the core sample subjected to saturation treatment by a high-pressure centrifugation device to obtain a core sample subjected to centrifugation; performing first magnetic resonance imaging test on the core sample subjected to centrifugation to obtain first water saturation Swi of the core sample; testing gas log permeability Kwgi of the core sample with the first water saturation Swi and testing gas log permeability Kwcgi of initial water saturation Swci of a stratum; obtaining change rate Dn of the core sample with the first water saturation Swi relative to the initial permeability of the stratum according to the gas log permeability Kwgi of the core sample with the first water saturation Swi and the gas log permeability Kwcgi of the initial water saturation Swci of the stratum. The water blocking damage degree can be evaluated comprehensively with the method.

Description

technical field [0001] The invention relates to oil exploitation technology, in particular to a test method for evaluating tight sandstone water lock damage. Background technique [0002] During the development of unconventional tight sandstone oil and gas reservoirs, due to the infiltration of foreign water phase fluid into the oil and gas layer pores, the original oil in the oil and gas layer will be pushed to the deep part of the oil and gas layer, and a concave oil (gas) layer will be formed at the oil (gas) / water interface. ) phase meniscus. Capillary resistance is formed at the meniscus due to surface tension. If the energy of the reservoir is not enough to overcome the capillary resistance, the clogging of the water phase cannot be eliminated, resulting in an increase in the water saturation of the reservoir and affecting the storage and recovery factor. And this kind of damage is called "water lock damage". [0003] The water lock damage evaluation methods current...

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Problems solved by technology

[0005] The present invention provides a test method for evaluation of tight sandstone water lock damage to eliminate the interference of factors such as water-sensitive expansion, salt precipitation, and uneven distribution of saturated water in the prior art, and the problem of evaluating water lock damage without considering the initial water content conditions of the formation

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