A method for measuring spontaneous imbibition based on capacitive coupling

Abstract

The invention discloses a spontaneous infiltration measurement method based on capacitive coupling. The method comprises the following steps of arranging a plurality of pairs of excitation electrodesand detection electrodes on the surface of a to-be-detected rock core at interval, and putting the rock core in an insulation cylinder; applying peripheral pressure on the insulation cylinder; injecting displacing fluid into the rock core, obtaining conductivity distribution of the rock core by using a signal generating and processing system and further obtaining change of rock core saturation distribution along with time, so as to measure rock core spontaneous infiltration, wherein the signal generating and processing system comprises an AC excitation source, an inductive module, a signal processing system and a processing imaging and control system that are electrically connected in sequence, the excitation electrode and the inductive module are electrically connected, and the detectionelectrode and the signal processing system are electrically connected. The method can monitor in real time change of saturation along with time in rock core spontaneous infiltration, is suitable for various possible spontaneous infiltration displacing modes from piston displacing and non-piston displacing, and can produce highly accurate saturation cloud maps of rock core surface and interior in real time.

Description

technical field [0001] The invention relates to a spontaneous imbibition measurement method based on capacitive coupling, which belongs to the fields of oil and gas field development engineering and porous medium seepage mechanism research. Background technique [0002] In the development of unconventional oil and gas resources, fracturing operations are often used to open the formation, increase the diversion effect of the formation, and then increase production. During the fracturing process, a large amount of water needs to be injected into the formation. The spontaneous imbibition effect is obvious due to capillary force, salt concentration and pressure difference in unconventional reservoirs. The spontaneous imbibition characteristic of rock is one of the important parameters of reservoir. Provide a theoretical basis for oil and gas reservoir screening, reservoir evaluation, technology application and improvement of oil and gas productivity. [0003] The current meth...

AI Technical Summary

Problems solved by technology

The above method has the following disadvantages: First, the method generally records page changes through a camera, and the human error factor is obvious

Secondly, if the spontaneous water absorption of the rock is not large, the error defect of this plan will be obvious, because the diameter of the glass tube is limited by the manufacturing process, if it is too thick, the change of the liquid level will not be obvious, if it is too thin, the glass tube itself will produce capillary effect, If the rise of the water surface is too high, and the upper part of the glass tube must be connected to the atmosphere, the water in the tube will inevitably evaporate, which will affect the experimental results.

Thirdly, the rock will expel the gas inside the rock in the form of bubbles during the process of water absorption. From the perspective of the structure of the experimental instrument, it cannot guarantee that the gas bubbles will be discharged from the thin glass tube, which affects the accuracy of the experiment.

Finally, the device can only study the mass of water absorbed throughout the core over time

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