Tracking method of proppant movement trajectory in fractures under high particle concentration experimental conditions

Abstract

The invention discloses a method for tracking the movement trajectory of proppant in fractures under the experimental condition of high particle concentration, which comprises the following steps: S1: making a dyed proppant and treating it as a tracer particle; S2: combining a certain proportion of the dyed proppant with After the conventional proppant is evenly mixed, the sand-carrying liquid is prepared, and the physical simulation experiment of proppant transportation is carried out; S3: Use a high-speed camera to obtain the movement state of the tracer particles during the experiment, and use image processing software to capture pictures at fixed time intervals from the video; S4: Perform secondary coloring on the proppant tracer particles, and use a computer program to identify the tracer particles in the intercepted pictures; S5: Use a computer program to calculate the velocity and track the tracer particles after identification. The method provided by the invention can accurately identify and track the migration trajectory of proppant particles under high-concentration conditions, facilitates the study of all proppant migration mechanisms in the hydraulic fracturing process, and is of great significance for guiding hydraulic fracturing construction.

Description

technical field [0001] The invention relates to the technical field of proppant delivery experiments in hydraulic fracturing physical simulation experiments, in particular to a method for tracking proppant movement tracks in fractures under high particle concentration experimental conditions. Background technique [0002] Hydraulic fracturing is a necessary means for the development of unconventional oil and gas (tight gas, shale gas). Its principle is to use high-pressure pumps to pump fracturing fluid into the formation, and when the fracture pressure of the formation is exceeded, the oil and gas reservoir will be opened to release the oil and gas. Oil and gas production capacity, to achieve the effect of increasing production, and improve oil and gas recovery. After the reservoir is opened, proppant particles will be injected into the formation to keep the opened fractures at a certain degree of opening when the pump is shut down on the ground, so that the formation maint...

AI Technical Summary

Problems solved by technology

[0003] Most of the existing methods for studying the migration of proppant particles use large-scale physical model experiments to qualitatively study macroscopic phenomena such as proppant laying patterns, but do not test and analyze the migration state of proppant during the experiment. Migration mechanism to fully analyze proppant migration

The particle tracking technology has been applied in various multiphase flow fluid experiments, among which the PIV and PTV methods are more widely used, but its scope of application is the flow field test under the condition of low concentration particles less than 8%, while In the actual production process, the proppant concentration is mostly 20%-40%, which is much higher than the measurement range of the two technologies. It is difficult to identify and track proppant particles directly by particle image velocimetry

Under the condition of high concentration (concentration greater than or equal to 15%), the interaction between proppant particles is enhanced, which will cause particle occlusion during tracking, and the tracking process of proppant particles will have a serious impact, thus causing particles to appear during the identification process Lost, a large amount of flow field information is lost, and it is difficult to track proppant particles under high concentration conditions

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