A method and device for analyzing the starting pressure gradient law of weakly cemented argillaceous siltstone

By constructing an analysis system and method for the initiation pressure gradient law of weakly cemented argillaceous siltstone, the problem of accuracy in the analysis of aqueous displacement test results was solved, and the accurate determination of the aqueous initiation pressure gradient of low-permeability loose argillaceous siltstone was achieved, thus improving the accuracy and precision of the analysis.

CN120402066BActive Publication Date: 2026-01-27INSTITUTE OF GEOLOGY AND GEOPHYSICS CHINESE ACADEMY OF SCIENCES
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Patent Information

Application Number
CN202510481990.3
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2025-04-17
Publication Date
2026-01-27
Estimated Expiration
2045-04-17

AI Technical Summary

Technical Problem

Existing technologies lack accurate analytical methods to process the test results of aqueous phase displacement experiments, especially in the process of natural gas hydrate seepage in low-permeability loose silty mudstone. The study of the initiation pressure gradient mainly relies on oil phase displacement experiments, which cannot accurately reflect the actual situation of aqueous phase displacement.

Method used

A system and method for analyzing the initiation pressure gradient law of weakly cemented argillaceous siltstone is provided, including a timing unit, a pressure sensor, a liquid level sensor, and a processing system. By constructing a core confining pressure variation map, the actual liquid outlet point and the minimum initiation pressure gradient are determined. Combined with a data cleaning module, the relationship between pressure gradient and liquid production rate is analyzed, and the relationship between minimum and pseudo-initiation pressure gradients and formation parameters is fitted.

Benefits of technology

It improves the accuracy of data analysis, determines the law of water phase initiation pressure gradient in low-permeability loose argillaceous siltstone, and can more accurately reflect the changes in core seepage characteristics and formation fluid properties, especially under water phase displacement conditions, thus improving the accuracy of analysis.

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Abstract

The application discloses a weakly cemented argillaceous siltstone starting pressure gradient law analysis method and device, which comprises the following steps: constructing multiple test cores; performing displacement tests on each core holder, timing each displacement test, and recording the displacement pressure, confining pressure change and displacement fluid capacity of the core holder; determining the starting pressure gradient in combination with the confining pressure change of the core holder in each displacement test, determining the real liquid production point of the test core in the displacement test process, and obtaining the minimum starting pressure gradient of each test core; fitting the relationship between the pressure gradient and the liquid production rate to obtain the pseudo starting pressure gradient of each test core; and fitting the relationship between the minimum starting pressure gradient and the pseudo starting pressure gradient and the formation parameters; the application determines the real liquid production point of effective displacement, improves the accuracy of data analysis, and determines the change law of the water phase starting pressure gradient of low-permeability loose argillaceous siltstone with the core seepage characteristics and the properties of formation fluid.
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