Method for determining fault activity in structural stable period

Abstract

The invention relates to a method capable of accurately determining multi-stage active periods of a fault in a structural stable period. The method comprises the following steps of acquiring vertical principal stresses in different periods based on a vertical principal stress-depth relationship of a current stratum and stratum burial depths in different periods; determining the minimum principal stress in different periods based on the pressure-stress coupling relation of the current stratum and the stratum pressure and the vertical principal stress in different periods; based on the maximum principal stress, the minimum principal stress and the formation pressure in the different periods, the maximum effective principal stress and the minimum effective principal stress in the different periods being obtained; determining stress Moire circles in different periods based on the maximum effective principal stress and the minimum effective principal stress; based on the internal friction angle-burial depth relation of the current stratum and the stratum burial depths in different periods, critical fracture envelope lines in different periods being obtained; comparing the stress Moire circles at different periods with respective corresponding critical fracture envelope lines; and judging the opening and closing properties in different periods according to the position relationship between the stress Moire circle and the critical fracture envelope line.

Description

technical field [0001] The invention belongs to the technical field of oil and gas exploration, and in particular relates to a method for determining fault activity in a stable structure period. Background technique [0002] Fault activity is crucial to processes such as subsurface fluid flow, accumulation and mineralization, and earthquake-induced mechanisms. It is a hot and difficult point in the application research of earth science and engineering. In particular, faults play an important role in oil and gas migration, accumulation and preservation. They can not only serve as pathways for oil and gas migration, but also effectively block oil and gas to form oil and gas reservoirs. The fault evolution process includes an active period and a static period. During the active period, faults are often open, which is conducive to the migration of oil and gas along the high-permeability fault zone or damages the accumulated oil and gas reservoirs. The role of faults in hydrocar...

AI Technical Summary

Problems solved by technology

However, it is difficult to obtain downhole core samples drilled in fault zones, which limits the popularization and application of this method in the study of oil and gas accumulation.

[0004] To sum up, the existing fault activity analysis methods are not suitable for the analysis of fault activity phases in the structurally stable period, which restricts the research on the relationship between faults and hydrocarbon accumulation.

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