Method for identifying maximum paleo-stress direction in strike-slip fracture development period

Abstract

The invention provides a method for identifying a maximum paleo-stress direction in a strike-slip fracture development period. The method comprises the following steps: finely explaining strike-slip fractures, dividing strike-slip fracture superposed upheaval sections, superposed pull subsections and translation sections, selecting typical splicing sections, identifying a local principal stress direction, and establishing a stress field numerical simulation geology and mechanics model of the typical splicing sections; loading regional stress fields in different directions to the model in the direction range of the regional stress field of strike-slip fracture; and determining the direction of the maximum paleo-stress in the strike-slip fracture development period. The invention has the advantages that the method comprises establishing a relationship between a secondary fracture trend in a strike-slip fracture splicing section and a corresponding regional stress field direction; and identifying the maximum paleo-stress direction in the strike-slip fracture development period, so the method has important guiding significance in knowing the regional structure background, analyzing thecause and evolution of strike-slip fracture, discussing the development law of a derived fracture-fracture system at different parts of strike-slip fracture and controlling storage and reservoir.

Description

technical field [0001] The invention relates to the field of geological structure analysis, in particular to a method for identifying the direction of the maximum paleo-stress during the development period of strike-slip faults. Background technique [0002] Restoration of the paleo-tectonic stress field is crucial to understanding the nature of tectonic movements in different geological periods and analyzing the causes of tectonic deformations, and it is also the basis for tectonic restoration. However, since the paleo-tectonic stress field is already in the "past tense", especially for superimposed basins that have experienced multiple periods of tectonic movement, multiple periods of structural deformation are superimposed on each other, how to determine and identify each period of structural deformation, and how to accurately restore each period of tectonic movement The characteristics of the stress field have always been a difficult problem in the field of structural re...

AI Technical Summary

Problems solved by technology

① The structural trace method mainly judges the direction of the stress field of each structure in the development stage based on the relationship between typical structural trends such as faults, cracks, and folds and their combinations, and the direction of principal stress. Due to the superposition of structural deformation in the long term, a specific structure is not controlled by a single stress, so there are errors in the actual recovery process

④ The inversion method of fault slip data is based on the theory that the movement direction of the fault slip surface is parallel to the direction of the maximum shear stress on the fault surface (Jacques Angelier. Tectonic analysis off slip data sets [J]. Journal of Geophysical Research: Solid Earth 89. (B7), 1984: 5835-5848), although it is currently the most effective and widely used method to restore the paleo-tectonic stress field (Zhu Guang, Park Xuefeng, Zhang Zhang, et al. The evolution of the extension direction of the Hefei Basin and its dynamic mechanism[J ]. Geological Review, 2011, 57(2): 153-166), but this method is based on a large number of field sliding data measurements, and cannot be applied to the restoration of the paleostress field in the basin

Generally speaking, the existing paleo-stress field direction restoration techniques have their application limitations, and most of them are qualitative restoration. There is an urgent need for research on the quantitative restoration of the stress field direction in a key tectonic period underground in the basin.

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