A method to quantitatively determine the critical condition of brittleness and ductility of gypsum-carbonate rock

Abstract

The invention provides a method for quantitatively determining the brittle-ductile critical condition of gypsum rock-carbonatite. The method comprises the steps that the gypsum rock-carbonatite is adopted as a sample, and the sample comprises the lithological characters of gypsum containing dolomite, gypseous dolomite, dolomite-quality gypsum rock and dolomite containing gypsum rock; temperature and pressure of a critical construction period of petroleum entrapment evolution according to the history of structural evolution of a basin where the gypsum rock-carbonatite is located, and are adopted as temperature and pressure of experimental simulation; the maximum differential stress value and the maximum inflection point stress point of the sample are measured under simulation temperature and pressure respectively; the critical position of conversion of the brittleness and tenacity of the sample is quantitatively evaluated according to the maximum differential stress value and the maximum inflection point stress point of the sample, and the brittle-ductile critical condition of the gypsum rock-carbonatite is quantitatively determined. According to the method, the brittle-ductile critical condition of the gypsum rock-carbonatite can be accurately evaluated, and a basis is provided for accurately evaluating and predicting petroleum entrapment of the gypsum rock-carbonatite.

Description

technical field [0001] The invention relates to a method for quantitatively determining the petrophysical property conversion conditions of brittleness and toughness of gypsum carbonate rock under the constraints of geological conditions, and belongs to the technical field of petroleum geological research. Background technique [0002] With the successful development of ancient carbonate rock oil and gas in the world, the gypsum-salt rock-carbonate rock symbiosis system similar to the Permian sub-salt in the Pre-Caspian Basin in Central Asia has shown huge oil and gas potential, forming the world's largest oil and gas fields. [0003] However, the hydrocarbon accumulation process in the gypsum-carbonate rock paragenetic assemblage is still not very clear, especially in the hydrocarbon accumulation process of gypsum rock, the traditional view is that it mostly acts as a capping oil and gas (Jin Zhijun, Zhou Yan, Yun Jin Biao et al. Distribution of gypsum-salt cap rocks in mar...

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Problems solved by technology

[0005] However, there are few studies on whether gypsum rock has other functions in the hydrocarbon accumulation process of carbonate rocks, especially in the process of basin burial or uplift, due to the difference in temperature and pressure environment of gypsum rock, its effect on carbonate There are few studies on the role of rock oil and gas accumulation, and more qualitative speculations exist in rock physical states of plasticity and brittleness

At the same time, for the gypsum-carbonate paragenetic assemblages of different lithologies, there are still few studies on the temperature and pressure conditions for quantitative evaluation of their brittle-ductile transformation, especially the brittle-ductile characteristics under different temperature and pressure conditions have great influence on oil and gas accumulation. less impact research

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