Continental lake basin tight reservoir pore throat effectiveness quantitative evaluation method under geological conditions

Abstract

The invention provides a continental lake basin tight reservoir pore throat effectiveness quantitative evaluation method under geological conditions. The method comprises the following steps: establishing a relational expression between nuclear magnetic resonance signal intensity and porosity; measuring a T2 spectrum of a to-be-measured reservoir rock core after saturated water treatment in a normal-pressure environment; sequentially applying confining pressure with different pressure values to the to-be-measured reservoir rock core after saturated water treatment to simulate the pressure-bearing change condition of a rock pore structure in the stratum burying process, and respectively measuring T2 spectra of the to-be-measured reservoir rock core after saturated water treatment under theconfining pressure with different pressure values; and according to the measured T2 spectra and the established relational expression between the nuclear magnetic resonance signal intensity and the porosity, determining the pore diameter-porosity distribution of the to-be-measured reservoir rock core under different pressure values, and quantitatively evaluating the change of different-scale effective pore throats of the tight reservoir under geological conditions, thereby realizing the quantitative evaluation of the effectiveness of different-scale pore throats of the continental lake basin tight reservoir under geological conditions.

Description

technical field [0001] The invention relates to a method for evaluating the oil content of tight reservoirs in continental lake basins, in particular to a method for quantitatively evaluating the oil content of connected and unconnected pores of tight reservoirs. Background technique [0002] In recent years, tight (shale) oil resources, as a replacement resource for conventional oil fields, have gradually become a hot spot for increasing global oil reserves and production. Tight oil reservoirs develop complex nano-micron multi-scale pore-throat systems (Zou Cai, Zhu Rukai, Bai Bin et al. The first discovery of nano-pore throats in oil and gas reservoirs in China and its scientific value[J]. Acta Petrologie Sinica, 2011, 27( 6): 857-1864). Compared with conventional oil and gas, which pays more attention to the matching relationship of "six elements", the fine research and quantitative evaluation of the microscopic pore-throat structure characteristics of reservoirs are the...

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Problems solved by technology

Many studies have shown that changes in temperature and pressure conditions in the process of deposition, diagenesis, and maturity evolution have affected and transformed the pore-throat structure characteristics of reservoirs (Jiang Zaixing, Zhang Wenzhao, Liang Chao, etc. Basic characteristics of shale oil reservoirs and Evaluation elements[J]. Acta Petroleum Sinica, 2014,35(1):184-196; Cui Jingwei, Zhu Rukai, Cui Jinggang. Shale pore evolution and its relationship with residual hydrocarbon: Evidence from simulation experiments under the constraints of geological processes[J] ]. Acta Geological Sinica, 2013, 87(5): 730-736; Zhang Linye, Bao Youshu, Li Juyuan, etc. Mobility of lacustrine shale oil—a case study of Dongying Sag, Jiyang Depression, Bohai Bay Basin[J ].Petroleum Exploration and Development 2014,41(6):641-649), the analysis and measurement by changing the charging pressure without considering the temperature and pressure conditions cannot satisfy the accurate evaluation of the real microscopic pore-throat structure of tight (shale)

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