Pore movability classification and evaluation method for tight sand reservoir

Abstract

The invention relates to a pore movability classification and evaluation method for a tight sand reservoir. The pore movability classification and evaluation method for the tight sand reservoir comprises the specific steps of: S1, preparing a sample, and carrying out nuclear magnetic resonance and high-pressure mercury injection test on the sample; S2, drawing a mercury injection curve, a Pittmancurve and a fractal curve according to a mercury inlet saturation and a mercury inlet pressure Pc, determining boundaries of intergranular pores and intragranular pores according to a boundary of a platform section and an increasing section of the mercury injection curve, a vertex of the Pittman curve and a turning point of the fractal curve, and dividing into the intergranular pores and the intragranular pores according to the boundaries; S3, according to a relationship between a saturated water nuclear magnetic curve and a bound water nuclear magnetic curve, by combining the boundaries of the intergranular pores and the intragranular pores, dividing the intergranular pores into movable large pores and isolated large pores and dividing the intragranular pores into movable micro pores andunmovable micro pores; and S4, calculating content of different types of pores. According to the invention, evaluation on movability of different types of pores of the tight sand reservoir can be implemented, movability evaluation of the pores of the reservoir further accords with the actual geological condition, and an evaluation result is more accurate.

Description

technical field [0001] The invention belongs to the technical field of oil and gas geological exploration, and in particular relates to a method for classifying and evaluating the mobility of pores in tight sandstone reservoirs. Background technique [0002] Tight sandstone reservoirs have multiple pore types such as residual intergranular pores, dissolution pores, and clay intercrystalline pores (see: Zhao et al., 2015; Gao et al., 2016; Lai et al., 2017, 2018), among which There are large differences in size, distribution and connectivity (see A. Sakhaee-Pour and Steven L. Bryant, 2014; Xiao Dianshi et al., 2017). The complex pore-throat network of tight reservoirs has a particularly obvious impact on reservoir properties, especially permeability (see Zhao et al., 2015; Lai et al., 2016, 2018; Schmitt M et al., 2015), and its controlling role It mainly depends on the development of movable pores in the pore system (see Xi et al., 2016; Huang et al., 2018). Generally, in ...

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Problems solved by technology

For example, Wu Hao et al. (2015), Li Min et al. (2018), Shi Jianchao et al. (2016), Dai Quanqi et al. (2016), Huang et al. (2018), Li et al. (2018), Wu Yuping et al. (2019) passed The nuclear magnetic resonance technology obtains the parameters such as the saturation of movable fluid and the porosity of movable fluid in tight reservoirs, and uses the above parameters to evaluate the mobility of tight reservoirs, and to study the mobility and influencing factors of different types of reservoirs. Mobility of different types of pores has not been studied

[0004] It can be seen from the above that the current evaluation of the pore mobility of tight sandstone reservoirs mostly relies on the parameters such as the movable fluid saturation and movable fluid porosity obtained by nuclear magnetic resonance technology. The characterization of the mobility of different types of pores in tight reservoirs affects the understanding of the development of movable pores in tight reservoirs and reduces the success rate of tight oil and gas exploration and development

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