Advanced fluid-typing methods for NMR logging

Xie, Ranhong; Xiao, Lizhi

doi:10.1007/s12182-011-0130-4

Cited by 21 publications

(6 citation statements)

References 7 publications

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“…Therefore, centrifugation can throw out the pore fluid whose pore radius is larger than a certain pore radius. It can get the amplitude at different pore radii. − …”

Section: Characteristics and Methodsmentioning

confidence: 99%

Effects of Microstructure and Rock Mineralogy on Movable Fluid Saturation in Tight Reservoirs

et al. 2020

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A large amount of injected fracturing fluid is retained in tight reservoirs, leading to low flowback efficiency (less than 30%). It may be related to low fluid movability in tight reservoirs, which is influenced by the complex pore structure and mineral composition. However, effects of microstructure and rock mineralogy on movable fluid saturation in tight reservoirs have not been studied clearly. The tight sandstone cores from the Ordos Basin, China, are analyzed by conducting a series of experiments, including routine petrophysical measurements and X-ray diffraction, scanning electronic microscopy, and nuclear magnetic resonance (NMR) experiments. The quantitative analysis of the pore structure is carried out based on the fractal theory. The results show that NMR T 2 distribution is divided into four types. For the T 2 spectrum (0 < β < 1) with a low left peak and a high right peak, the movable fluid saturation is 60.7% on average. Quartz has a positive correlation with movable fluid saturation, and clay minerals have a negative correlation with movable fluid saturation. It is caused by the high wettability of quartz and the strong cementation of clay minerals. Fractal dimension D mov has a negative correlation with movable fluid saturation. The complex structure and irregular shape of tight sandstone reduce the movable fluid saturation. Movable fluid mainly comes from macropores whose relaxation time is greater than 10 ms. In addition, the movable fluid porosity of the cores has obvious differences, especially in the macropores. Several studies have shown that the microscopic pore structure and mineral composition of tight sandstone are the key factors that determine the content of movable fluid in the tight reservoir.

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“…Therefore, centrifugation can throw out the pore fluid whose pore radius is larger than a certain pore radius. It can get the amplitude at different pore radii. − …”

Section: Characteristics and Methodsmentioning

confidence: 99%

Effects of Microstructure and Rock Mineralogy on Movable Fluid Saturation in Tight Reservoirs

et al. 2020

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“…Owing to double reformation by sedimentation and diagenesis, the sandstone of ultra-low permeability reservoir has a complex pore structure and is characterized by fluid occurrence in a unique state. Therefore, the quantitative evaluation and analysis of movable fluid saturation are of great significance when evaluating tight gas reservoirs (Hodgkins et al, 1999;Wang and Chen, 2008;Xie and Xiao, 2011;Yan et al, 2016Sheng et al, 2018. NMR experiments are carried out on ten samples from four layers in the study area (Table 4).…”

Section: Nmr Movable Fluid Testmentioning

confidence: 99%

Controlling Effects of Tight Reservoir Micropore Structures on Seepage Ability: A Case Study of the Upper Paleozoic of the Eastern Ordos Basin, China

Yang

et al. 2020

Acta Geologica Sinica (Eng)

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In this study, the types of micropores in a reservoir are analyzed using casting thin section (CTS) observation and scanning electron microscopy (SEM) experiments. The high-pressure mercury injection (HPMI) and constant-rate mercury injection (CRMI) experiments are performed to study the micropore structure of the reservoir. Nuclear magnetic resonance (NMR), gas-water relative seepage, and gas-water two-phase displacement studies are performed to examine the seepage ability and parameters of the reservoir, and further analyses are done to confirm the controlling effects of reservoir micropore structures on seepage ability. The experimental results show that Benxi, Taiyuan, Shanxi, and Shihezi formations in the study area are typical ultra-low porosity and ultra-low permeability reservoirs. Owing to compaction and later diagenetic transformation, they contain few primary pores. Secondary pores are the main pore types of reservoirs in the study area. Six main types of secondary pores are: intergranular dissolved pores, intragranular dissolved pores, lithic dissolved pores, intercrystalline dissolved pores, micropores, and microfracture. The results show that reservoirs with small pore-throat radius, medium displacement pressure, and large differences in pore-throat structures are present in the study area. The four types of micropore structures observed are: lower displacement pressure and fine pores with medium-fine throats, low displacement pressure and fine micropores with fine throats, medium displacement pressure and micropores with micro-fine throats, and high displacement pressure and micropores with micro throats. The micropore structure is complex, and the reservoir seepage ability is poor in the study areas. The movable fluid saturation, range of the gas-water two-phase seepage zone, and displacement types are the three parameters that well represent the reservoir seepage ability. According to the characteristic parameters of microscopic pore structure and seepage characteristics, the reservoirs in the study area are classified into four types (I-IV), and types I, II, and III are the main types observed. From type I to type IV, the displacement pressure increases, and the movable fluid saturation and gas-water two-phase seepage zone decrease, and the displacement type changes from the reticulation-uniform displacement to dendritic and snake like. Key words: micro-pore structure, seepage ability, movable fluid saturation, the range of gas-water two phase seepage zone, displacement types Citation: Yang et al., 2020. Controlling Effects of Tight Reservoir Micropore Structures on Seepage Ability: A Case Study of the Upper

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“…The ultralow-permeability sandstone reservoirs are jointly affected by the deposition and diagenesis, and feature complex microscopic pore structures and different fluid occurrences compared with the high-permeability reservoirs (Huyan et al 2018;Lai et al 2018a, b). Therefore, the quantitative evaluation of movable fluid saturation can represent the reservoir seepage capability to a certain degree and is crucial for the evaluation of ultralow-permeability reservoirs (Gao and Sun 2010;Gao et al , 2014Xie and Xiao 2011;Yang et al 2016;Lai et al 2018a, b).…”

Section: Characterization Of Reservoir Seepage Capability By Movable Fluid Saturationmentioning

confidence: 99%

The primary controlling parameters of porosity, permeability, and seepage capability of tight gas reservoirs: a case study on Upper Paleozoic Formation in the eastern Ordos Basin, Northern China

Yang

Tian

et al. 2019

Pet. Sci.

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Tight sandstone gas (hereafter “tight gas”) has become a subject of unconventional gas exploration globally. The large-scale development and use of tight gas resources in the USA, in particular, facilitated the rapid rebound of natural gas production in the USA, in addition to driving the rapid development of tight gas worldwide. In the eastern Ordos Basin, the Upper Paleozoic feature includes multiple layers of gas, a shallow depth, and notable potential for exploration and development. However, the reservoirs in the area are relatively tight, exhibit strong heterogeneity, and possess a complex micropore structure, thus restricting the effective economic development of oil and gas. Thus, research on the primary parameters controlling pore throat structure and the seepage capability of low-permeability reservoirs will be beneficial for the efficient exploration and development of natural gas in the eastern Ordos Basin. The parameters of reservoir porosity and percolation ability, as well as permeability, were analyzed using systematic sampling of the of the Upper Paleozoic Benxi, Taiyuan, and Shanxi Formations in the eastern Ordos Basin, constant-rate mercury injection experiments, nuclear magnetic resonance analysis, and gas–water-phase experimental studies. The results indicate that reservoir porosity is controlled by the effective pore volume and number, whereas permeability is controlled by the largest throat radius, rather than the average. The effective pore volume controls the movable fluid saturation, while reservoir percolation capability is controlled by the effective pore volume, irreducible water saturation, and size of the gas–water two-phase seepage zone.

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Advanced fluid-typing methods for NMR logging

Cited by 21 publications

References 7 publications

Effects of Microstructure and Rock Mineralogy on Movable Fluid Saturation in Tight Reservoirs

Effects of Microstructure and Rock Mineralogy on Movable Fluid Saturation in Tight Reservoirs

Controlling Effects of Tight Reservoir Micropore Structures on Seepage Ability: A Case Study of the Upper Paleozoic of the Eastern Ordos Basin, China

The primary controlling parameters of porosity, permeability, and seepage capability of tight gas reservoirs: a case study on Upper Paleozoic Formation in the eastern Ordos Basin, Northern China

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