Comprehensive characterization of pore and throat system for tight sandstone reservoirs and associated permeability determination method using SEM, rate-controlled mercury and high pressure mercury

Gao, Hui; Cao, Jie; Wang, Chen; He, Mengqing; Dou, Liangbin; Huang, Xing; Li, Tiantai

doi:10.1016/j.petrol.2018.11.043

Cited by 55 publications

(26 citation statements)

References 41 publications

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“…Hence, the intersect point of the two measurements was applied in this research as the connection point. As shown in Figure 7, the two sets of measurements of pore diameter distribution were plotted in the same figure, in which the intersection point was automatically determined as the connection point (Gao et al., 2019). Both measurements were truncated at the connection point and then the smaller pores from nitrogen adsorption measurements and the larger pores from the mercury invasion measurements are connected as the overall size distribution.…”

Section: Discussionmentioning

confidence: 99%

“…The MIP can be used to measure the pore throat radius quickly, pore throat distribution and other pore throat parameters, in which the measurement is more accurate with the higher mercury injection pressure. However, it is difficult to measure the micro-pore information due to the limited mercury injection pressure under laboratory conditions (Gao et al., 2019; Juliao et al., 2015; Wang et al., 2019). The LP-N 2 A technique can provide more particulars of the specific surface area and pore size of micro-pores, but the potential measurement errors from LP-N 2 A may also be magnified once the macro-pores are developed in the shale (Juliao et al., 2015; Wang et al., 2019).…”

Section: Introductionmentioning

confidence: 99%

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Comprehensive characterization of nano-pore system for Chang 7 shale oil reservoir in Ordos Basin

Gao

Cao

Wang

et al. 2020

Energy Exploration & Exploitation

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Detailed study on the pore structure of shale oil reservoir is significantly for the exploration and development, and the conventional single pore structure measurement method cannot accurately describe the pore structure characteristics of the shale oil reservoir. In this paper, the Field Emission Scanning Electron Microscope (FESEM), low-pressure nitrogen adsorption (LP-N2A) and mercury injection porosimetry (MIP) techniques are used to comprehensive evaluate the pore structure of Chang 7 shale oil reservoir. The FESEM results show that inter pores, inner pores, organic pores and micro-cracks are developed in Chang 7 shale oil reservoir, and the pore structure can be divided into two groups from the LP-N2A and MIP. A new pore structure comprehensive evaluation method was promoted according to the connection points from the pore sizes distribution curves of LP-N2A and MIP. With this comprehensive analysis of the pore size distribution, the pore size distribution of various shale samples feature as triple-peak pattern. Due to the heterogeneity of the shale oil samples, the corresponding pore apertures of the connection points are various, and the overall pore size distribution of shale oil reservoir samples can also be divided into two types. In Group I, the size distributions exhibited a bimodal feature in a narrow range from 1.71 to 100 nm. The trimodal feature of size distributions was captured in Group II with the pore diameter ranges from 1.71 to 1426.8 nm. Group I features smaller sorting coefficient and good pore connectivity. However, the trimodal corresponds to the complex pore structure and larger sorting coefficient for Group II.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comprehensive characterization of nano-pore system for Chang 7 shale oil reservoir in Ordos Basin

Gao

Cao

Wang

et al. 2020

Energy Exploration & Exploitation

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“…Generally, parameters including pore size, geometry and connectivity are quantified to characterize pore network structures of tight reservoirs, which can be obtained by using direct and indirect 2 of 20 techniques, such as thin section, MICP, SEM, NMR and X-ray computed tomography (X-ray µ-CT). Gao et al (2019) used SEM, rate-controlled mercury and high-pressure mercury to characterize the pore and throat system of tight sandstone reservoirs, and predicted the permeability of tight reservoirs [12]. Xiao et al (2017) combined SEM, rate-controlled mercury and NMR to investigate the pore throat structures and their evolutions [13].…”

Section: Introductionmentioning

confidence: 99%

Characterization of Pore Structures and Implications for Flow Transport Property of Tight Reservoirs: A Case Study of the Lucaogou Formation, Jimsar Sag, Junggar Basin, Northwestern China

Zhang

Liu

et al. 2021

Energies

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Quantitate characterization of pore structures is fundamental to elucidate fluid flow in the porous media. Pore structures of the Lucaogou Formation in the Jimsar Sag were investigated using petrography, mercury intrusion capillary porosimetry (MICP) and X-ray computed tomography (X-ray μ-CT). MICP analyses demonstrate that the pore topological structure is characterized by segmented fractal dimensions. Fractal dimension of small pores (r < Rapex) ranges from 2.05 to 2.37, whereas fractal dimension of large pores (r > Rapex) varies from 2.91 to 5.44, indicating that fractal theory is inappropriate for the topological characterization of large pores using MICP. Pore volume of tight reservoirs ranges over nine orders of magnitude (10−1–108 μm3), which follows a power-law distribution. Fractal dimensions of pores larger than a lower bound vary from 1.66 to 2.32. Their consistence with MICP results suggests that it is an appropriate indicator for the complex and heterogeneous pore network. Larger connected pores are primary conductive pathways regardless of lithologies. The storage capacity depends largely on pore complexity and heterogeneity, which is negatively correlated with fractal dimension of pore network. The less heterogeneous the pore network is, the higher storage capability it would have; however, the effect of pore network heterogeneity on the transport capability is much more complicated.

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“…The type and size of pores and cracks can be observed at various scales by means of preparation and identification of rock casting thin section, multiscale computed tomography (CT), scanning electron microscopy (SEM), field emission SEM (FESEM), and transmission electron microscopy (TEM) [9][10][11][12]. Gas adsorption, mercury porosimetry, nuclear magnetic resonance (NMR), and small-angle neutron scattering (SANS) can be used to quantitatively characterize the distribution range and frequency of pores and cracks [13,14]. The identification technology of rock casting thin section allows us to judge the mineral composition and pore distribution of rocks by means of microscopy, which is mainly used to observe the overall structure of rock surface and larger cracks or pores.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Hydration on Pores of Shale Oil Reservoirs in the Third Submember of the Triassic Chang 7 Member in Southern Ordos Basin

et al. 2019

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Shale oil is an unconventional kind of oil and gas resource with great potential. China has huge reserves of shale oil, and shale oil resources are abundant in the third submember of the Triassic Chang 7 member in the southern Ordos Basin. At present, this area is in the initial stage of shale oil exploration and development. The reservoir pore is one of the key factors affecting oil accumulation, drilling safety, and oil production. It is also an important reservoir parameter that must be defined in the exploration stage. In general, the clay content in the shale section is high, and is prone to hydration. In order to study the effect of fluid on the pore type, structure, and distribution of shale oil reservoirs, experiments using X-ray diffraction, a porosity-permeability test, mercury porosimetry, rock casting thin section, and scanning electron microscopy were carried out. The experimental results show that the content of clay and quartz is very high in the studied formation. The pore porosity and permeability of the rock is highly heterogeneous because of the obvious stratigraphic bedding and interbeds. Microstructural observation of rocks shows that the main pore types are intergranular pores, intragranular pores, intercrystalline pores, and organic pores. Crack types are dissolution cracks, contraction cracks of organic matter, and abnormal pressure structural cracks. After hydration, the porosity of rock will increase in varying degrees, and pore size, pore content in different sizes, and pore structure will also change. The results show that the pores of tuff mainly changes at the initial stage of hydration, and the pore change of tuff is the most obvious within 6 hours of soaking in clear water. The influence of hydration on the pore of shale is greater than that of tuff, but the main change stage is later than tuff, and the pore change of shale is the most obvious within 12 to 24 hours of soaking in clear water. The soaking experiment of water-based drilling fluid (WBM-SL) shows that it can plug a certain size of holes and cracks and form a protective layer on the rock surface, thus effectively reducing hydration. In actual construction, multisized solid particles should be allocated in drilling fluid according to the formation pore's characteristics, and the stability of the protective layer should be guaranteed. This can reduce the accident of well leakage and collapse and is conducive to the efficient and safe development of shale oil.

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Comprehensive characterization of pore and throat system for tight sandstone reservoirs and associated permeability determination method using SEM, rate-controlled mercury and high pressure mercury

Cited by 55 publications

References 41 publications

Comprehensive characterization of nano-pore system for Chang 7 shale oil reservoir in Ordos Basin

Comprehensive characterization of nano-pore system for Chang 7 shale oil reservoir in Ordos Basin

Characterization of Pore Structures and Implications for Flow Transport Property of Tight Reservoirs: A Case Study of the Lucaogou Formation, Jimsar Sag, Junggar Basin, Northwestern China

The Effect of Hydration on Pores of Shale Oil Reservoirs in the Third Submember of the Triassic Chang 7 Member in Southern Ordos Basin

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