Investigation of Organic Related Pores in Unconventional Reservoir and Its Quantitative Evaluation

Ge, Xin; Fan, Yiren; Cao, Yingchang; Li, Jiangtao; Cai, Jianchao; Liu, Jianyu; Wei, Sudong

doi:10.1021/acs.energyfuels.6b00590

Cited by 53 publications

(29 citation statements)

References 29 publications

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“…It is well known that reservoirs are considered water-wet initially. When the reservoir gradually becomes oil-wet, its resistivity is abnormally high relative to that of the same water-wet one (Tiab and Donaldson, 1996), and the NMR T 2 spectra can not reflect pore structure (Wang and Li, 2009;Ge et al, 2016). On the basis of the above understandings, typical core samples with abnormally high resistivity and normal resistivity were selected for petrophysical experiments, and then thin slices were cut from some core samples to measure contact angle.…”

Section: Methodsmentioning

confidence: 99%

An Experimental Study on Resistivity and Conductive Mechanism in Low‐permeability Reservoirs With Complex Wettability

Cheng

Mao

Yin

et al. 2017

Chinese J of Geophysics

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As the clay film developed in low-permeability lithologic reservoirs absorbs oil, reservoirs become oil-wet, which results in abnormally high resistivity oil-water layers and water layers. Such layers bring great challenges to the identification of oil and water layers. In order to make clear the resistivity response characteristics and conductive mechanism in reservoirs with different wettability, cores were selected in Chang 8 formation, Yanchang group, Upper Triassic, the western Ordos basin of China. Experiments were conducted with these samples to simulate the process of oil displacing water, ageing and water displacing oil. In addition, the contact angles of thin slices after washing oil were also tested. The experimental results show that abnormally high resistivity cores are not completely water-wet after washing oil. However, the formation factors of abnormally high resistivity cores and normal resistivity cores have little difference. In the process of oil displacing water, the relationship between normal resistivity core resistivity index and water saturation is linear in a log-log plot, while that of abnormally high resistivity cores is convex. The resistivity of abnormally high resistivity cores remains unchanged during ageing process. Combining the analysis of nuclear magnetic resonance (NMR) T2 spectra under different conditions, it can be inferred that wettability of abnormally high resistivity cores has become less waterwet after oil displacing water, whereas the ageing process has little effect on the wettability. In the process of water displacing oil, the relation between abnormally high resistivity core resistivity index and water saturation is almost linear, which shows that the conductive structure of rock is not changed. Based on the analyses and discussions of these experimental results, a hydrocarbon accumulation mode and the corresponding conductive mechanism are proposed for low-permeability reservoirs with complex wettability. It shows that abnormally high resistivity water layers are caused by the destruction of continuous conductive paths under oil-wet condition. The researches and experiments are of great importance for understanding the conductive mechanism, identifying oil and water layers and evaluating water flooded formations in low-permeability reservoirs with complex wettability.

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Section: Methodsmentioning

confidence: 99%

An Experimental Study on Resistivity and Conductive Mechanism in Low‐permeability Reservoirs With Complex Wettability

Cheng

Mao

Yin

et al. 2017

Chinese J of Geophysics

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“…8,9 With the improvement and development of experimental methods, research of microscopic pore structures in reservoirs has gradually transitioned from basic physical analysis to advanced experimental tests and methods. [18][19][20] Ideal results cannot be achieved by a single technological method because of the lithology of tight oil reservoirs, diversity, and heterogeneity of rock pores and the limitation of experimental methods. However, each technique has advantages and disadvantages.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, high-pressure mercury injection experiments require drying of the samples, which alters the porosity, permeability, and fabric of samples with high clay contents. [18][19][20] Ideal results cannot be achieved by a single technological method because of the lithology of tight oil reservoirs, diversity, and heterogeneity of rock pores and the limitation of experimental methods. 21,22 Although there has been much research characterizing the pore structure of tight oil reservoirs, the contribution of different pore throat types toward the reservoir accumulation capacity and producing degree has been ignored for the most part.…”

Section: Introductionmentioning

confidence: 99%

Influence of micro‐pore structure in tight sandstone reservoir on the seepage and water‐drive producing mechanism—a case study from Chang 6 reservoir in Huaqing area of Ordos basin

Ren

et al. 2019

Energy Science & Engineering

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To study the influence of pore structure on the seepage and water‐drive producing mechanisms, various methods were combined to describe the micro‐pore structure in the Chang 6 tight sandstone reservoir in the Huaqing area, Ordos Basin, China. Nuclear magnetic resonance (NMR) was combined with displacement experiments to determine the distribution of oil and water in pores of different scales before and after water flooding. There are few micro pores in the reservoir. As permeability increases, the distribution of nano pores decreases, while sub‐micro pores increase. Also, sub‐micro pores are the main pathway within the reservoir. There is a negative power function correlation between the minimum starting pressure gradient of the oil (Swc) and maximum throat radius. Also, with a decrease of permeability, smaller pore throats become more abundant and the nonlinear section of the flow velocity‐differential pressure curves increase. There is a large amount of crude oil gathering in the nano pores. As permeability increases, the main sources of movable oil are from the nano pores (kg < 0.4 × 10−3 μm2), sub‐micro pores (kg ≈ 0.4 × 10−3 μm2‐1.0 × 10−3 μm2), and micro pores (kg > 1.0 × 10−3 μm2). Displacement efficiency is always the highest in sub‐micro pores.

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“…Recently, El-Amin et al [5] used the dual-porosity dual-permeability model with geomechanical effect. Ge et al [6] presented a quantitative evaluation for organic related pores in unconventional reservoir. A comprehensive review has been introduced on gas transport in tight and shale formations was done by Salama et al [7].…”

Section: Introductionmentioning

confidence: 99%

Mixed Finite Element Solution for the Natural-Gas Dual-Mechanism Model

El-Amin

Kou

Sun

et al. 2019

Lecture Notes in Computer Science

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The present work is dedicated to studying the transfer of natural gas in shale formations. The governing model was developed on the basis of the model of dual-porosity dual-permeability (DPDP). The mixed finite element method (MFEM) is employed to solve the governing equations numerically. Numerical example is presented and results discussed such as production cumulative rate, pressure and apparent permeability.

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Investigation of Organic Related Pores in Unconventional Reservoir and Its Quantitative Evaluation

Cited by 53 publications

References 29 publications

An Experimental Study on Resistivity and Conductive Mechanism in Low‐permeability Reservoirs With Complex Wettability

An Experimental Study on Resistivity and Conductive Mechanism in Low‐permeability Reservoirs With Complex Wettability

Influence of micro‐pore structure in tight sandstone reservoir on the seepage and water‐drive producing mechanism—a case study from Chang 6 reservoir in Huaqing area of Ordos basin

Mixed Finite Element Solution for the Natural-Gas Dual-Mechanism Model

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