Novel method for determining the oil moveable threshold and an innovative model for evaluating the oil content in shales

Wang, Enze; Li, Changrong; Yuan, Feng; Song, Yongli; Guo, Tonglou; Li, Maowen; Chen, Zhuoheng

doi:10.1016/j.energy.2021.121848

“…According to Figure 9, the correlation coefficients for BET-SSA are much worse than those of ISA. To understand these differences, it must be noted that the measured surface areas are the surface areas after the release of hydrocarbon or other confined fluid during coring and subsequent sample preservation (Jiang et al, 2016; Li et al, 2020;Wang et al, 2022). It has been demonstrated that free and physically adsorbed hydrocarbons or OM is mainly occurred on the outer surface, and they vaporize much easier and faster than chemically adsorbed hydrocarbons or OM which mainly occur on the inner surface (Jiang et al, 2016;Zhu et al, 2016).…”

Section: Surfacesmentioning

confidence: 99%

“…Furthermore, the flow properties are greatly affected by the fluid composition due to the divergences in the physical and chemical properties of different components and the interfacial interactions of different components with pore walls (Xu and Dehghanpour, 2014;Chen et al, 2016). Additionally, the fluid composition also changes along with the maturation of OM and the generation of lighter hydrocarbons, leading to the increase of the mobility of shale oil (Wang et al, 2022). Ion is the other chemical additive that is important for the efficient production of shale resources.…”

Section: Significances and Prospectsmentioning

confidence: 99%

“…Hydraulic fracturing is one of the most important technologies for the successful exploitation of unconventional oil and gas resources with ultra-low porosity and permeability, especially for shale resources (Osiptsov, 2017;Wang and Sheng, 2017;Lu et al, 2018;Aadnøy and Looyeh, 2019;Yang and Guo, 2019;Lu et al, 2020;Shi et al, 2020;Xie et al, 2020;Wang et al, 2022). One of the key concerns of the exploitation of shale resources is the evaluation of the production performance after fracturing (Jarvie et al, 2007;Wang and Gale, 2009;Jin et al, 2014;Tang et al, 2019;Wei et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Characteristics of Shale Pores and Surfaces and Their Potential Effects on the Fluid Flow From Shale Formation to Fractures

Li

¹

,

Cai

²

,

Gao

³

et al. 2021

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Fluid flow is critical for the efficient exploitation of shale resources and can be split into two stages: the flow in the artificial fractures and, more importantly, the flow from shale formations to the artificial fractures. In this study, X-ray diffraction, N2 adsorption, mercury intrusion, and ethylene glycol monoethyl ether adsorption were conducted on the shales collected from Es3middle, Es3lower, and Es4upper sub-members in the Dongying Sag to reveal the potential effects of the characteristics and properties of pores and surfaces on the fluid flow in shale formations. The results are indicated as follows: 1) The shales from Es3middle and Es3lower contain more I/S and detrital minerals but less illite and carbonate minerals than those of Es4upper. 2) The shales from Es3middle and Es3lower are mainly composed of smaller pores present in larger surface areas and lead to the steeper slope between the BrunauerEmmettTeller specific surface area (BET-SSA) and pore volumes. 3) Clay minerals mainly contribute to pore development, and carbonate minerals inhibit pore development. All kinds of surface areas (especially the inner surface area) are sourced by clay minerals, while I/S and illite present opposite effects. 4) Pore size and surface properties affect significantly the fluid flow in shale formations. The shales from Es4upper are the favorable interval for shale oil accumulation and flow, especially for the shales with depth ranges of 3360∼3410 m, which possess high carbonates, illite and total organic carbon content, low clay mineral content, large pore volume, high large pore content, and small surface areas. Additionally, fluid composition needs to be paid more concern in the future.

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“…The degree of thermal evolution is a vital factor for determining the resource potential of shale oil accumulations [28], and T max is one of the most commonly used parameters for evaluating the degree of thermal evolution [29]. Analysis of pyrolysis data T max (Figure 6) for the shale samples in the study area shows that the T max values are generally distributed in the range 410 to 460 °C.…”

Section: Mineral Composition and Lithofacies Divisionmentioning

confidence: 99%

Evaluation of the Oil-Bearing Properties of Shale and Shale Oil Mobility in the Fengcheng Formation in the Mahu Sag, Junggar Basin, Northwest China: A Case Study of Well Maye-1

He

¹

,

Zhong-liang

²

,

Qian

³

et al. 2022

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Due to an increasing energy demand and the depletion of conventional oil, there is ever increasing demand for unconventional shale oil and gas resources. As the most hydrocarbon-rich sag in the Junggar Basin, the development prospects for shale oil in the Mahu Sag have become a focus of research. However, so far, there have been few studies of the oil-bearing properties of shale and shale oil mobility in the sag. This paper redresses this using a range of methods, such as pyrolysis and multi-temperature step pyrolysis. The results show that the Fengcheng Formation shales are generally good quality source rocks. The main body of the shale is low mature-mature, and the type of organic matter is mostly Type II kerogen. In the depth intervals at 4616.45~4640.30 m, 4661.25~4695.20 m, 4728.30~4759.80 m, 4787.60~4812.30 m, and 4876.70~4940.25 m, the oil-bearing properties of the shale and shale oil mobility are good, with an average S 1 of more than 1.5 mg/g, OSI of more than 100 mg/g.TOC-1, a ratio of free/adsorbed oil ( S 1 − 1 + S 1 − 2 / S 2 − 1 ) of more than 3, and a ratio of free/total oil ( S 1 − 1 + S 1 − 2 / S 1 − 1 + S 1 − 2 + S 2 − 1 ) of more than 80%. The second member (P1f2) and the lower part of the first member (P1f1) of the formation offer the most promising commercial prospects. Shale oil mobility in the formation is greatly affected by the abundance of organic matter. The higher the TOC value, the greater the hydrocarbon generation capacity, and the better its adsorption capability in the shale. The Fengcheng Formation shale is mature, and shale oil mobility is good. Impacted by the main reservoir space, the felsic shale in the formation has optimal shale oil mobility, with the shale oil being characterized by self-generation and self-storage, and accumulation in adjacent layers.

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“…Due to the growing demand for fossil fuels, the petroleum industry has begun to search for these valuable resources at deeper depths and in unexpected locations (Bowker, 2007; Rexer, Beham, Aplin, & Thomas, 2013; Wang et al, 2019, 2021, 2022; Wang, Liu, Pang, Wu, et al, 2020; Zou et al, 2018). In general, clastic reservoir physical properties such as porosity and permeability decrease with increased distance from the surface (Taylor et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Micro‐ and nanoscale pore‐throat structure, fractal characteristics, and permeability estimation models in deep sandstones: Palaeogene Shahejie Formation, Nanpu Sag, NE China

Wang

¹

,

Yuan

²

,

Peng

³

et al. 2021

Self Cite

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Long‐term burial and strong diagenesis modification result in highly heterogeneous pore structures in deep clastic reservoirs; these heterogeneities exert a controlling influence over the development of these deep petroleum systems. A clear understanding of the pore structure simplifies the tasks of identifying and modelling reservoirs for the purposes of hydrocarbon exploration. This study characterizes the mineral compositions, physical properties, and pore systems of the first member of the Palaeogene Shahejie Formation (Es1) in the Nanpu Sag using thin section and scanning electron microscope observations, X‐ray diffraction measurements, mercury intrusion capillary pressure, and nuclear magnetic resonance data. Our results show that the Es1 sandstones typically fall into one of three different pore‐throat sizes: mainly 10 μm (type‐I), 1 μm (type‐II), and less than 1 μm (type‐III). Between type‐I and type‐III reservoirs, the pore system changes from residual intergranular pore (InterP) and secondary InterP to secondary intragranular pores (IntraP) and intercrystalline pores. The fractal theory is selected to quantify the heterogeneity of the pore‐throat structure, due to the existence of an irregular and complex pore system (IntraP and intercrystalline pores), the type‐III reservoir has the highest fractal dimension, which indicates that the complex pore‐throat structure is not conducive to the formation of high‐quality deep sandstone reservoirs. Using the fractal dimension and displacement pressure, a novel permeability prediction is proposed, compared with the previous method, the new model is simpler and more effective. Our research can deepen the geological understanding of deep‐burial sandstone reservoirs and further guide petroleum exploration.

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Novel method for determining the oil moveable threshold and an innovative model for evaluating the oil content in shales

Cited by 29 publications

References 35 publications

Characteristics of Shale Pores and Surfaces and Their Potential Effects on the Fluid Flow From Shale Formation to Fractures

Characteristics of Shale Pores and Surfaces and Their Potential Effects on the Fluid Flow From Shale Formation to Fractures

Evaluation of the Oil-Bearing Properties of Shale and Shale Oil Mobility in the Fengcheng Formation in the Mahu Sag, Junggar Basin, Northwest China: A Case Study of Well Maye-1

Micro‐ and nanoscale pore‐throat structure, fractal characteristics, and permeability estimation models in deep sandstones: Palaeogene Shahejie Formation, Nanpu Sag, NE China

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