High-precision calculation of gas saturation in organic shale pores using an intelligent fusion algorithm and a multi-mineral model

Zhu, Linqi; Zhang, Chaomo; Zhang, Zhansong; Zhou, Xueqing

doi:10.26804/ager.2020.02.03

Cited by 31 publications

(12 citation statements)

References 33 publications

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“…The pore characteristics of the shales can be directly observed with an SEM. As is shown in the FIB-SEM images, the largest greyscale is the pore, while the greyscale of every material composition in the shales becomes lower as its molecular weight is smaller (Zhang et al, 2019b;Zhang et al, 2019c;Wang et al, 2020b;Xia et al, 2020;Zhu et al, 2020; Huang Wang et al, 2021), indicating that the grey scale of organic matter in the FIB-SEM images is larger than the one of inorganic minerals. It can be seen from the FIB-SEM images A and B of Figure 4 that a large number of organic matter pores are developed in the shales with excellent roundness.…”

Section: Fib-sem Observationmentioning

confidence: 95%

Study on the State of Methane Molecule Adsorption on Different Media in Highly Evolved Marine Shales—A Case Study on the Shales From the Lower Silurian Longmaxi Formation in the Sichuan Basin, Southern China

Jiang

Song

Liu³

et al. 2022

Front. Earth Sci.

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The major sedimentary basins in China contain abundant shale gas resources to be explored, and the exploration of shale gas has received more attention in recent years. Shale gas exists mainly in two states, i.e., free and adsorbed. The latter mainly exists on the surface of media, including organic matter and clay minerals, etc., but its adsorption state remains unknown. In this paper, we take the Longmaxi Formation marine shale in the southern Sichuan Basin of southern China as the research object. The state of methane molecule adsorption on different media in marine shales is analyzed by conducting mineral composition analysis, TOC content analysis, isothermal adsorption experiments, FIB-SEM, and FIB-HIM experiments on the core samples referring to previous research. The conclusions are as follows: the adsorbed gas mainly exists in the organic-matter pores, which feature excellent roundness and connectivity with a large number of small pores inside like a hive. The surface of the organic matter contains many adsorption sites, featuring strong adsorption capacity and making methane molecules continuously distributed on the internal surface of the organic-matter pores. The organic matter has a large specific surface area and is lipophilic, which offers an ideal condition for the adsorption of methane molecules. Part of the adsorbed gas exists in the pores of clay minerals, which are lamellar and triangular. The surface of clay minerals contains fewer adsorption sites, featuring poorer adsorption capacity and making methane molecules discontinuously distributed on the surface of the clay minerals. The clay minerals have a smaller specific surface area than the organic matter, thus featuring a smaller space for adsorption. The clay minerals are hydrophilic. In addition to methane molecules, mixed-layer illite/smectite (I/S) and chlorite also adsorb water molecules. The illite surface adsorbs mainly water molecules and, to a lesser extent, methane molecules. Finally, the adsorption state patterns of methane molecules on organic matter and clay minerals were summarized.

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Section: Fib-sem Observationmentioning

confidence: 95%

Study on the State of Methane Molecule Adsorption on Different Media in Highly Evolved Marine Shales—A Case Study on the Shales From the Lower Silurian Longmaxi Formation in the Sichuan Basin, Southern China

Jiang

Song

Liu³

et al. 2022

Front. Earth Sci.

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“…Following the commencement of the high water cut period, it is observed in laboratory experiments and on-site manufacturing procedures. Conventional water flooding's typical curve will deflect, leading to phenomena such as downward bending and upward warping [4][5][6]. At the moment, the straight-line section of the traditional water flooding characteristic curve is still utilized to estimate that the target reservoir's development index and recoverable reserves will have bigger inaccuracies.…”

Section: Introductionmentioning

confidence: 99%

Application of New Water Flooding Characteristic Curve in the High Water-Cut Stage of an Oilfield

Zhang¹,

Wang²,

Wang³

et al. 2022

Fluid Dynamics &Amp; Materials Processing

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The oil production predicted by means of the conventional water-drive characteristic curve is typically affected by large deviations with respect to the actual value when the so-called high water-cut stage is entered. In order to solve this problem, a new characteristic relationship between the relative permeability ratio and the average water saturation is proposed. By comparing the outcomes of different matching methods, it is verified that it can well reflect the variation characteristics of the relative permeability ratio curve. Combining the new formula with a reservoir engineering method, two new formulas are derived for the water flooding characteristic curve in the high water-cut stage. Their practicability is verified by using the production data of Mawangmiao and Xijiakou blocks. The results show that the error between the predicted cumulative oil production and production data of the two new water drive characteristic curves is less than the error between the B-type water drive characteristic curve and the other two water drive characteristic curves. It is concluded that the two new characteristic curves can be used to estimate more accurately the recoverable reserves, the final recovery and to estimate the effects of water flooding. KEYWORDSWater flooding characteristic curve; high water cut period; production dynamic prediction; recoverable reserves; water flooding Nomenclature WOR Water-oil ratio; Q w Water production, t/day; Q o Oil production, t/day; K rw , K ro Relative permeability of water phase and oil phase; μ w , μ o Water, oil viscosity, mPa⋅s; B w , B o Water and oil volume coefficient, m 3 /m 3 ; a, b, c Constants influenced by reservoir and fluid properties; A, B, C, C 1 Constants; S w Water saturation, %; S w Average water saturation, %; S we Outlet end water saturation;

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“…Especially, Archie's equation cannot handle the core samples with tight pore structures such as shale. Hence, many scientists have studied variety types of analytic models to explain the gaps between well logs and core data to estimate accurate total organic contents (TOC) and water saturation [2,3].…”

Section: Introductionmentioning

confidence: 99%

Estimation of Water Saturation in Shale Formation Using In Situ Multifrequency Dielectric Permittivity

et al. 2022

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Estimating water saturation via conventional logging tool such as resistivity cannot provide an accurate solution in a formation with low conductivity water and tight porosity. As an alternative, we employed a dielectric permittivity, which makes it easy to differentiate the water from the other fluids in pore structures. A multichannel frequency dielectric logging tool is used for measuring in situ permittivity. To simulate a dielectric permittivity, we used two analytic models: Lichtenecker-Rother (LR) and Stroud-Milton-De (SMD) models. The key goal of this research is to propose a workflow to evaluate an equivalent Archie’s parameter which can generate the same dielectric logging tool responses with core measurement results using a given analytic models. According to the results of the LR model curve-fitting, the estimated Archie’s parameter shows inversely proportional relationship with clay volumes. The estimated Archie’s parameter from the SMD model is sensitive to the lower frequency channels of the multifrequency dielectric logging tool. Nevertheless, utilizing the response of the dielectric logging tool in the frequency range, where interfacial polarization effect does not exist, can provide an alternative to estimate water saturation in shale formations with relatively less conductive waters.

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High-precision calculation of gas saturation in organic shale pores using an intelligent fusion algorithm and a multi-mineral model

Abstract: High-precision calculation of gas saturation in organic shale pores using an intelligent fusion algorithm and a multi-mineral model. Advances in

Cited by 31 publications

References 33 publications

Study on the State of Methane Molecule Adsorption on Different Media in Highly Evolved Marine Shales—A Case Study on the Shales From the Lower Silurian Longmaxi Formation in the Sichuan Basin, Southern China

Study on the State of Methane Molecule Adsorption on Different Media in Highly Evolved Marine Shales—A Case Study on the Shales From the Lower Silurian Longmaxi Formation in the Sichuan Basin, Southern China

Application of New Water Flooding Characteristic Curve in the High Water-Cut Stage of an Oilfield

Estimation of Water Saturation in Shale Formation Using In Situ Multifrequency Dielectric Permittivity

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