Characteristics of in-situ stress and its controls on coalbed methane development in the southeastern Qinshui Basin, North China

Cao, Lutong; Yao, Yanbin; Cui, Chao; Sun, Qian

doi:10.1016/j.engeos.2020.05.003

Cited by 28 publications

(15 citation statements)

References 24 publications

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“…It had a great frequency of collision between coal fine particles and the surface of fractures at high velocity that had a high sediment rate . Therefore, in the process of CBM drainage, the water production rate should be reasonably controlled according to the permeability, which avoids a large amount of coal fines migration and precipitation caused by rapid drainage. , The variation characteristics of permeability loss with time with the decrease of coal fines sizes were complex. The permeability loss with the time displayed a gradually increasing trend for an injection flow rate less than 5 mL/min with a decrease of particle size.…”

Section: Resultsmentioning

confidence: 99%

Coal Fines Migration, Deposition, and Output Simulation during Drainage Stage in Coalbed Methane Production

Han

Wang

et al. 2021

Energy Fuels

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Fracture and cleats development controls the permeability of coal reservoirs, while the migration of coal fines can block fractures and affect coalbed methane (CBM) production performance. To reveal the migration, agglomeration, and settlement of coal fines within fractures, and also to investigate permeability variations, an experimental simulation was conducted. Factors like coal fine particle sizes (<48, 48−75, 75−96, 96−120, and 120−180 μm), fracture width (0.05, 0.10, 0.15, and 0.20 mm), coal fines suspension concentration (0.5‰, 1.0‰, 1.5‰, 2.0‰, and 2.5‰), and injection flow rates (2.5, 5.0, 7.5, and 10.0 mL/min) were considered, and the deposited and output coal fines qualities were recorded. The results showed that by controlling stable injection flow rates, the injection pressures increased with the extension of time, indicating fractures were blocked gradually by coal fines. The pressure variation curves could be divided into three types: (1) steady slow rise type, (2) stable to sharp rise type, and (3) fluctuating type. The quality of deposited coal fines in fractures varied between 0.0068 and 0.917 g, and the quality of output coal fines was between 0 and 0.1028 g. With fracture width incrementation, the deposited and output values of coal fines of different sizes all increased. As coal fines concentration increased, the output values first increased and then decreased, and vice versa for deposited values. When the injection flow rate increased, the deposited coal fines values initially increased and then diminished. In the largest coal fines deposition, an injection flow rate of 5.0 mL/min was observed, while larger and stable coal fines migration and production were observed at 2.5 and 7.5 mL/min. Under most of the circumstances (except for 120−180 μm coal fines), permeability losses were concentrated between 70% and 95%, and the permeability loss with time was concentrated between 0.15 and 0.178 mD/h. Thus, the induced damages of coal fines to fractures were similar and could damage most of the flow channels. The quality of deposited coal fines was positively correlated with permeability reduction. For better coal fines output during CBM production, the flow rate should be controlled at certain rates for stable coal fines migration (e.g., 7.5 mL/min in this study). Also, further research should be focused on the dispersion of coal fines and their precise control.

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Section: Resultsmentioning

confidence: 99%

Coal Fines Migration, Deposition, and Output Simulation during Drainage Stage in Coalbed Methane Production

Han

Wang

et al. 2021

Energy Fuels

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“…Many kinds of ions and minerals are dissolved in the pore fluid, and when their content reaches a supersaturated state, they will precipitate in the pores and consolidate to form rock (Cao, Yao, Cui, & Sun, 2020;Chang, Wang, Shi, & Xu, 2019). This process is called cementation.…”

Section: Cementationmentioning

confidence: 99%

Diagenesis and reservoir classification criteria for Jurassic continental sandstone oil reservoir in the western Ordos Basin, China

Wei

Chen

et al. 2021

Geological Journal

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The marginal area of a sedimentary basin is closer to the provenance, so the sand body is generally more developed. For the Western Margin Thrust Belt of the Ordos Basin, the quality of the Jurassic sandstone reservoirs is still less studied. Diagenesis and reservoir evaluation are important research contents and hotspots in sedimentary geology. Therefore, in this paper, the diagenesis and reservoir properties of the Jurassic Yan 6 to Yan 10 members (Yan'an Formation) have been systematically studied based on the latest 3D seismic, well logging, cast thin section, scanning electron microscope and petrophysical property tests in this area. Furthermore, the vertical heterogeneity of petrophysical properties of the Jurassic reservoir has been discussed in detail, and the diagenetic evolution sequence and classification criteria of Jurassic sandstone reservoir have been proposed. The research results show that the lithologies of the Yan 6 to Yan 10 members are mainly lithic quartz sandstone, lithic feldspar sandstone and feldspar lithic sandstone. The pore types of sandstone are mainly intergranular pores, followed by dissolution pores, intercrystalline pores and a few microfractures. There are two high-value porosity zones in the buried depths of 1,950-2,050 m and 2,150-2,250 m, which are the coupling results of dissolution and palaeo-overpressure. Based on the comprehensive study of petrology, petrophysical properties and diagenesis, the diagenetic evolution sequence of the Jurassic sandstone was restored and a comprehensive classification standard for the Jurassic sandstone reservoirs is proposed. The Jurassic reservoir in the study area is a structurallithological reservoir, which has a unified oil-water interface, the Type I and Type II reservoir areas in the structural high positions are conducive to the large-scale accumulation of hydrocarbons.

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“…Fractured reservoirs have strong heterogeneity, so traditional fracture evaluation methods face many challenges, such as the fine identifications of fractured segments and fracture sweet spots of tight reservoirs based on geophysical methods (Baecher., 1983;Bhatti et al, 2020;Chen., 2020;Fan et al, 2020a;Han et al, 2021;Liu et al, 2021a). At present, the conventional methods for identifying and evaluating reservoir fractures include core observations, conventional and imaging logging (Dowd et al, 2007;Casini et al, 2016;Li et al, 2019;Cao et al, 2020;Fan et al, 2020b;Liu et al, 2020a;Bukar et al, 2021). The cores obtained by drilling can be used to directly observe the development of underground fractures (Dcrshowitz and Einstein., 1988;Li et al, 2021;Yang et al, 2021;Xu and Gao., 2020;Nakaya and Nakamura., 2007;Dong et al, 2018;Hong et al, 2020;Liu et al, 2020b;Liu et al, 2021b).…”

Section: Introductionmentioning

confidence: 99%

Development Characteristics and Finite Element Simulation of Fractures in Tight Oil Sandstone Reservoirs of Yanchang Formation in Western Ordos Basin

Wang

et al. 2022

Front. Earth Sci.

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Structural fractures have a significant control effect on the large-scale accumulation of hydrocarbons in the Yanchang Formation. Previous studies have affirmed the important role of fractures in hydrocarbon accumulations in strongly deformed zones. However, for low-amplitude structural areas, the degree of fracture development is relatively low, and their control on sweet spots of hydrocarbons has not yet formed a unified understanding. In this paper, taking the Upper Triassic Yanchang Formation in the western Ordos Basin as an example, the development characteristics, prediction method, and the distribution of fractures in tight sandstone reservoirs in low-amplitude structural areas have been systematically studied using a large number of cores, thin sections, paleomagnetism, FMI logging, acoustic emission, productivity data, and finite element method. The research results showed that the Yanchang Formation in the study area mainly develop high-angle and vertical fractures, which were formed by regional tectonic shearing. Fractures are mainly developed in the fine-grained and ultra-fine-grained sandstones of the distributary channel and estuary bar microfacies, while the fractures in the medium-grained sandstones of the distributary channel and the mudstones of the distributary bay are relatively underdeveloped. The core fractures and micro-fractures of the Yanchang Formation all have the regional distribution characteristics, and the fracture strikes are mainly between NE50° and NE 70°. Moreover, the finite element method was used to predict the fractures in the target layer, and the prediction results are consistent with the actual distribution results of the fractures. The coupling analysis of fractures and tight oil sandstone distribution showed that the existence of fractures provided conditions for the accumulation of hydrocarbons in the Yanchang Formation. The confluence and turning areas of the river channels were repeatedly scoured by river water, and the rocks were brittle and easy to form fractures. The thickness of the fractured sandstone in these areas is usually greater than 0.4 m. Moderately developed fracture zones are prone to form hydrocarbon accumulation “sweet spots,” and the fracture indexes of these areas are usually distributed between 0.8 and 1.2. However, when the fracture index exceeds 1.2, over-developed fractures are unfavorable for the accumulation of hydrocarbons.

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Characteristics of in-situ stress and its controls on coalbed methane development in the southeastern Qinshui Basin, North China

Cited by 28 publications

References 24 publications

Coal Fines Migration, Deposition, and Output Simulation during Drainage Stage in Coalbed Methane Production

Coal Fines Migration, Deposition, and Output Simulation during Drainage Stage in Coalbed Methane Production

Diagenesis and reservoir classification criteria for Jurassic continental sandstone oil reservoir in the western Ordos Basin, China

Development Characteristics and Finite Element Simulation of Fractures in Tight Oil Sandstone Reservoirs of Yanchang Formation in Western Ordos Basin

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