The developmental characteristics of natural fractures and their significance for reservoirs in the Cambrian Niutitang marine shale of the Sangzhi block, southern China

Wang, Xinghua; Ding, Wenlong; Cui, Long; Wang, Ruyue; He, Jianhua; Li, Ang; Gu, Yang; Liu, Jingshou; Xiao, Zikang; Fu, Fuquan

doi:10.1016/j.petrol.2018.02.042

Cited by 46 publications

(17 citation statements)

References 15 publications

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“…In addition, shale gas preservation is affected by burial depth, roof and floor conditions, structural morphology, pressure coefficient, fracture characteristics and distribution, fault, and material basis. Among them, natural fracture plays an important role in the preservation and gas-bearing property of shale gas, which is an important geological factor for evaluating and optimizing the favorable target areas for shale gas exploration and development. − As for the formation stages of shale reservoir fractures, macrogeological analysis and microexperimental methods are mainly used at present. Macrogeological analysis mainly includes structural evolution analysis, matching relationship of multiscale fracture occurrence, and multiscale fracture intersection relationship.…”

Section: Introductionmentioning

confidence: 99%

Formation Stages and Evolution Patterns of Structural Fractures in Marine Shale: Case Study of the Lower Silurian Longmaxi Formation in the Changning Area of the Southern Sichuan Basin, China

Fan

Zhao

et al. 2020

Energy Fuels

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Taking the Lower Silurian Longmaxi Formation in the Changning area of the southern Sichuan Basin as an example, the characteristics and formation stages of tectonic fractures are comprehensively studied by regional scale geological analysis and microscopic scale experimental tests. Regional scale geological analysis shows that there are mainly high-angle and vertical structural fractures, which have the characteristics of small opening, large spacing, small fracture density, and high filling degree. The fracture systems can be divided into three stages and six groups, which correspond to the structural compression in the near south−north, northwest, and northeast directions. The microscopic scale experimental test analysis confirmed that the formation of tectonic fractures mainly experienced three stages of tectonic movements, namely, the Middle−Late Yanshanian tectonic movement (136− 94 million years ago (Ma)), the Late Yanshanian tectonic movement−Early Himalayan tectonic movement (94−67 Ma), and the Middle−Late Himalayan tectonic movement (67−0 Ma). The corresponding uniform temperatures of the fracture filling inclusions are 118.5−140.2, 91.6−108.5, and 73.2−82.2 °C, respectively. Based on the tectonic analysis and geomechanical principles, an evolutionary model of structural fractures was established. Fractures with early formation and high filling degree and fractures with late formation but large angle between the fracture orientation and current geostress direction are beneficial to shale gas enrichment.

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Section: Introductionmentioning

confidence: 99%

Formation Stages and Evolution Patterns of Structural Fractures in Marine Shale: Case Study of the Lower Silurian Longmaxi Formation in the Changning Area of the Southern Sichuan Basin, China

Fan

Zhao

et al. 2020

Energy Fuels

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“…e physical characteristics of shale reservoirs are highly related to the mineral fraction, mineral content, the level of natural crack development, etc. When shale reservoirs have a high content of brittle minerals, showing a significantly great modulus of elasticity and a low Poisson's ratio [17,31,46]. To further understand the effect of reservoir properties on shale permeability damage rate and stress sensitivity, an INSTRON 1346 electrohydraulic servo-controlled material testing machine (200T) was used to perform uniaxial compression tests on five shale samples with axial loading and selected displacement control, the test axial displacement loading rate was 0.01 mm/min, and the loading equipment and schematic diagram are shown in Figure 3.…”

Section: Uniaxial Compression Testmentioning

confidence: 99%

“…e study of shale maturation and formation evolution is based on the reservoir physical and petrographic characteristics of the shale, with diagenesis and tectonics playing a significant role in the formation and evolution of the shale [6][7][8][9]. e pore is the site of shale gas adsorption and storage [10][11][12][13][14], while natural fractures are the transport channels for shale oil and gas, both of which are inextricably linked to tectonic stress, mineral property, and mineral content [15][16][17][18][19]. Scholars have studied the characteristics of shale pore, formation and evolution mechanisms, and the distribution of brittle minerals under complex tectonics, and concluded that there is a correlation between shale pore and mineral property and distribution under complex tectonics [20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Study of the Effect of Mineral Components on the Permeability Impairment Rate and Stress Sensitivity Factor of Shale

Wang

Chen

et al. 2022

Geofluids

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The mineral components play an indispensable role in shale reservoirs, and the study of their content and character are significant for the permeability impairment rate and stress sensitivity of shale reservoirs. In this study, the shale cores from the FC1 well of the Lower Cambrian Niutitang Formation in northern Guizhou were used to analyze the mineralogical composition of five samples using X-ray diffractometry and for measurement of permeability and porosity of samples by means of the FYKS-2 high-temperature overburden porosimeter with N2, and the samples were also subjected to uniaxial compression tests using the INSTRON 1346 electrohydraulic servo-controlled material testing machine (200T), thereby analyzing the effect of mineral components on the permeability impairment rate and stress sensitivity coefficient of shale. Results indicate that the permeability and porosity are negatively correlated with effective stress and clay mineral content, and positively correlated with detrital mineral content, whereas, the change of mineral composition is not obvious for porosity. Simultaneously, the permeability impairment rate and stress sensitivity factor decrease with growing quartz content and modulus of elasticity, and increase with rising clay mineral content. Additionally, the greater the brittle minerals content of shale, the more likely it is to undergo brittle damage and more crack extension during compression with predominantly elastic deformation, resulting in a lower stress sensitivity factor. Conversely, the higher is the stress sensitivity factor. The research results further deepen the understanding of mineral components on the permeability and mechanical properties of shale reservoirs.

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“…These natural fractures are effective storage spaces and main seepage channels for shale oil reservoirs [7][8][9][10][11]. Natural fractures not only control the migration, accumulation, preservation, and single well productivity of shale oil, but also affect the fracturing measures and production results [12][13][14][15][16][17]. Therefore, the quantitative prediction of fracture distribution has an important guiding significance for shale oil exploration and development.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Prediction of Natural Fractures in Shale Oil Reservoirs

et al. 2021

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Natural fractures are the key factors controlling the enrichment of shale oil. It is of great significance to clarify the distribution of natural fractures to guide the selection of sweet spots for shale oil. Taking the Qing-1 Member shale oil reservoir in the northern Songliao Basin, China as an example, a new method considering the factors affecting fracture distribution was proposed to quantitatively predict the structural fractures. And the effect of natural fractures on shale oil enrichment was discussed. Firstly, the types and characteristics of fractures in shale oil reservoirs are characterized by using core and outcrop data. Combined with the experimental analysis, the influences of fault, mechanical stratigraphy, mineral composition and content, TOC, and overpressure on fracture intensity were clarified. Then, the number and density of fractures are quantitatively predicted according to the power-law distribution of fault length. Next, geomechanical simulation and fracture prediction were carried out on the model which was established with comprehensive consideration of the influencing factors of fracture distribution. Finally, the fracture distribution is evaluated comprehensively based on above prediction. The prediction results in this work are consistent with the core measurements.

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The developmental characteristics of natural fractures and their significance for reservoirs in the Cambrian Niutitang marine shale of the Sangzhi block, southern China

Cited by 46 publications

References 15 publications

Formation Stages and Evolution Patterns of Structural Fractures in Marine Shale: Case Study of the Lower Silurian Longmaxi Formation in the Changning Area of the Southern Sichuan Basin, China

Formation Stages and Evolution Patterns of Structural Fractures in Marine Shale: Case Study of the Lower Silurian Longmaxi Formation in the Changning Area of the Southern Sichuan Basin, China

Study of the Effect of Mineral Components on the Permeability Impairment Rate and Stress Sensitivity Factor of Shale

Quantitative Prediction of Natural Fractures in Shale Oil Reservoirs

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