Effect of fluid–solid coupling on shale mechanics and seepage laws

Song, Fuquan; Hu, Xiao; Ji, Kai; Huang, Xuewei

doi:10.1016/j.ngib.2017.12.001

Cited by 16 publications

(4 citation statements)

References 3 publications

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“…During the drilling process, the working fluid filtrate easily invaded the formation along the lithologic interface microfractures under the action of the bottom-hole pressure difference and capillary force. Meanwhile, micro-fractures may induce a pressure penetration effect, which will aggravate the rock fragmentation and reduce the rock mechanical strength of formation, resulting in borehole instability. , …”

Section: Resultsmentioning

confidence: 99%

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Study on the Mechanical Properties and Failure Law of Rocks with Interbedded Sand and Mud

et al. 2022

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In view of the borehole instability during the drilling process of the thin sand and mud interbedded sections in the Shahejie Formation, the physicochemical and mechanical properties of sand and mud interbed rock were studied through a series of laboratory tests to determine the main factors influencing the formation instability. The effects of fracture development of interbed sand and mud, mechanical weak plane, borehole trajectory, and seepage effect on borehole stability were evaluated and analyzed through the established model. The results indicated that the microcracks are developed on the lithologic interface due to the change of lithology of the sand–mud interbed. The anisotropy of the mechanical properties of the rocks with interbedded sand and mud is obvious, which leads to the great mechanical weak plane effect on the wellbore stability. The bottom-hole pressure difference leads to the seepage effect, which reduces the effective supporting force of the drilling fluid on the borehole wall and promotes rock sliding and failure along the lithologic interface developed by the sand–mud thin interbedded layer. Considering the influence of the borehole trajectory, mechanical weak plane, and seepage effect, the recommended drilling fluid density in the deviated section is 1.69 g/cm3. The wellbore stability is the best when drilling along the direction of the minimum horizontal principal stress in the horizontal section. Further strengthening the plugging performance of the drilling fluid, drilling through the microfractures vertically on the interbedded lithologic interface, and reducing the lateral vibration of the drilling tools as far as possible are necessary. The research results provide a theoretical basis for the safe drilling of thin sand and mud interbedded strata.

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Section: Resultsmentioning

confidence: 99%

“…Meanwhile, micro-fractures may induce a pressure penetration effect, which will aggravate the rock fragmentation and reduce the rock mechanical strength of formation, resulting in borehole instability. 24,25 3.2. Mechanical Experimental Testing of Underground Cores.…”

Section: Physical and Chemical Experimentalmentioning

confidence: 99%

Study on the Mechanical Properties and Failure Law of Rocks with Interbedded Sand and Mud

et al. 2022

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“…Hydration can promote the expansion of original fractures, and also induce new microfractures or branches [33], and the direction of bedding is the main factor controlling the direction of fracture propagation [34]. Hydration is conducive to fracturing shale gas reservoirs, to achieve the goal of increasing production [35].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Lamina Density and Occurrence on the Permeability of Lamellar Shale after Hydration

et al. 2021

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The characteristics of laminae in lamellar shale oil reservoirs have important influences on reservoir parameters, especially permeability. In order to explore the influence of lamina density and occurrence on the permeability of lamellar shale after hydration, we studied the lamellar shale in the Chang 7 member of the Yanchang Formation of Triassic in Ordos Basin. By comparing the permeability of bedding shale and lamellar shale with different densities of laminae, it was found that the permeability anisotropy of lamellar shale was stronger. In the direction parallel to the lamina, the permeability increased approximately linearly with an increase in lamina density. The effect of hydration on rock micropore structure and permeability was studied by soaking shale in different fluids. Most of the microfracture in the lamellar shale was parallel to the lamina direction, and hydration led to a widening of the microfracture, which led to the most obvious increase in permeability parallel to the lamina. Collectively, the research results proved that lamina density, occurrence, and hydration have a significant influence on the permeability anisotropy of lamellar shale.

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“…Song et al studied the influence of fluid-solid coupling on shale mechanics and seepage laws. e shale seepage tests under different saturations show that, under fluid-solid coupling conditions, the higher the saturation, the higher the propagation and the seepage ability of microcracks under pressure [17]. Huang et al carried out numerical analysis on the hydrothermal coupling model of lowtemperature fractured rocks.…”

Section: Introductionmentioning

confidence: 99%

Effect of Colluvial Soil Slope Fracture’s Anisotropy Characteristics on Rainwater Infiltration Process

Zeng

Liu

Zhang

et al. 2018

Advances in Civil Engineering

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The SEEP/W module of finite element software GEO-slope is used to analyze the effects of fracture depth, permeability coefficient ratio, fracture angle, and fracture number on the rainwater infiltration process. Moreover, the effect of fracture seepage anisotropy on slope stability is discussed combining with unsaturated seepage theory. The results show that the pore water pressure in the fracture increases rapidly with the rainfall until it changes from negative pressure to positive pressure. The greater the fracture depth is, the greater the pore water pressure in the fracture is, and the greater the infiltration depth at the time of rainfall stopping is. When the permeability coefficient is greater than the rainfall intensity, the permeability coefficient ratio has a great influence on the infiltration process of rainwater. The smaller the fracture angle is, the greater the maximum pore water pressure is in the fracture depth range, and the greater the depth of the positive pore water pressure is. However, with the increase of fracture angle, the infiltration depth decreases, and the range of the surface saturation area of slope increases obviously. With the increase of fracture density, the saturated positive pressure region is connected to each other in the slope. The influence range and the degree of the rainwater on the seepage field are larger and larger. There is a power relation between the saturation area and the fracture number, and also the concentration distribution of long fractures directly forms the large-connected saturated zone and raises groundwater. The range of the saturated zone and variation law of the pore water pressure under fracture seepage are obtained, which provide a reference for the parameter partition assignment of slope stability analysis under fracture seepage.

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Effect of fluid–solid coupling on shale mechanics and seepage laws

Cited by 16 publications

References 3 publications

Study on the Mechanical Properties and Failure Law of Rocks with Interbedded Sand and Mud

Study on the Mechanical Properties and Failure Law of Rocks with Interbedded Sand and Mud

The Influence of Lamina Density and Occurrence on the Permeability of Lamellar Shale after Hydration

Effect of Colluvial Soil Slope Fracture’s Anisotropy Characteristics on Rainwater Infiltration Process

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