Anisotropic Damage to Hard Brittle Shale with Stress and Hydration Coupling

Gui, Junchuan; Ma, Tianshou; Chen, Ping; Yuan, Heyi; Guo, Zhaoxue

doi:10.3390/en11040926

Cited by 27 publications

(18 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ma et al [21] proposed a novel theoretical method to underpin the failure mechanisms of anisotropic rocks under Brazilian test conditions. Gui et al [22,23] reported on anisotropic damage of shale stress coupled with hydration and proposed the conclusion that damage parameters parallel to bedding are greater than those perpendicular to bedding. Wan et al [24] analyzed the anisotropy of the diffusivity of gas shale, and the diffusivity is much higher at the parallel to the bedding direction than that at perpendicular direction.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Difference of Shale Mechanical Properties

Liu

Sun

et al. 2021

Advances in Civil Engineering

View full text Add to dashboard Cite

This paper studies the anisotropic characteristics of shale and the difference in mechanical performance between deep shale and outcrop shale. The outcrop shale was collected from the Shuanghe section in Changning County, southern Sichuan, and the deep shale was collected from the Wells Yi201 and Lu202. Study their basic mechanical parameters, failure modes, and wave velocity responses through laboratory tests. Research shows that with the increase of bedding angle, the deformation mode has the trend from elastic deformation to plastic deformation in high-stress state. When the bedding angles are 0°, 30°, and 45°, the weak bedding surface plays a leading role in the formation of the failure surface trend. As the bedding angle increases to 60° and 90°, its influence is weakened. The tensile strength, elastic modulus, and wave velocity decrease with the increase of bedding angle. The compressive strength and Poisson’s ratio have the law of U-type change, there are higher values at 0° and 90°, and the lowest values are at 30°. The brittleness index first increases and then decreases with the increase of the bedding angle. The tensile strength and Poisson’s ratio of outcrop shale and deep shale are close, but the compressive strength of deep shale is only 1/3 of outcrop shale, the elastic modulus is only 3/4 of outcrop shale, and the failure of deep shale is accompanied by instability failure.

show abstract

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Difference of Shale Mechanical Properties

Liu

Sun

et al. 2021

Advances in Civil Engineering

View full text Add to dashboard Cite

show abstract

“…As for the hydration damage of shale oil reservoir and its influence on permeability, the following contents need to be supplemented. First of all, the existing research object of hydration damage is usually the outcrop core of marine strata [23,24]. Because of the difference of geological environment and lithologic composition, the research results cannot reflect the hydration damage law of continental oil shale reservoir.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Hydration Damage and Its Influence on Permeability of Lamellar Shale Oil Reservoirs in Ordos Basin

et al. 2021

View full text Add to dashboard Cite

The continental shale oil reservoir has low permeability, high clay content, rich lamellar structure, and strong heterogeneity, which makes the reservoir vulnerable to hydration damage. In order to study characteristics of hydration damage and its influence on permeability of lamellar shale oil reservoirs, a series of experiments such as high-pressure mercury injection, steady gas permeability, rock thin section identification, and scanning electron microscope were carried out with the downhole core in Ordos Basin as the experimental object. The effects of water and water-based drilling fluid on pore size distribution, permeability, and rock microstructure were analyzed. Results show that the pore size of the reservoir is mainly nanoscale, and the pore size of shale changes most dramatically in the stage of hydration for 12-24 hours, while that of tuff changes most dramatically in 24-48 hours. The permeability increases rapidly with hydration time and then tends to be stable, among which the permeability of samples with lamellar structure in the direction parallel to the lamellar structure is most easily affected by hydration and changes fastest. Hydration leads to the formation of new pores, new fractures, and the expansion of existing fractures in rocks, especially in the strata containing large amounts of terrigenous clastic, lamellar structure, and pyrite. The new seepage channel increases the permeability of rock, and the soil powder and plugging particles in drilling fluid are easy to form protective mud cake in these places. These protective mud cakes not only change the microstructure of rock but also inhibit the influence of hydration on the pore space and permeability of rock, which play an effective role in preventing the mineral shedding on the rock surface, reducing the increase of micropores and delaying hydration.

show abstract

“…Drilling fluid enters the wellbore through the action of hydraulic pressure difference and permeability potential difference. The rock around the wellbore is prone to hydration when it encounters water; hydration can reduce the rock strength and cause instability of the wellbore [6,22,23].…”

Section: The Circumferential Stress Generated By Ground Stress On Thementioning

confidence: 99%

Calculation Model of Rock Fracture Pressure with Multifields in the Process of Fracturing

Zhao

et al. 2018

Mathematical Problems in Engineering

View full text Add to dashboard Cite

In this paper, a comprehensive model to calculate the rock fracture pressure by the theory of double effective stress of porous medium is established, which considers such effective factors as the crustal stress field, hydration stress field, temperature field, tectonic stress field, the porosity of rock, and additional stress field generated by seepage of drilling fluid. This new model is applicable to predict the fracture pressure of different types of rocks. Using the experimental parameters of field fracturing and the experimental results of three-axis compression of rock cores with different water contents, we may get the calculated fracture pressure. Compared with the measured fracture pressure in the oilfield, the result calculated in the present study shows good agreement. Besides, the effects of water contents on the tensile strength and fracture pressure are analyzed. Results show that both the tensile strength and fracture pressure decrease with the increase of water contents, which is due to the reduction of the mechanical properties of rocks by hydration.

show abstract

Anisotropic Damage to Hard Brittle Shale with Stress and Hydration Coupling

Cited by 27 publications

References 37 publications

Experimental Study on the Difference of Shale Mechanical Properties

Experimental Study on the Difference of Shale Mechanical Properties

Characteristics of Hydration Damage and Its Influence on Permeability of Lamellar Shale Oil Reservoirs in Ordos Basin

Calculation Model of Rock Fracture Pressure with Multifields in the Process of Fracturing

Contact Info

Product

Resources

About