Geomechanical behaviors of shale after water absorption considering the combined effect of anisotropy and hydration

Zhang, Qiangui; Fan, Xiangyu; Chen, Ping; Ma, Tianshou; Zeng, Feitao

doi:10.1016/j.enggeo.2020.105547

Cited by 66 publications

(34 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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

Self Cite

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

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…The behavior of clay rocks subjected to desiccation and hydration processes has been studied in the literature. [34][35][36][37][38] In some clay-rich shales, these processes have been observed to induce changes in the degree of mechanical anisotropy. 39,40 Mechanical anisotropy has been shown to be saturation-dependent in these rocks, with the anisotropy ratio generally increasing as the shale dehydrates.…”

Section: Introductionmentioning

confidence: 99%

“…38,[41][42][43] The Young's modulus and compressive strength were found to be more sensitive to the degree of saturation (DOS) in the BP direction. 38,42,44,45 The fracture pattern and failure mode observed in triaxial tests have also been noted to depend on the DOS for certain bedding-plane orientations. 43 As a result, saturation-dependent mechanical anisotropy may affect the swelling and shrinkage behavior of rocks.…”

Section: Introductionmentioning

confidence: 99%

Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks

Borja

2021

Num Anal Meth Geomechanics

View full text Add to dashboard Cite

Many clay rocks have distinct bedding planes. Experimental studies have shown that their mechanical properties evolve with the degree of saturation (DOS), often with higher stiffness and strength after drying. For transversely isotropic rocks, the effects of saturation can differ between the bed-normal (BN) and bedparallel (BP) directions, which gives rise to saturation-dependent stiffness and strength anisotropy. Accurate prediction of the mechanical behavior of clay rocks under partially saturated conditions requires numerical models that can capture the evolving elastic and plastic anisotropy with DOS. In this study, we present an anisotropy framework for coupled solid deformation-fluid flow in unsaturated elastoplastic media. We incorporate saturation-dependent strength anisotropy into an anisotropic modified Cam-Clay (MCC) model and consider the evolving anisotropy in both the elastic and plastic responses. The model was calibrated using experimental data from triaxial tests to demonstrate its capability in capturing strength anisotropy at various levels of saturation. Through numerical simulations, we demonstrate the role of evolving stiffness and strength anisotropy in the mechanical behavior of clay rocks. Plane strain simulations of triaxial compression tests were also conducted to demonstrate the impacts of material anisotropy and DOS on the mechanical and fluid flow responses.

show abstract

“…27,28 In some fields, water invasion is inevitable when bentonite is in service. [29][30][31][32][33][34] The bentonite hydration initially occurs at the crystalline level, 35 and osmotic hydration follows till the disintegration of the whole structure. 36 The hydration of bentonite leads to a series of issues.…”

Section: Introductionmentioning

confidence: 99%

“…29,30 During drilling in rich montmorillonite formation, the wellbore may collapse when water-base drilling fluid is used. 31,32 In the coating industry, durability and stability face challenges. 33,34 To solve the above problems, inorganic/organic salts, [37][38][39] nanoparticles, 40,41 surfactants, 42,43 polymers 44,45 have been developed to inhibit the hydration of bentonite.…”

Section: Introductionmentioning

confidence: 99%

Properties and mechanism of a poly(ionic liquid) inhibitor contained bi‐functional groups for bentonite hydration

Wang

Gao

Jia

et al. 2021

J of Applied Polymer Sci

View full text Add to dashboard Cite

Present polymer inhibitors depend on a major inhibitory group to restrain bentonite hydration, and monomer design is concerned to improve the inhibition and stability through complex copolymerization. Conveniently, a homopolymer (PIL-NH 2 ) that contained primary amine and cationic imidazolium as bi-functional groups was proposed, aiming to provide two synergistic inhibitory modes. Comprehensive methods were conducted to characterize the chemical structure and inhibitory performance of PIL-NH 2 . The ζ potential absolute value of bentonite suspension was decreased by PIL-NH 2 from 28.7-33.3 mV to 4-7 mV, and the increment of bentonite particle size d 50 was observable from 1.83892 μm to over 200 μm. With water squeezed out, the lattice spacing d 001 of hydrated bentonite was reduced from 1.9070 to 1.2683 nm due to PIL-NH 2 intercalation. The ESEM images revealed that inhibited bentonite showed a tight structure with classical dehydration phenomenon, and the hydrogen bond between PIL-NH 2 and bentonite was further confirmed according to the FT-IR result. In mechanism analysis, the electrostatic attraction and hydrogen bond existed simultaneously for PIL-NH 2 to adsorb bentonite. The two adsorption modes from bi-functional groups were synergistic to improve inhibition remarkably. PIL-NH 2 maintained high performance during the whole hydration process, including crystalline hydration, osmotic hydration, and hydrated dispersion.

show abstract

Geomechanical behaviors of shale after water absorption considering the combined effect of anisotropy and hydration

Cited by 66 publications

References 51 publications

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

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

Evolution of anisotropy with saturation and its implications for the elastoplastic responses of clay rocks

Properties and mechanism of a poly(ionic liquid) inhibitor contained bi‐functional groups for bentonite hydration

Contact Info

Product

Resources

About