A state-dependent subloading constitutive model with unified hardening function for gas hydrate-bearing sediments

Fang, Huolang; Shi, Kenan; Yu, Yong

doi:10.1016/j.ijhydene.2021.11.104

Cited by 8 publications

(2 citation statements)

References 85 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In general, elastic-plastic deformation will occur when the effective stress continuously increases and reaches the yield strength of the rock, leading to further compaction deformation and embedment. , As stated by Lei et al, the first yield onset point varies with different samples, and it is significantly determined by the mineral composition of rocks. However, it can be assumed that elastic-plastic embedment first occurs when closure pressure increases up to ε e times of rock yield stress σ y2 .…”

Section: Model Developmentmentioning

confidence: 99%

Rod-Shaped Proppant Conductivity of a Hydraulic Fracture Considering Elastic-Plastic Deformation and Embedment: An Analytical Model

Tang,

Kang,

Zhao

et al. 2024

Energy Fuels

View full text Add to dashboard Cite

Hydraulic fracturing with a proppant is widely employed to create fracture networks and enhance the conductivity of unconventional oil and gas reservoirs. However, the proppant conductivity tends to decrease due to the increasing closure pressure and temperature during long-term production. Hence, it is of great significance to quantitatively characterize the effects of thermal expansion and mechanical behaviors of proppant deformation and embedment on hydraulic fracture conductivity. In this paper, an analytical model is proposed for revealing physical relations between rod-shaped proppant conductivity and various impacting factors, and the model is validated against available experimental data. Results show that with increasing closure pressure and temperature, the rod-shaped proppant experiences pure elastic, elastic-plastic, pure plastic deformation, and linear thermal expansion, which leads to a declining proppant conductivity. Effects of critical parameters on the proppant deformation and proppant conductivity evolution are also investigated. Specifically, the proppant conductivity shows a positive relationship with the proppant aspect ratio. It is also found that with increasing closure pressure, the proppant conductivity variation can be divided into five stages. This model provides insights into the proppant deformation, embedment, and productivity, by which suggestions can be offered to optimize the parameter design in the hydraulic fracturing process, helping to realize the efficient extraction of unconventional oil and gas reservoirs.

show abstract

Section: Model Developmentmentioning

confidence: 99%

Rod-Shaped Proppant Conductivity of a Hydraulic Fracture Considering Elastic-Plastic Deformation and Embedment: An Analytical Model

Tang,

Kang,

Zhao

et al. 2024

Energy Fuels

View full text Add to dashboard Cite

show abstract

“…Based on the critical state soil mechanics, when sediments reach the critical state, all the properties of structure within the sediments would be destroyed [51]. Therefore, parameters M, Γ, and λ are constant corresponding to the host sediments regardless of hydrate saturation [68,69]. Values of ξ and S hc are related to hydrate pore habits [70].…”

Section: Development and Validation Of A Theoretical Model For Predic...mentioning

confidence: 99%

Undrained Triaxial Shear Tests on Hydrate-Bearing Fine-Grained Sediments from the Shenhu Area of South China Sea

Wei

Liu

Jia

et al. 2023

JMSE

View full text Add to dashboard Cite

Changes in undrained shear strength are important to the stability analysis of hydrate reservoirs during natural gas hydrate production. This study proposes a prediction model of undrained shear strength of hydrate-bearing fine-grained sediments based on the critical state theory. Several consolidated undrained triaxial shear tests are conducted on hydrate-bearing fine-grained samples from the Shenhu area of the South China Sea. The effects of effective consolidation stresses and hydrate saturations on the undrained shear strength are investigated. The results show that the undrained shear strength increases linearly with increasing effective consolidation stress. When the hydrate saturation is greater than the effective hydrate saturation, the undrained shear strength significantly increases with increasing hydrate saturation. The undrained shear strength of hydrate-bearing fine-grained sediments is a two-parameter function of effective hydrate saturation and a void ratio. The instability risk of the hydrate reservoir under undrained conditions is greater than that of under-drained or partially drained conditions. Furthermore, low-porosity reservoirs face more shear strength loss from hydrate decomposition yet lower risk than high-porosity ones. These results can improve the understanding of mechanical properties of hydrate-bearing fine-grained sediments under undrained conditions. This study also has implications for the design of marine structures in areas with hydrate-bearing sediment.

show abstract

A novel evaluation method of natural gas hydrate saturation in reservoirs based on the equivalent medium theory

Zhang,

Li,

Fan

et al. 2024

Geomech. Geophys. Geo-energ. Geo-resour.

View full text Add to dashboard Cite

Natural gas hydrate saturation (NGHS) in reservoirs is one of the critical parameters for evaluating natural gas hydrate resource reserves. Current widely-accepted evaluation methods developed for evaluating conventional natural gas saturation in reservoirs, to some extents, are not sufficient enough to obtain accurate predicted results. In light of the equivalent medium theory, the natural gas hydrate is regarded as the fluid (Mode A) when NGHS is relatively low, while it is regarded as the rock matrix (Mode B) when NGHS is high. Two mathematical model are then developed for evaluating NGHS at Mode A and B. Experimental verification shows that R2 of the predicted results based upon the proposed model is 0.968, and the average absolute relative error percentage is 8.90%. The error of the predicted results gradually decreases with increasing NGHS, whereas increases with increasing confining pressure. In addition, the proposed model has been applied to the 142.9–147.7 m well section of Well DK-1 in the permafrost region, Qilian Mountains. The results show that the error of the predicted results is less than 13.92%, with its average error being 10.51%. The predicted value gradually increases with its error decreasing as the depth continues to increase, which is consistent with the change behavior of measured data. NGHS evaluation method proposed in this paper fully considers the occurrence form of natural gas hydrate in reservoirs. The model parameters are easy to determine and the predicted results are reliable.

show abstract

A state-dependent subloading constitutive model with unified hardening function for gas hydrate-bearing sediments

Cited by 8 publications

References 85 publications

Rod-Shaped Proppant Conductivity of a Hydraulic Fracture Considering Elastic-Plastic Deformation and Embedment: An Analytical Model

Rod-Shaped Proppant Conductivity of a Hydraulic Fracture Considering Elastic-Plastic Deformation and Embedment: An Analytical Model

Undrained Triaxial Shear Tests on Hydrate-Bearing Fine-Grained Sediments from the Shenhu Area of South China Sea

A novel evaluation method of natural gas hydrate saturation in reservoirs based on the equivalent medium theory

Contact Info

Product

Resources

About