Multiple porosity model of a heterogeneous layered gas hydrate deposit in Ulleung Basin, East Sea, Korea: A study on depressurization strategies, reservoir geomechanical response, and wellbore stability

Yoon, Heesung; Yoon, Sangcheol; Lee, Jooyong; Kim, Jihoon

doi:10.1016/j.jngse.2021.104321

Cited by 21 publications

(33 citation statements)

References 29 publications

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“…The fixed-stress method is modified for the MP model as in the previous study [3,17] to solve coupled flow and geomechanics [28]. Equation (23) with the Lagrange porosity function and its correction is then linearized as…”

Section: Fixed-stress Sequential Methodsmentioning

confidence: 99%

“…We consider an MP material and its constitutive relations by restating those in [3,17]. In the coupled system of heat-flow and geomechanics, total stress σ and fluid mass m l,J are in relations having functions of the fluid pressure p l,J , temperature T l , and total strain ε.…”

Section: Multiple Porosity (Mp) Materials and Constitutive Relationsmentioning

confidence: 99%

“…Several methods to dissociate and produce gas from the hydrates were proposed in the literature and experiments including the depressurization and thermal stimulation [1,2]. Recently, various depressurization strategies have been investigated aiming at the improved geomechanical/wellbore stability while maintaining the productivity [3]. Because the hydrates are buried mostly in the unconsolidated sands distributed in the deep sea or permafrost regions over the globe, precise monitoring schemes for the gas hydrate deposits in terms of both the fluid flow and the geomechanical responses accompanied during the dissociation process cannot be stressed enough to enhance the productivity and safety.…”

Section: Introductionmentioning

confidence: 99%

“…The objective of this study is to investigate the feasibility of the EM method focusing on the detectability of the fluid flow, i.e., the flow of dissociated methane from the gas hydrate. To this end, we apply an integrated flow-geomechanics-EM geophysics simulation to a specific gas hydrate deposit, located near the site of UBGH2-6 in the Ulleung Basin, East Sea, Korea [3,15,16]. For coupled flow-geomechanical simulation first, depressurization induces the dissociation of hydrates, which results in the flow of fluids (gas and water) in the quasi-static state assumed.…”

Section: Introductionmentioning

confidence: 99%

“…For coupled flow-geomechanical simulation first, depressurization induces the dissociation of hydrates, which results in the flow of fluids (gas and water) in the quasi-static state assumed. The multiple porosity (MP) model [3,17] is employed to reduce the high computational costs for the field-wide simulation, especially for the geomechanics calculation of a vertically heterogeneous deposit with a very thin and intercalated reservoir compared to the overburden. Several simulators exist for coupled flow and geomechanics simulation, especially for the gas hydrates which are either based on the kinetic and equilibrium model, such as MH21 [18], STOMP-HYD-KE [19], or TOUGH+HYDRATE [20].…”

Section: Introductionmentioning

confidence: 99%

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Integration of Electromagnetic Geophysics Forward Simulation in Coupled Flow and Geomechanics for Monitoring a Gas Hydrate Deposit Located in the Ulleung Basin, East Sea, Korea

Yoon

Kim

et al. 2022

Energies

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We investigate the feasibility of electromagnetic (EM) geophysics methods to detect the dissociation of gas hydrate specifically from a gas hydrate deposit located in the Ulleung Basin, East Sea, Korea via an integrated flow-geomechanics-EM geophysics simulation. To this end, coupled flow and geomechanics simulation is first performed with the multiple porosity model employed, where a mixed formulation with the finite volume (FV) and finite element (FE) methods are taken for the flow and geomechanics, respectively. From the saturation and porosity fields obtained from the coupled flow and geomechanics, the electrical conductivity model is established for the EM simulation. Solving the partial differential equation of electrical diffusion which is linearized using the 3D finite element method (FEM), the EM fields are then computed. For numerical experiments, particularly two approaches in the configuration for the EM methods are compared in this contribution: the surface-to-surface and the surface-to-borehole methods. When the surface-to-surface EM method is employed, the EM is found to be less sensitive, implying low detectability. Especially for the short term of production, the low detectability is attributed to the similarity of electrical resistivity between the dissociated gas (CH4) and hydrate as well as the specific dissociation pattern within the intercalated composites of the field. On the other hand, when the surface-to-borehole EM method is employed, its sensitivity to capture the produced gas flow is improved, confirming its detectability in monitoring gas flow. Hence, the EM geophysics simulation integrated with coupled flow and geomechanics can be a potential tool for monitoring gas hydrate deposits.

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Section: Fixed-stress Sequential Methodsmentioning

confidence: 99%

Section: Multiple Porosity (Mp) Materials and Constitutive Relationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Integration of Electromagnetic Geophysics Forward Simulation in Coupled Flow and Geomechanics for Monitoring a Gas Hydrate Deposit Located in the Ulleung Basin, East Sea, Korea

Yoon

Kim

et al. 2022

Energies

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Sequential formulation of all‐way coupled finite strain thermoporomechanics for largely deformable gas hydrate deposits

Kim,

Lee

2024

Num Anal Meth Geomechanics

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We develop a numerically stable sequential formulation of thermoporomechanics for largely deformable gas hydrate deposits, extended from the fixed stress split of infinitesimal transformation. Constitutive equations are based on the total Lagrangian approach for both flow and geomechanics, including dynamic full tensor permeability and thermal conductivity updated from the deformation gradient. For space discretization, we take the cell‐centered finite volume and node‐based finite element method for flow and geomechanics, respectively. Then, we propose a sequential implicit method for all‐way coupled thermoporomechanics, where the nonisothermal multiphase flow problem of gas hydrates is solved implicitly first and then the geomechanics problem is solved implicitly at the next step. During solution of the flow problem, we fix the rate of first Pioal total stress for numerical stability as well as apply porosity correction and entropy correction to account for geomechanical effects. We test numerical examples where flow and geomechanics parameters are based on deep oceanic gas hydrate deposits. When applying depressurization, even though the results between the infinitesimal transformation and finite strain geomechanics are similar in the early stages due to small deformation, we find differences between them in the late times as deformation becomes large. Accordingly, permeability and thermal conductivity tensors become nonisotropic full tensors although they are initially isotropic. We identify numerical stability of the developed sequential method from the test cases that exhibit the highly complex coupled gas hydrate systems with large deformation. Thus, the proposed sequential formulation can be applied in largely deformable gas hydrate systems.

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Long-term numerical simulation of a joint production of gas hydrate and underlying shallow gas through dual horizontal wells in the South China Sea

et al. 2022

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Multiple porosity model of a heterogeneous layered gas hydrate deposit in Ulleung Basin, East Sea, Korea: A study on depressurization strategies, reservoir geomechanical response, and wellbore stability

Cited by 21 publications

References 29 publications

Integration of Electromagnetic Geophysics Forward Simulation in Coupled Flow and Geomechanics for Monitoring a Gas Hydrate Deposit Located in the Ulleung Basin, East Sea, Korea

Integration of Electromagnetic Geophysics Forward Simulation in Coupled Flow and Geomechanics for Monitoring a Gas Hydrate Deposit Located in the Ulleung Basin, East Sea, Korea

Sequential formulation of all‐way coupled finite strain thermoporomechanics for largely deformable gas hydrate deposits

Long-term numerical simulation of a joint production of gas hydrate and underlying shallow gas through dual horizontal wells in the South China Sea

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