Toward Production From Gas Hydrates: Current Status, Assessment of Resources, and Simulation-Based Evaluation of Technology and Potential

Abstract

Summary Gas hydrates (GHs) are a vast energy resource with global distribution in the permafrost and in the oceans. Even if conservative estimates are considered and only a small fraction is recoverable, the sheer size of the resource is so large that it demands evaluation as a potential energy source. In this review paper, we discuss the distribution of natural GH accumulations, the status of the primary international research and development (R&D) programs, and the remaining science and technological challenges facing the commercialization of production. After a brief examination of GH accumulations that are well characterized and appear to be models for future development and gas production, we analyze the role of numerical simulation in the assessment of the hydrate-production potential, identify the data needs for reliable predictions, evaluate the status of knowledge with regard to these needs, discuss knowledge gaps and their impact, and reach the conclusion that the numerical-simulation capabilities are quite advanced and that the related gaps either are not significant or are being addressed. We review the current body of literature relevant to potential productivity from different types of GH deposits and determine that there are consistent indications of a large production potential at high rates across long periods from a wide variety of hydrate deposits. Finally, we identify (a) features, conditions, geology and techniques that are desirable in potential production targets; (b) methods to maximize production; and (c) some of the conditions and characteristics that render certain GH deposits undesirable for production.

Storage of Methane in Clathrate Hydrates: Monte Carlo Simulations of sI Hydrates and Comparison with Experimental Measurements

“…The water molecules can form, through hydrogen-bonding, different types of cages/cavities that can be stabilized by the presence of guest molecules of particular sizes that can fit within the cages. Commonly encountered types of cages in hydrate-related studies include the following: pentagonal dodecahedron (5 12 ), tetrakaidecahedron (5 12 6 2 ), hexakaidecahedron (5 12 6 4 ), irregular dodecahedron (4 3 5 6 6 3 ), and icosahedron (5 12 6 8 ). Different combinations of cage-types and cage-numbers can produce the building blocks (unit cells) for the three most common (i.e., sI, sII, and sH) hydrate structures.…”

“…As a result of the discovery of large amounts of methane (CH 4 ) hydrates during the recent years in natural, geologic environments (e.g., inside oceanic sediments at the continental slopes, and at the Arctic permafrost regions), hydrates are currently considered possible future energy sources. − Preliminary estimates − of the total amount of CH 4 gas that is stored in hydrate deposits are encouraging and thus make the study of CH 4 hydrates very attractive, even though the total amount of stored CH 4 gas is still under debate within the scientific community.…”

Diffusion Model for Gas Replacement in an Isostructural CH4–CO2 Hydrate System

“…Such settings represent fluid flow between injectors and producers in a class-I GH reservoir. 44,45 The input parameters used in our long-term E1, Supporting Information). In all tests, the thickness of the initially reformed layer is assumed to be Δ 0 ≈ 10 μm, while three different SSA-equivalent radii r 0 = 69, 242, and 830 μm (i.e., mean respective particle radii ⟨r 0 ⟩ = 50, 175, and 600 μm at standard deviation γ 0 = 0.42) are explored.…”

“…For simplicity, we also assume that there is no free pore water that would instantly convert to CO 2 hydrate in contact with the injected fluid, with probably detrimental consequences for the reservoir permeability. Such settings represent fluid flow between injectors and producers in a class-I GH reservoir. , The input parameters used in our long-term simulations are presented in Table , based on results given in Appendix D (see Table D1, Supporting Information); diffusion coefficients are Arrhenius extrapolations of the constants inferred in run 2 (6 MPa, 277 K) with the activation energies deduced in Appendix E (see Figures E1 and E2, Table E1, Supporting Information). In all tests, the thickness of the initially reformed layer is assumed to be Δ 0 ≈ 10 μm, while three different SSA-equivalent radii r 0 = 69, 242, and 830 μm (i.e., mean respective particle radii ⟨ r 0 ⟩ = 50, 175, and 600 μm at standard deviation γ 0 = 0.42) are explored.…”

Study on Hydrate Production Behaviors by Depressurization Combined with Brine Injection in the Excess-Water Hydrate Reservoir

“…Due to the increasing demand for energy and the increasing problem of environmental pollution, the development of new clean energy is the demand of the times. Natural gas hydrate widely exists in permafrost and seabed [ 1 , 2 ], and is considered to be an important energy source for the future because of its large reserves and low environmental pollution [ 3 , 4 ]. To study the feasibility of producing gas hydrate, the United States, Canada, Japan, and China have performed several trial productions, which have proven the feasibility of producing natural gas hydrate by thermal stimulation, depressurization, and carbon dioxide replacement [ 5 , 6 , 7 , 8 , 9 ].…”