Numerical Studies of Gas Production From Methane Hydrates

Abstract

Numerical Studies of Gas Production From Methane Hydrates G.J. Moridis G.J. Moridis Lawrence Berkeley National Laboratory and University of California Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Gas Technology Symposium, Calgary, Alberta, Canada, April 2002. Paper Number: SPE-75691-MS https://doi.org/10.2118/75691-MS Published: April 30 2002 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Moridis, G.J. "Numerical Studies of Gas Production From Methane Hydrates." Paper presented at the SPE Gas Technology Symposium, Calgary, Alberta, Canada, April 2002. doi: https://doi.org/10.2118/75691-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Unconventional Resources Conference / Gas Technology Symposium Search Advanced Search AbstractEOSHYDR2 is a new module for the TOUGH2 general-purpose simulator for multi-component, multiphase fluid and heat flow in the subsurface. By solving the coupled equations of mass and heat balance, EOSHYDR2 can model the non-isothermal gas release, phase behavior and flow of fluids and heat under conditions typical of common natural hydrate deposits (i.e., in the permafrost and in deep ocean sediments) in complex formations, and can describe binary hydrocarbon systems involving methane.EOSHYDR2 includes both an equilibrium and a kinetic model of hydrate formation and dissociation. The model accounts for up to four phases (gas phase, liquid phase, ice phase and hydrate phase) and up to nine components (hydrate, water, native and dissociated methane, a second native and dissociated hydrocarbon, salt, water-soluble inhibitors and heat).The mass components are partitioned among the phases, and their thermophysical properties can be described at temperatures as low as -110 °C. Dissociation, phase changes and the corresponding thermal effects are fully described, as are the effects of salt and inhibitors. The model can describe all possible hydrate dissociation mechanisms, i.e., depressurization, thermal stimulation, salting-out effects and inhibitor-induced effects.Results are presented for four test problems exploring different mechanisms and strategies for production from typical CH4-hydrate accumulations. The results of the tests tend to indicate that CH4 production from CH4-hydrate is technically feasible and has significant potential. Thermal stimulation is capable of producing substantial amounts of hydrocarbons, and its effectiveness can be enhanced when coupled with depressurization and the use of inhibitors.IntroductionGas hydrates are solid crystalline compounds in which gas molecules are encaged inside the lattices of ice crystals. These gases are referred to as guests, whereas the ice crystals are called hosts. Of particular interest are hydrates in which the gas is a hydrocarbon. Under suitable conditions of low temperature and high pressure, a hydrocarbon gas M will react with water to form hydrates according to M+ nHH2O = M·nH H2O, where nH is the hydration number.Vast amounts of hydrocarbons are trapped in hydrate deposits (Sloan, 1998). Such deposits exist where the thermodynamic conditions allow hydrate formation, and are concentrated in two distinctly different types of geologic formations where the necessary low temperatures and high pressures exist: in the permafrost and in deep ocean sediments. The lower depth limit of hydrate deposits is controlled by the geothermal gradient.Current estimates of the worldwide quantity of hydrocarbon gas hydrates range between 1015 to 1018 m3. Even the most conservative estimates of the total quantity of gas in hydrates may surpass by a factor of two the energy content of the total fuel fossil reserves recoverable by conventional methods (Sloan, 1998). The magnitude of this resource makes hydrate reservoirs a substantial future energy resource. While current economic realities do not favor gas production from hydrates, their potential clearly demands evaluation. Keywords: hydrate, dissociation, hydrate dissociation, flow assurance, upstream oil & gas, permeability, depressurization, numerical study, simulation, stimulation Subjects: Flow Assurance, Hydrates This content is only available via PDF. 2002. Society of Petroleum Engineers You can access this article if you purchase or spend a download.