Numerical Simulation Studies of Thermally-Induced Gas Production From Hydrate Accumulations With No Free Gas Zones at the Mallik Site, Mackenzie Delta, Canada
Bibliographic record
Abstract
Numerical Simulation Studies of Thermally-Induced Gas Production From Hydrate Accumulations With No Free Gas Zones at the Mallik Site, Mackenzie Delta, Canada 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 Asia Pacific Oil and Gas Conference and Exhibition, Melbourne, Australia, October 2002. Paper Number: SPE-77861-MS https://doi.org/10.2118/77861-MS Published: October 08 2002 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Moridis, G.J. "Numerical Simulation Studies of Thermally-Induced Gas Production From Hydrate Accumulations With No Free Gas Zones at the Mallik Site, Mackenzie Delta, Canada." Paper presented at the SPE Asia Pacific Oil and Gas Conference and Exhibition, Melbourne, Australia, October 2002. doi: https://doi.org/10.2118/77861-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Asia Pacific Oil and Gas Conference and Exhibition Search Advanced Search AbstractThe Mallik site represents an onshore permafrost-associated methane hydrate accumulation in the Mackenzie Delta, Northwest Territories, Canada. This study focuses on gas production at the Mallik site from hydrate deposits that are underlain by either a free water zone or by an impermeable boundary. The production analysis was conducted using a numerical simulator that can model the non-isothermal CH4 release, phase behavior and flow under conditions typical of CH4-hydrate deposits by solving the coupled equations of mass and heat balance. The simulator can describe any combination of the possible dissociation mechanisms (i.e., depressurization, thermal stimulation, salting-out effects and inhibitor effects). Accumulations with a CH4-hydrate saturation of at least 50% were studied. Dissociation was induced mainly by a combination of thermal stimulation and depressurization as hot fluids circulated between injection and production wells. The effects of salinity and of pressure changes at the wells were also accounted for. The production strategy resulted in a zero net water production. The simulation results indicated that the amounts of CH4 released from the dissociating hydrate deposits is sensitive to the hydrate saturation, the initial temperature, the specific enthalpy and the flow rate of the circulating fluids.IntroductionBackground. Gas hydrates are solid crystalline compounds in which gas molecules are encaged inside the lattices of ice crystals. Vast amounts of hydrocarbons are trapped in hydrate deposits 1. Such deposits exist under favorable thermodynamic conditions that occur 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. 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.1 The magnitude of this resource could make hydrate reservoirs a substantial future energy resource. Although the current energy economics cannot support gas production from hydrate accumulations, their potential clearly demands evaluation.The Mallik site represents an onshore permafrost-associated methane hydrate accumulation in the Mackenzie Delta, Northwest Territories, Canada. A significant body of literature2 on both the geology and the hydrate accumulations at the site became available following an 1150 m deep gas hydrate research well that was drilled in 1998. The objective of this study is to develop and evaluate strategies for gas production at the Mallik site from hydrate deposits that lack an underlying free gas zone. Thus, the hydrate intervals in this study are underlain by either a free water zone or by an impermeable boundary, and are particularly challenging because of high water production and/or adverse permeability conditions.The numerical model. The numerical studies of gas production in this paper were conducted using the TOUGH2 general-purpose simulator 3 for multi-component, multiphase fluid and heat flow and transport in the subsurface with the EOSHYDR2 module4,5. By solving the coupled equations of mass and heat balance, EOSHYDR2 models the behavior of methane-bearing binary hydrates that are formed or dissociate in porous media according to the general reaction equation: Keywords: injection well, hydrate accumulation, hydrate, dissociation, reservoir, gas release, flow assurance, permeability, gas production, vicinity Subjects: Flow Assurance, Improved and Enhanced Recovery, Hydrates This content is only available via PDF. 2002. 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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".