Abstract
In this study, we investigate a system of gas production from methane
hydrate layers involving hot water injection using dual horizontal wells.
Physical and numerical models simulating the gas production process from
methane hydrate layers within a hot water chamber are proposed.
Experiments with scaled two-dimensional physical models using an imitated
hydrate layer (NaHCO3 ice formation) were performed to investigate fluid flow
characteristics and production performance. The thermal simulator was used to
simulate experimental chamber growth and field production. Numerical
simulations for the processes were successfully performed with a two-component
(water and oil or methane hydrates), three-phase (water, methane hydrates and
methane gas) and three-dimensional model, matching the physical model. Results
of the history-matched numerical simulations were in good agreement with data
on production and chamber shapes obtained using the Intermediate3-Stone1
wettability model. Simulations of field production using dual horizontal wells
500 m in length were performed to evaluate cumulative gas production over 3
years of injection with 500 × 103 kg/day of hot water, which varied from 5 ×
106 to 9 × 106 std m3. The production process appears economical, in view of
the expected convective heat transfer from the chamber boundary and buoyancy
force on dissociated methane gas.
Introduction
Recent studies confirm that conserved methane hydrate deposits in
sedimentation layers at a depth of more than 200 to 300 m from the bottom of
the sea floor can be utilized as novel natural gas resources. In-situ hydrate
decomposition into water and gas is required to produce methane gas
economically from these layers, since methane hydrate is a type of non-mobile
solid energy resource. To trigger methane hydrate decomposition, decompression
or temperature increase out of the equilibrium zone is necessary, while heat
should be supplied for continuous dissociation. Accordingly, new gas production
systems that supply heat continuously into the methane hydrate layers have been
reported. The conventional methods of gas production to date include
depressurization, inhibitor injection and thermal recovery.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
22 October 2007
- Meeting paper published:
12 June 2007
- Revised manuscript received:
10 June 2009
- Manuscript approved:
8 September 2009
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