Summary
The Research Consortium for Methane Hydrate Resources in Japan (MH21
Research Consortium) has been evaluating methane-hydrate (MH) reservoirs
located in the eastern Nankai trough from the viewpoints of geology,
geophysics, petrophysics, and reservoir/production engineering. As one of these
studies, we have been predicting gas/water production performances from these
MH reservoirs showing diverse characteristics. This paper presents the results
of our examinations on the applicability of a variety of MH
dissociation/production methods to these MH reservoirs and on the feasibility
of future development in terms of gas production and economics.
Eastern Nankai trough MH reservoirs, which are composed of alternating beds
of sand, silt, and clay in turbidite sediments, have various conditions of clay
distribution and of initial pressure, temperature, permeability, and MH
saturation. Some of these reservoirs contain MH of high saturation at a certain
interval (MH concentrated reservoir), while in the others, MH is deposited
sparsely (MH-nonconcentrated reservoir). Detailed numerical reservoir models
were constructed for both MH-concentrated and -nonconcentrated reservoirs,
consulting the well-log and seismic-interpretation results.
MH-dissociation/-production performances were then predicted through
numerical simulation, assuming the application of various MH-dissociation
methods (such as depressurization, wellbore heating, hot-water huff'n'puff, and
hot waterflooding. The simulation studies clarified the difference in the gas
production between MH-concentrated and -nonconcentrated reservoirs. These
studies also revealed that the permeability not only of sand layers but also of
clay layers has a significant effect on the gas productivity from
MH-concentrated reservoirs. Furthermore, it was suggested that the hot-water
injection was effective when it was applied as a secondary-recovery method
after depressurization. Simple economic analyses on the basis of these
simulation results exhibited the promise that some MH reservoirs in the Eastern
Nankai trough could be developed economically if the well spacing and
MH-dissociation/-production methods were designed appropriately.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
4 February 2008
- Meeting paper published:
5 May 2008
- Revised manuscript received:
8 October 2008
- Manuscript approved:
24 October 2008
- Published online:
1 June 2009
- Version of record:
1 June 2009
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