(457b) Comparison of Gas Production From Gas Hydrate Reservoirs Using Vertical and Horizontal Wells

Methane hydrates
may contain significant amounts of hydrocarbons both in the permafrost and in
oceans due to favorable settings of pressure and temperature. This simulation-based
work is aimed to estimate and compare natural gas production from
hydrate-bearing reservoirs on the Alaskan North Slope using horizontal and
vertical wells in hydrate bearing reservoirs. It has been established that high
amounts of gas can be obtained from hydrate reservoirs using depressurization
technique and vertical wells [1]. In this paper, numerical studies are conducted
on similar reservoirs using horizontal and vertical wells in the hydrate
bearing layers using CMG STARS. CMG STARS (Steam, Thermal, and Advanced
Processes Reservoir Simulator) is a three-phase multi-component thermal and
steam additive simulator, developed by the Computer Modeling Group Limited
(CMG). This paper also examines the feasibility of hydraulic fracturing in the
permafrost methane hydrate reservoirs.

The geologic
settings of the hydrate reservoirs are obtained from the USGS-NETL Methane
Hydrate Code Comparison project [2].  For comparison of performance of both the
wells, various values of porosity, intrinsic permeabilities, reservoir
temperature, hydrate saturation and free water saturation will be used in the
simulations and results will be compared. In the base reservoir model, a
hydrate layer is bound by two shale layers, above and below. The vertical well
simulation will be carried out using a cylindrical domain and the horizontal
well simulation will be carried out using a rectangular Cartesian domain.
Average pressure and temperature are 12°C and 9 MPa in the hydrate bearing
layer. The production will be adjusted to the volume of hydrate present in each
of the reservoirs. It is predicted that the horizontal well will produce gas
more instantaneously than the vertical well.

1.      
Sloan,
E.D., and C. Koh, Clathrate Hydrates of Nautral Gases. 3rd Edition, Boca
Raton, FL: Taylor and Francis, Inc., 2008

2.      
Wilder, J., et al. An
International Effort to Compare Gas Hydrate Reservoir Simulators. In Proceedings
of the 6th International Conferenceon Gas Hydrates. 2008. Vancouver,
British Columbia, Canada.