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Evaluation of gas production potential from gas hydrate deposits in National Petroleum Reserve Alaska using numerical simulations

Journal of Natural Gas Science and Engineering

By:
, , , , and
DOI:10.1016/j.jngse.2016.11.021

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Abstract

An evaluation of the gas production potential of Sunlight Peak gas hydrate accumulation in the eastern portion of the National Petroleum Reserve Alaska (NPRA) of Alaska North Slope (ANS) is conducted using numerical simulations, as part of the U.S. Geological Survey (USGS) gas hydrate Life Cycle Assessment program. A field scale reservoir model for Sunlight Peak is developed using Advanced Processes & Thermal Reservoir Simulator (STARS) that approximates the production design and response of this gas hydrate field. The reservoir characterization is based on available structural maps and the seismic-derived hydrate saturation map of the study region. A 3D reservoir model, with heterogeneous distribution of the reservoir properties (such as porosity, permeability and vertical hydrate saturation), is developed by correlating the data from the Mount Elbert well logs. Production simulations showed that the Sunlight Peak prospect has the potential of producing 1.53 × 109 ST m3 of gas in 30 years by depressurization with a peak production rate of around 19.4 × 104 ST m3/day through a single horizontal well. To determine the effect of uncertainty in reservoir properties on the gas production, an uncertainty analysis is carried out. It is observed that for the range of data considered, the overall cumulative production from the Sunlight Peak will always be within the range of ±4.6% error from the overall mean value of 1.43 × 109 ST m3. A sensitivity analysis study showed that the proximity of the reservoir from the base of permafrost and the base of hydrate stability zone (BHSZ) has significant effect on gas production rates. The gas production rates decrease with the increase in the depth of the permafrost and the depth of BHSZ. From the overall analysis of the results it is concluded that Sunlight Peak gas hydrate accumulation behaves differently than other Class III reservoirs (Class III reservoirs are composed of a single layer of hydrate with no underlying zone of mobile fluids) due to its smaller thickness and high angle of dip.

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Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Evaluation of gas production potential from gas hydrate deposits in National Petroleum Reserve Alaska using numerical simulations
Series title:
Journal of Natural Gas Science and Engineering
DOI:
10.1016/j.jngse.2016.11.021
Volume:
36
Issue:
A
Year Published:
2016
Language:
English
Publisher:
Elsevier
Contributing office(s):
Central Energy Resources Science Center
Description:
13 p.
First page:
760
Last page:
772
Country:
United States
State:
Alaska