Abstract
According to a recent seismic survey in the Gulf of Oman (GOO), hydrate bearing layers were detected through observation of significant bottom simulating reflector (BSR), flat spot and bright spot attributes. In addition, favorable geological conditions indicate possibility of gas hydrate formation in this region. Quantification of the hydrate resource using geological and geophysical techniques, while continuously improving is subject to very large uncertainties. Uncertainty associated with estimation of the thickness of the gas hydrate stability zone (GHSZ) is a source of error in prediction of the volume of hydrate-bound gas and gas production from gas hydrate reservoirs. In this paper we present a conceptual model of the thickness of the GHSZ varying over a wide range of input variables within the study area and use it along with sensitivity analysis to quantify the impact of these variables on the thickness of the GHSZ in the gas hydrate accumulations of the GOO. Using Milkov and Sassen's model, the thickness of the GHSZ is modeled on the basis of the GOO region properties for three kinds of gas hydrates with gas composition containing 100% methane, 95% methane and 90% methane. The results of sensitivity analysis show that geothermal gradient is the most effective parameter changing the thickness of the GHSZ, then seabed temperature and gas composition have the greatest impact, respectively. Furthermore, the results reveal that gas composition has indirect impact on the degree of influence of other parameters. Evaluating the source of the gas in the GOO, particularly at the beginning of the life of the reservoir which very limited information is available for engineering calculations is the usefulness of this sensitivity analysis.
