Improved Prediction Method for Gas Hydrate Saturation in Sea Areas

Abstract

Ninety-eight % of the world’s natural gas hydrate (commonly known as hydrate) are distributed in the stability zone of the sea areas. There are also rich hydrates in the stability zone of the Shenhu Sea Area in China. Drilling in the Shenhu Sea Area of China reveals that a lot of hydrate exist in suspension mode. Now the Wood method is for predicting hydrate in suspension mode, but the practical application in the Shenhu Sea Area shows that this method leads to large errors in predicting hydrate saturation. In order to address the problem of low accuracy of the Wood method in predicting hydrate saturation in suspension mode, this paper has first pointed out that the low accuracy of the Wood method is primarily caused by the systematic analytic error of stratigraphic parameters, which is derived from insufficient understanding of sediment composition and porosity in sea area by existing analytic technology. The paper puts forward the Wood-SE method alternatively. The practical application in the Shenhu Sea Area shows that the absolute error of this method mainly falls within the range of -10%, 10%. Most of the absolute error of the Wood method is above 20%. The error of main hydrate occurrence section could even reach 60%.