Prospect of marine natural gas hydrate stimulation theory and technology system

Abstract

The key to realize the commercial production of natural gas hydrate (NGH) is to increase theNGH productivity significantly in the scale of magnitude. Whether NGH production can be commercialized depends on two aspects. The first is whether the in-situ recoverable reserves are large enough to support the basic production period for commercial production. The second is whether the average productivity can reach the standard for commercial production. In this paper, we will analyze mainly about the potential stimulation technologies for NGH development, and discuss about the basic principles, the evaluation methods, and the technical bottlenecks for NGH production and stimulation. The results indicate that the main mechanisms for increasing theNGH productivity are in three respects, namely enlarging the drainage area, increasing the NGH dissociation efficiency, and improving the seepage conditions. With complex-structure wells and multiple-well patterns, combined with novel production methods and/or reservoir stimulation technologies, the NGH productivity can be increased greatly. Particularly, the complex-structure wells and well patterns are very important for increasing NGH productivity. With complex-structure wells and well patterns, combined with heat injection and/or reservoir stimulation, NGH productivity can be increased on a magnitude scale. Currently, in fundamental researches, there are some technical bottlenecks for the studies of NGH production, mainly in sample preparation, simulated reservoir monitoring, and mechanical coupling technologies. Therefore, it is suggested that the study focuses should be on the above technical bottlenecks during the basic research on how to increase the NGH productivity. It is concluded that the combined application of complex-structure wells (horizontal wells and multi-lateral wells), well-pattern production models (with multi-cluster/group well production), the novel production methods (mainly thermal stimulation, together with depressurization), and reservoir stimulation technologies (hydraulic fracturing) are the keys to increase NGH productivity in the scale of magnitude.