China's deepwater gas hydrate development strategies under the goal of carbon peak

Developing marine gas hydrate (hereinafter referred to as hydrate) in a large scale is one of China's major strategies for energy development. In order to determine China's strategies to deepwater hydrate under the goal of carbon peak, this paper classifies its development technologies into five types, i.e., laboratory simulation test technology, geological exploration technology, drilling and sampling technology, three-gas commingled production technology and environmental risk monitoring technology, according to the clustering analysis results of the papers and patents related to hydrate. In addition, hydrate development status and deepwater hydrate development direction are studied systematically. And the following research results are obtained. First, marine hydrate production technologies have the double attributes of great significance and great difficulty and they have strategic and revolutionary characteristics in the nation level and prospective and competitive features in the technical level. Second, the large-scale hydrate development in the sea areas of China still faces several theoretical and technologies difficulties. For example, the temporal and spatial evolution of reservoir heat, fluid, mechanics, space, structure and multiple fields are not understood clearly, the complex gas-liquid-sand-hydrate four-phase flow law from reservoir and wellbore to underwater Christmas tree, submarine pipeline and downstream process facility is not clarified, and the regeneration mechanism of hydrate is not recognized. Third, as for the development of deepwater shallow hydrate, high-accuracy detection technology and stereoscopic and comprehensive detection technology of geophysics, geology, logging and drilling are the main development directions in the future. Fourth, the hydrate resource evaluation method is on the way to be refined, the development mode and production test engineering of hydrate resource tend to the joint development of hydrate and oil & gas, and new commingled production technology and equipment will be the hot spot and frontier direction of following research. Furthermore, China's deepwater hydrate development path and the development theories and technology roadmap in 2020-2035 are put forward. In conclusion, the future development strategies of deepwater hydrate focus on exploring and breaking through the safe and efficient production technologies of surface, shallow and deep hydrate of different types and different occurrence forms. What's more, for different development modes of deepwater hydrate, it is in urgent need to establish a comprehensive monitoring and systematical evaluation mechanism from local to entire and from short term to long term, so as to ensure the stable production test and large-scale development of hydrate. © 2022, Natural Gas Industry Journal Agency. All right reserved.