METHOD AND SYSTEM FOR MINING NATURAL GAS HYDRATE SOLID-STATE FLOW UNDER UNDER-BALANCED FORWARD CIRCULATION CONDITION

摘要

A method and system for mining a natural gas hydrate solid-state flow under an under-balanced forward circulation condition, which is used for performing solid-state flow mining on a weakly cemented non-diagenetic natural gas hydrate layer in the ocean. The present system is mainly composed of a ground equipment system and an underwater equipment system. The present mining method comprises a preliminary construction process, an under-balanced solid-state flow drilling hydrate construction process, and a sediment backfilling process. The method for mining a natural gas hydrate solid-state flow under an under-balanced forward circulation condition is based on the basic technical idea of solid-state flow mining, and an under-balanced forward circulation method is used to mine natural gas hydrates in the seabed, which effectively solves problems such as wellbore safety, production control, environmental risks and the like that face against conventional mining methods for reducing pressure, injecting heat, injecting an agent, and replacing natural gas hydrates. The use of the method for mining a natural gas hydrate solid-state flow under an under-balanced forward circulation condition may achieve the environmentally friendly, efficient, safe and economic mining of weakly cemented non-diagenetic natural gas hydrates in the seabed.