Method and system for recovering natural gas hydrate solid flow under the condition of underbalanced positive circulation

Abstract

The invention relates to a natural gas hydrate solid-state flow mining method and system under the condition of underbalanced positive circulation, which is used for solid-state flow mining of marine non-diagenetic weakly cemented natural gas hydrate layers. The equipment mainly consists of two parts: a ground equipment system and an underwater equipment system , the construction process includes the pre-construction process, the underbalanced solid-state flow drilling hydrate production process and the sediment backfilling process. Based on the basic technical idea of ​​solid-state flow exploitation, the invention adopts the underbalanced positive circulation method to exploit the submarine natural gas hydrate, and effectively solves the wellbore safety and production problems faced by conventional natural gas hydrate exploitation methods such as depressurization, heat injection, agent injection and replacement. Control, environmental risks and other issues, using the method of the present invention can realize the green, environmentally friendly, efficient, safe and economical exploitation of subsea weakly cemented non-diagenetic natural gas hydrate, provide more energy for the country, and then solve the dilemma of energy shortage faced by our country.

Description

technical field [0001] The invention relates to the technical field of unconventional oil and gas resource development, in particular to a method and system for recovering natural gas hydrate solid flow under the condition of underbalanced positive circulation. Background technique [0002] Natural gas hydrate is a non-stoichiometric cage crystal formed by water and natural gas under high pressure and low temperature. It is an unconventional energy source with high density and high calorific value. Natural gas hydrate (hereinafter referred to as hydrate) is a new type of The clean energy of the world has been receiving much attention, and the global ocean hydrate reserves are conservatively estimated to be 2.83×10 15 m 3 , about 100 times the amount of land resources, it is considered to be the most potential alternative energy source in the 21st century. The amount of prospective resources in my country explored by the Ministry of Land and Resources and other departments...

AI Technical Summary

Problems solved by technology

In the process of mining hydrates by means of depressurization, heat injection, agent injection, and replacement, the sand particles produced by the decomposition of hydrates are carried by natural gas into the wellbore, which in turn causes wellbore safety problems such as sand production at the bottom of the well.

After the reservoir hydrate decomposes, the original framework structure of the reservoir collapses, and the stress field of the formation changes, resulting in production control risks such as wellbore and reservoir collapse, and mining equipment being buried.

Hydrate decomposes to produce a large amount of natural gas, which penetrates the formation along the pore channels of the formation, escapes from the sea surface and enters the atmosphere, causing various environmental risks

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